Confined Space Safety Publications


Grain Bins

Topic Titles Organization Pub Date
Beware of Flowing Grain Dangers Purdue Extension 2010
Grain Bin Hazards and Safety Considerations Alabama Cooperative Extension 2008
Grain Storage Safety University of Maine Extension 2002
Hazards of Flowing Grain Pennsylvania State University 2014
Managing Moldy Grain Purdue Extension 2010
Safe Operating Procedure – Grain Bin Safety University of Nebraska 2009
Safe Operating Procedure – Harvest Safety University of Nebraska 2009

 

Manure Storage

Topic Titles Organization Pub Date
Confined Space Manure Gas Monitoring Pennsylvania State University 2011
Confined Space Manure Storage Emergencies Pennsylvania State University 2011
Confined Space Manure Storage Hazards Pennsylvania State University 2011
Confined Space Manure Storage Ventilation Systems Pennsylvania State University 2011
Harvesting Health Series: Manure Gases National Farm Medicine Center 2009
Open Air Manure Storage Safety Tips Pennsylvania State University 2012

 

Silos

Topic Titles Organization Pub Date
Harvesting Health Series: Silo Gas National Farm Medicine Center 2009
Safety and Health: What You Need to Know about Silo Gas – A Deadly Killer Iowa State University Extension and Outreach 2008
Silo Gas Safety Government of Alberta – Agriculture and Rural Development 2004
Upright Silo Safety University of Maine Extension 2002

 

Ventilation Systems for Confined Space Manure Storage

Pig Barn with Slotted Floor

(Source: Agricultural Safety and Health, Pennsylvania State University)

 

Use the following format to cite this article:

Ventilation systems for confined space manure storage. (2013). Farm and Ranch eXtension in Safety and Health (FReSH) Community of Practice. Retrieved from http://www.extension.org/pages/67438/ventilation-systems-for-confined-space-manure-storage.

 

Ventilation is crucial in reducing risk exposure when entering a confined space manure storage. A manure storage is considered a confined space based on the criteria established by the Occupational Safety and Health Administration (OSHA). OSHA defines a confined space as 1) being a large enough space and configured in such a way that an employee can bodily enter and perform assigned work; 2) having limited or restricted means for entry or exit; and 3) not designed for continuous employee occupancy.

The following hazards exist in a confined space manure storage:

  1. Lack of oxygen,
  2. Toxic and flammable gases, and
  3. Potential exposure to drowning.

Ventilation Recommendations

The four main types of gases that can be in a manure storage area include hydrogen sulfide, ammonia, methane, and carbon dioxide. Ventilation of the area is recommended to decrease the level of these gases and to replenish the oxygen level in the manure storage.

Ventilation recommendations are based on the ANSI/ASABE S607 standard that was approved in October 2010 by the American Society of Agricultural and Biological Engineers. This standard was developed to reduce risk from asphyxiation, poisoning, and explosions prior to entering a confined space manure storage by specifying the positive pressure, forced ventilation requirements for the manure storage.

The type of flooring that is selected is based on the construction details of the facility and the type of animals being housed. Flooring type affects the type and design of ventilation systems to maximize air movement. The three main types of manure storage flooring and covers are solid, totally slotted, and partially slotted. A solid cover storage can be located beneath or outside the animal housing facility and may have a square, rectangular, or circular footprint. Rectangular and square storage footprints are typically used for partially and totally slotted floors that are located directly below the animal’s living area.

When a manure storage is being ventilated at an air exchange rate of 1.5 AC/m, the ANSI/ASABE S607 standard provides calculated times required to reduce hazardous gases to an acceptable level and to replenish the oxygen level from 0% to 20% within each type of manure storage tank. The standard also provides transformation equations or adjustment factors for alternative ventilation strategies, changes in AC rate, initial gas concentration levels lower than maximum documented levels, and differing fresh air intake locations. Click here for detailed information about calculated ventilation times, adjustments to calculated ventilation times, and information concerning the evacuation of animals from slotted-cover manure pits prior to ventilation.

Summary

The ANSI/ASABE S607 standard was designed to reduce the risk of entry into manure storages. In addition to recommended ventilation procedures, agricultural producers and workers should follow these recommendations:

  • Properly post warning signs near the entrance to confined space manure storage facilities.
  • Maintain ventilation instructions near the confined space manure storage for easy access in an emergency situation.
  • Never work by yourself when entering a storage. A second person who does not enter the confined space is needed.
  • Always monitor the gas levels in the storage before and during the entry event.
  • Ventilate the storage for the rate and time outlined in ANSI/ASABE S607 before and during the entry event.
  • Always use a safety harness and emergency retrieval system when entering a confined space manure storage.

Resources

To better understand strategies for reducing entry risks, view the following videos from the Pennsylvania State University:

Reducing Risk When Entering a Confined Space Manure Storage

Manure Storage Ventilation Demonstration: Slotted Floor Storage

Manure Storage Ventilation Demonstration: Solid Covered Storage

 

Click HERE to visit the Manure Pit Safety page by the Pennsylvania State University for additional information including fact sheets, manure pit standards and regulations, and the manure pit safety demonstration trailer.

Click on an article title below to be directed to an article from the Farm & Ranch eXtension in Safety and Health (FReSH) Community of Practice:

Confined Spaces Manure Storage Emergencies

Confined Spaces Manure Storage Hazards

Confined Spaces Manure Gas Monitoring

 

 

Use the following format to cite this article:

Ventilation systems for confined space manure storage. (2013). Farm and Ranch eXtension in Safety and Health (FReSH) Community of Practice. Retrieved from http://www.extension.org/pages/67438/ventilation-systems-for-confined-space-manure-storage.

 

 

Sources

Manbeck, H., Murphy, D., & Steel, J. (2011) Confined space manure storage ventilation systems. Pennsylvania State University. Retrieved from https://extension.psu.edu/confined-space-manure-storage-ventilation-systems.

 

Reviewed and Summarized by:
Linda M. Fetzer, Pennsylvania State University – lmf8@psu.edu
Dennis J. Murphy, Pennsylvania State University (Has since retired)
J. Samuel Steel, Pennsylvania State University (Has since retired)
Aaron M. Yoder, University of Nebraska Medical Center – aaron.yoder@unmc.edu
 

Confined Space Safety Video Resources


Grain Bins

Topic Titles Organization Resource Types

Farm S.O.S. (Strategies on Safety) Curriculum Videos: Grain Bin Awareness (2014)

1:26 minutes

Ohio State University Free – Online video via YouTube

Farm S.O.S. (Strategies on Safety) Curriculum Videos: Lock Out/Tag Out (2014)

1:10 minutes

Ohio State University Free – Online video via YouTube

Following Proper Grain Bin Entry Procedures Saves Lives (2013)

3:45 minutes

Grain Handling Safety Coalition Free – Online video via YouTube

Grain Rescue (2009)

2:42 minutes

The Ohio State University Free – Online video via YouTube

Grain Bin Safety: Protecting Yourself and Your Family

13:40 minutes

National Corn Growers Association and National Grain and Feed Foundation Free – Online video

Grain Bin Entrapment | Seconds to Tragedy | Grain Handling Safety Coalition

14:30 minutes

Grain Handling Safety Coalition Free – Online video via YouTube

Manure Storages

Topic Titles Organization Resource Types

Confined Space Safety on the Farm (2011)

3:43 minutes

The Ohio State University Free – Online video via YouTube

Farm S.O.S. (Strategies on Safety) Curriculum Videos: Manure Pit Confined Space (2014)

1:14 minutes

The Ohio State University Free – Online video via YouTube

Manure Pit Safety Introduction (2011)

2:46 minutes

Pennsylvania State University

Free – Online Video via YouTube

Manure Pit Safety: An Interview with Dennis Murphy (2012)

3:53 minutes

Progressive Dairyman

Free – Online Video via YouTube

Slotted Floor Manure Storage Ventilation and Safety (2011)

27:02 minutes

Pennsylvania State University

Free – Online Video via YouTube

Solid Cover Manure Storage Ventilation and Safety (2011)

24:07 minutes

Pennsylvania State University

Free – Online Video via YouTube

 

Dangers of Silo Gases


Use the following format to cite this article:

Dangers of silo gases. (2012) Farm and Ranch eXtension in Safety and Health (FReSH) Community of Practice. Retrieved from http://articles.extension.org/pages/64390/dangers-of-silo-gases.

 

After harvested forages are placed in a silo, they often produce gases during the early stages of the fermentation process. Silo gases are difficult to detect because they are almost invisible, but signs of such gases may include:

  • the formation of a faint yellow or red haze that appears from the top of a conventional silo to the bottom of the ladder chute, 
  • staining on the silo and silage, and
  • a bleach-like odor that may be present even at the base of the silo and in the milking parlor.

If you detect silo gases, leave the area immediately. Physical reactions to silo gases may not be noticeable immediately after your exposure, but damage to your lungs may have already occurred. (Click here to learn more about respiratory illnesses related to farming practices in production agriculture.)

The most common silo gases are carbon dioxide (CO2and nitrogen dioxide (NO2). Types and concentrations of silo gas vary depending on whether the silo is a conventional silo or oxygen-limiting silo and how much time has passed since the silage was placed in the silo.

Conventional Silos

Conventional Silo

Conventional Silo

(Source: Pennsylvania State University. Agricultural Safety and Health)

Conventional silos are often constructed of concrete staves held together with steel hoops, but some are made of reinforced concrete, steel, galvanized tile, or brick.

The most abundant type of gas in a conventional silo is nitrogen dioxide, which has a bleach-like odor and produces low-lying yellow, red, or dark brown fumes. Because it is heavier than air, nitrogen dioxide settles on top of the silage or flows down the chute and collects in adjoining feed rooms or other low-lying areas in the barn near the base of the silo.

Nitrogen dioxide begins to form within hours after the forages are ensiled, with the amount of gas peaking about three days after harvest. From that point, the amount of gas begins to decrease rapidly.

Nitrogen dioxide is harmful because it causes severe irritation to the nose and throat, which can lead to lung inflammation. After low-level exposure to nitrogen dioxide, a person may experience very little immediate pain or discomfort but may later suffer from fluid collection in the lungs that may be fatal. Prolonged or recurring pneumonia-like symptoms can occur two to six weeks after initial exposure. Any person who has been exposed to any level of nitrogen dioxide, for even a short period of time, should seek immediate medical attention.

Oxygen-Limiting Silos

Silos

(Source: Pennsylvania State University. Agricultural Safety and Health)

An oxygen-limiting silo is constructed of dark blue or green enamel-coated steel, poured reinforced concrete, or concrete staves. Oxygen-limiting silos are designed so that entering the silo is typically unnecessary. 

In this type of silo, the fermentation process produces both nitrogen dioxide and carbon dioxide. The conditions in an oxygen-limiting silo promote greater production of carbon dioxide, which helps maintain high-quality silage.

Carbon dioxide is an odorless and colorless gas that displaces the life-sustaining oxygen in a silo. When levels of carbon dioxide are high, a person may have little warning before being overcome by this gas. 

Modified Oxygen-Limiting Silo

A modified oxygen-limiting silo is an oxygen-limiting silo that has been modified with a different type of unloading system. The unloading system is located on the top of the silage and unloads through a hollow center chute. An oxygen-limiting silo can also be modified with the addition of a conventional top-unloading system, unloading doors, and a chute along the outside of the silo tower. Silos with a top-unloading system typically have a domed roof to provide space for the tripod that suspends the unloader.

As in an unmodified oxygen-limiting silo, the respiration and fermentation process converts the oxygen in the silo into carbon dioxide. The design of a modified oxygen-limiting silo typically makes entry unnecessary.  

Decreasing the Risk of Exposure to Silo Gases in Conventional Silos

  • Ventilation: When you use a conventional silo on your farm or ranch, ventilation is the best defense against nitrogen dioxide buildup in areas of your barn and the best away to lower the risk to your livestock.

    • Provide adequate ventilation in and around your silo during the first 72 hours of silage fermentation and for at least two to three weeks after filling the silo.
    • Keep the door between the silo room and the barn closed.
    • Consider using barn exhaust fans to blow air into the silo or feed room to decrease quantities of silo gases that may have flowed down the chute.
  • Timing: Avoid the silo during critical periods when silo gases are forming. Gas concentrations are highest between 12 and 72 hours after filling.

    • If at all possible, do not enter the silo for two to three weeks after filling because of the high level of silo gases. If you must enter the silo during that time to level silage or set up an unloader, enter immediately after the last load is in and before the fermentation process begins—a period that may be only a few hours. (Follow the same precautions below if entry is required within four to six weeks after filling.)
      • Prior to entry, run the silo blower for 15 to 45 minutes and keep it running while you are in the silo.
      • Wear a self-contained breathing apparatus (SCBA) and a harness attached to a lifeline and anchor point.
      • Always maintain visual contact with a second person outside the silo.
      • If the level of the silage is low, a silo blower will not provide enough ventilation to dilute the silo gases. Do not enter the silo without wearing an SCBA.
    • Prior to entering any silo at any time, make sure that the power supply for all unloading mechanisms is locked out.
  • Personnel: Never enter a silo unless there is another person present outside the silo who can quickly get help if necessary. This person should maintain visual contact with you at all times because if you are overcome by silo gas, you may not be able to call out for assistance.
  • Personal Protective Equipment (PPE): If, in an emergency, it is necessary to enter a silo containing silage, the individual entering the silo must wear an SCBA. Click here to learn more about respiratory protection equipment. 
  • Signage: Post appropriate signage warning people of the potential for silo gases. By posting “Danger—Deadly Silo Gas” signs around the base of the silo, you are warning visitors, family members, and workers to stay away from the area.

Additional Recommendations

  • Keep children away from the silo and adjoining areas during filling and for at least two weeks after.
  • When uncovering the filler opening, stay positioned on the ground and use a rope to pull the cover off the filler opening. Remove the cover several days before you start using the silage.
  • If you begin to cough or experience throat irritation while working near a silo, move to a source of fresh air immediately.
 

Use the following format to cite this article:

Dangers of silo gases. (2012) Farm and Ranch eXtension in Safety and Health (FReSH) Community of Practice. Retrieved from http://articles.extension.org/pages/64390/dangers-of-silo-gases.

 

Sources

 

Atia, A. (2004) Silo gas (NO2) safety. Agri-Facts. Retrieved from http://www1.agric.gov.ab.ca/$department/deptdocs.nsf/all/agdex9036/$file/726-1.pdf?OpenElement.

Cyr, D. and Johnson, S. (2002) Upright silo safety. University of Maine Cooperative Extension. Retrieved from http://umaine.edu/publications/2305e/.

McFadden, M. (2011) Beware of silo gases. Michigan State University Extension. Retrieved from http://news.msue.msu.edu/news/article/beware_of_silo_gas.

Murphy, D. (2013) Silo gases—the hidden danger. Pennsylvania State University Cooperative Extension. Retrieved from https://extension.psu.edu/silo-gases-the-hidden-danger. .

Murphy, D. and Arble, W. (2000) Extinguishing fires in silos and hay mows. New York: Natural Resource, Agriculture, and Engineering Service.

 

Reviewed and summarized by
Linda M. Fetzer, Pennsylvania State University – lmf8@psu.edu
Dave Hill, Pennsylvania State University (Has since retired)
Dennis J. Murphy, Pennsylvania State University (Has since retired)
J. Samuel Steel, Pennsylvania State University (Has since retired)
Aaron M. Yoder, University of Nebraska Medical Center – aaron.yoder@unmc.edu
 

 

 

Monitoring Manure Gases


Use the following format to cite this article:

Monitoring Manure Gases. (2012) Farm and Ranch eXtension in Safety and Health (FReSH) Community of Practice. Retrieved from http://www.extension.org/pages/64075/monitoring-manure-gases.

 

The four main toxic gases found in manure storage areas are ammonia, carbon dioxide, hydrogen sulfide, and methane. Due to the toxicity of these gases, you must check and monitor gas levels in confined space manure storage areas prior to entering them and while in them.

Additionally, you must monitor oxygen levels to ensure that spaces contain adequate supplies of air.

Portable electronic gas monitors are available to test the levels of both toxic gases and oxygen in a confined space, but it is important to ensure that the monitor you choose will test the level of all the relevant gases.

Portable Electronic Gas Monitors

Handheld Gas Monitor

Handheld Gas Monitor

(Source: Pennsylvania State University. Agricultural Safety and Health)

Depending on your budget, you can borrow, lease, or purchase electronic gas detection equipment. There are two types of gas detection devices for monitoring manure storage areas:

  • Installed monitors: Installed, or fixed, gas detection systems are typically more costly and not practical for confined space manure storage areas because such environments corrode a monitor’s electrical components.
  • Portable monitors: These devices are recommended over installed monitors because they can be stored in a protected space when not in use. They include portable electronic single-gas or multigas monitors. 

Methane is explosive at certain concentrations; hydrogen sulfide is lethal at high concentrations; low levels of oxygen can be deadly. A single-gas monitor measures only one of these components. A multigas monitor should have the capability to detect dangerous levels of hydrogen sulfide and methane and dangerously low concentrations of oxygen (0% to 30% by volume). Therefore, a monitor with multigas capabilities provides more information prior to a person entering a potentially dangerous space. 

Gas Monitors with Pumps

Some portable electronic gas monitors are equipped with pumps that allow them to test gas levels without being carried into manure storage areas. During the sampling process, the pump’s plastic tube is lowered into the storage area to within a few inches of the manure surface. The tube should never touch the manure. Measurements should be taken at multiple locations above the manure surface.

Gas levels should be tested at two locations in the confined space for different gases:

  • At the manure surface for the heavier gases carbon dioxide and hydrogen sulfide.
  • In the air approximately 12 inches below the top of the storage unit for the lighter gases ammonia and methane.

Measurements should be done prior to entry and continuously while any person is in the confined space. 

Gas Detection Badges

Another portable device is a gas detection badge, which is worn by a worker to track his or her exposure to contaminants. However, gas detection badges are not recommended for use in confined space manure storage areas because they may give inaccurate readings and they do not provide timely results. In addition, a gas detection badge may not provide readings for oxygen levels.

Gas Detector Tubes

A gas detector tube is a single-use gas detection device that provides a reading for one specific gas. Gas detector tubes do not monitor oxygen levels and provide only an approximate reading for the air being sampled.  

Maintenance of Portable Equipment

Regular maintenance, testing, and calibration of gas monitoring equipment enable it to work properly and extend its life. Maintenance and calibration are generally simple to execute. Follow the manufacturer’s recommendations when calibrating your monitor and use the certified standard gas concentrations. When possible, calibrate your monitor under environmental conditions that are similar to those where you will be using the monitor. As the device ages, calibration often becomes more difficult to complete, and you may need to replace the device or gas sensors. 

Before using a portable electronic gas monitor, remember to fully charge the device or to have fresh batteries available.

Store the device in a clean, dry, dust-free storage container. 

 

Use the following format to cite this article:

 

Monitoring Manure Gases. (2012) Farm and Ranch eXtension in Safety and Health (FReSH) Community of Practice. Retrieved from http://www.extension.org/pages/64075/monitoring-manure-gases.

 

Citations:

Ogejo, J. (2009) Poultry and livestock manure storage: Management and safety. Virginia Cooperative Extension. Retrieved from https://pubs.ext.vt.edu/442/442-308/442-308.html.

Steel, J., Murphy, D., and Manbeck, H. (2011) Confined space manure gas monitoring. Penn State Extension. Retrieved from https://extension.psu.edu/confined-space-manure-gas-monitoring.

 

Reviewed and Summarized by:
Linda M. Fetzer, Pennsylvania State University – lmf8@psu.edu
Davis E. Hill, Pennsylvania State University (Has since retired)
Dennis J. Murphy, Pennsylvania State University (Has since retired)
J. Samuel Steel, Pennsylvania State University (Has since retired)
Aaron M. Yoder, University of Nebraska Medical Center – aaron.yoder@unmc.edu
 

Confined Spaces: Emergencies and Rescue

Use the following format to cite this article:

Confined space: Emergencies and rescue. (2012) Farm and Ranch eXtension in Safety and Health (FReSH) Community of Practice. Retrieved from http://www.extension.org/pages/63150/confined-spaces:-emergencies-and-re….

 

Entering a confined-space manure storage area can be deadly. Farm and ranch managers, family members, and employees must have a complete understanding of what to do in the event of a confined-space emergency and ways to avoid such an incident.

If you find a victim unresponsive in a manure storage area, immediately call 911. Inform the operator that the incident involves a person in a confined-space manure storage area so that the appropriate emergency response personnel can be dispatched to the scene. Emergency responders trained in confined-space rescue will be equipped with the necessary rescue apparatus and gas detection equipment. Do not enter the manure storage area under any circumstances. 

While waiting for an emergency response team, ventilate the area by blowing fresh air into the space, moving the toxic air away from the victim. Keep a ventilation fan readily available specifically for such emergencies. When using a fan, be aware of the following recommendations:

  • Do not use typical barn or home fans to ventilate manure-storage areas because they may emit sparks from static electricity or an electrical short. If flammable methane gas has collected in the storage area, a spark could cause a fire.
  • Never attempt to get fresh air closer to the victim by lowering a fan into the confined space.
  • Make sure that the ventilation fan does not blow the manure gases back toward you, affecting your breathable air.

Preventing Confined-Space Manure Storage Emergencies

Take the following precautions on your farm or ranch to reduce the risk of a confined-space manure storage emergency:

  • Warning Signs: Post warning signs (example is shown below) about the risks of confined spaces and gas hazards at the openings to manure storage areas. Include warnings against walking or driving on crusted manure surfaces.

    Confined Space Sign

(Source: Pennsylvania State University. Agricultural Safety and Health)

  • Limited Access: Limit access to manure storage areas to authorized personnel. Take these specific steps to keep people away from manure storage areas:

    • Equip exterior ladders with locking mechanisms.
    • Remove temporary-access ladders from areas surrounding aboveground tanks.
    • When manure storage areas are open, place barricades at the openings of storage areas.
    • Install and maintain fencing around uncovered ground-level storage areas such as manure ponds or lagoons.
  • Education: Educate employees, family members, and visitors about the hazards associated with manure storage in confined spaces.
  • Entry Plan: Prepare and document an entry plan for entering confined spaces where manure is stored. Review the entry plan annually with all employees and family members. The entry plan should include specific physical details about the confined space, descriptions of potential hazards, reasons for entry, procedures for entry, and procedures to follow during emergencies. 
  • Two-Person Minimum: Require that two people be present for any confined-space entry and that both individuals be trained in entry and rescue techniques. The person outside the manure storage area should maintain verbal and visual contact with the person inside the confined space at all times. The person outside the storage area should be available to summon help and to implement the rescue and retrieval system if necessary. This person should not enter the manure storage area, even in the event of an emergency.
  • Gas Detection: Use gas detection equipment to monitor oxygen levels and levels of explosive and toxic gases in the confined space.    

Gas Monitor

(Source: Pennsylvania State University. Agricultural Safety and Health)

  • Ventilation: Prior to entry, ventilate the confined-space manure storage area for a minimum of 15 minutes and continue ventilation during entry and occupancy. A positive-pressure ventilation system is recommended because of the reduced risk of fire or explosion.
  • Body Harness: Require that the person entering the manure storage area carry a portable gas monitor and wear an adjustable body harness with a lifeline attached to a rescue and retrieval system. A typical rescue and retrieval system uses a tripod device equipped with a winch to limit a person’s fall and retrieve a person who has been incapacitated. 
  • Power-Source Lockout: To reduce the risk of stray electricity, prior to entry, lock out all power sources in the confined-space manure storage area other than the positive-pressure ventilation system.

Additional Safety Recommendations

  • Remember that youth under the age of 16 are prohibited from working in confined spaces.
  • Provide training about the hazards associated with confined-space manure storage to every person working on, living on, or visiting the farm or ranch.
  • Ventilate manure storage areas appropriately to increase oxygen and decrease explosive and toxic manure gases.
  • Remove personnel and animals from the confinement building during manure storage agitation or pumping. If you are unable to remove the animals, maximize ventilation and begin agitating very slowly while monitoring the animals for abnormal behavior.
  • Prohibit smoking in and around manure storage areas.
  • Operate manure agitators below the surface of liquid manure to reduce the release of manure gases. 
  • Leave 1 to 2 cu. ft. of space above the manure to contain released gases. If you are unable to leave the recommended space, lower the manure level prior to agitation.

 

Use the following format to cite this article:

Confined space: Emergencies and rescue. (2012) Farm and Ranch eXtension in Safety and Health (FReSH) Community of Practice. Retrieved from http://www.extension.org/pages/63150/confined-spaces:-emergencies-and-re….

 

Sources

 

Hallman, E. & Aldrich, B. (2007) Hydrogen sulfide in manure handling systems: Health and safety issues. Cornell University Manure Management Program. Retrieved from http://www.manuremanagement.cornell.edu/Pages/General_Docs/Fact_Sheets/H2S_Safety_factsheet_2007.pdf.

Hill, D., Murphy, D., Steel, J., & Manbeck, H. (2011) Confined space manure storage emergencies. Penn State Extension. Retrieved from http://www.agsafety.psu.edu/factsheets/E54emergencies.pdf.

Ogejo, J. (2009) Poultry and livestock manure storage: Management and safety. Virginia Cooperative Extension. Retrieved from https://pubs.ext.vt.edu/442/442-308/442-308.html.

 

Reviewed and Summarized by:
Linda M. Fetzer, Pennsylvania State University – lmf8@psu.edu
LaMar Grafft, East Carolina University – grafftl@ecu.edu
Davis E. Hill, Pennsylvania State University – (has since retired)
Dennis J. Murphy, Pennsylvania State University – (has since retired)
Aaron M. Yoder, University of Nebraska Medical Center – aaron.yoder@unmc.edu
 

Entrapment Risk due to Flowing Grain


Use the following format to cite this article:

Entrapment risk due to flowing grain. (2012) Farm and Ranch eXtension in Safety and Health (FReSH) Community of Practice. Retrieved from http://www.extension.org/pages/63151/entrapment-risk-due-to-flowing-grain.

Farmers and ranchers use bins to dry and store grain and to feed their livestock. For the most part, augers are used to transfer the grain to and from bins. Some machinery and augers now used in production agriculture have increased in size and power, resulting in less time for farmers and ranchers to react in dangerous situations. It is therefore important to understand fully the hazards and risks associated with flowing grain and to follow safety guidelines to avoid a potentially fatal injury incident. There are four main situations that pose entrapment risks when you work with stored grain: flowing grain, grain bridge collapse, grain wall avalanche, and use of a grain vacuum. Each of these situations and its entrapment risks are described below.

Flowing Grain

Grain Bin with Flowing Corn

(Source: Pennsylvania State University. Agricultural Safety and Health)

An auger is used to move grain from the bottom center to the outer edge of a grain bin, and from there into a vehicle or alternative storage area. As the grain flows, it forms a funnel, with the wide mouth of the funnel at the top and a smaller opening at the bottom, as shown in the diagram above. If you are in the bin when the grain is being unloaded, you can quickly become engulfed in grain. Depending on the size of the auger, you can be trapped in grain up to your waist within 10 seconds and completely submerged within 25 seconds. Once you are submerged in grain, it can take over 1,000 lb. of force to free your body.

Grain Bridge Collapse

Farmer on Moldy Corn Bridge

(Source: Pennsylvania State University. Agricultural Safety and Health)

A grain bridge forms when grain in poor condition exists throughout a bin. Cavities or pockets of loose grain can form under the crusted level when the auger begins to unload grain from the bin. Grain bridges are not stable, and if you are standing on top of a grain bridge when it collapses, you can quickly become entrapped in the grain. Once you fall through the grain bridge and are trapped, it may be difficult to locate you because the grain will flow rapidly into the area around you.

The proper way to break up or remove a grain bridge is to use a long pole inserted through an access hole from outside the grain bin.

Grain Wall Avalanche

Farmer in Bin with Corn

(Source: Pennsylvania State University. Agricultural Safety and Health)

Moldy or frozen grain can cling to the side of a grain bin, as shown in the diagram above. A grain avalanche can occur when you are breaking up crusted grain from within a bin and the grain wall is higher than you. The grain wall can collapse, creating an avalanche that can quickly engulf you, causing injury or death.

If you must enter a bin, use a body harness and a safety line that is securely tied off. Work above the vertical grain wall, staying above its highest point.

Use of a Grain Vacuum

Grain vacuums are being used with higher frequency as a means of moving grain rapidly from older bins with smaller unloading augers, bins in remote locations without augers, and bins that have mechanical problems. Powered by a tractor power take-off, electricity, or an external motor, these vacuums have the capacity to move several thousand bushels of grain an hour. Typically, an operator uses the vacuum inside the bin, moving the nozzle in a sweeping motion. During the last few years, several operators have been killed when using the equipment in this manner. If the operator drops or releases the nozzle, it can quickly become buried in grain. As a result, the operator may try to lift the nozzle while the vacuum is running. This can cause the grain to be sucked out from under the operator, burying him or her in seconds.

Below are two videos that demonstrate the use of a grain vacuum. To view a grain vacuum in use within a bin, click on the video below.

 

To see a grain vacuum transferring grain into a truck, click on the video below.

Suffocation in Grain Bins

Flowing grain is similar to quicksand and can quickly engulf you, resulting in suffocation. When even a small amount of grain has space to move, it quickly fills in that new area. When you are trapped by grain and exhale to breathe, the grain flows into the space created by the movement of your chest, placing pressure on your chest and reducing the space that your lungs have to expand during your next inhalation. Each time you exhale a breath, the space around your chest decreases, eventually causing you to suffocate as you take smaller and smaller breaths (or shallower and shallower). When you are trapped in flowing grain, you can also suffocate from taking grain particles into your lungs, stomach, and throat.  

Entrapment in Grain Transport Vehicles

Entrapment incidents can occur in grain transport vehicles that are used to move grain from one location to another. The most common types of grain transport vehicles are gravity wagons and bulk material semitrailers. Entrapment in these vehicles is similar to entrapment in a grain bin: a quicksand effect can occur during the loading or unloading process. 

Safety Recommendations

  • Lock all access doors to grain storage structures.
  • Secure grain bin ladders and doors to prevent unauthorized entry, especially by children.
  • Never allow children to play or ride in grain wagons. Most grain entrapment incidents in on-farm transport vehicles involve children.
  • Apply entrapment warning decals to all grain bins, wagons, and grain storage areas, as well as commercial transport vehicles.
  • Never work alone! When working with others during grain unloading, know where each person is located and what he or she is doing.
  • Warn workers, family members, and visitors about the dangers of flowing grain and the risk of entrapment.
  • Establish a nonverbal communication system with others when working around flowing grain because of the excessive equipment noise levels.
  • When possible, use inspection holes and grain bin level markers rather than physically entering a grain bin.
  • Before entering the grain bin, lock out and tag out all power controls to unloading augers and conveyors.
  • If you must enter the grain bin, wear a body harness with a lifeline secured to the outside of the bin, and have at least one other person observing your work activity in the bin.
  • When cleaning a grain bin, always work from top to bottom.

 

 

Use the following format to cite this article:

Entrapment risk due to flowing grain. (2012) Farm and Ranch eXtension in Safety and Health (FReSH) Community of Practice. Retrieved from http://www.extension.org/pages/63151/entrapment-risk-due-to-flowing-grain.

 

 

Sources

LaPrade, J. (2008) Grain bin hazards and safety considerations. Alabama Cooperative Extension System. Retrieved from http://www.aces.edu/pubs/docs/A/ANR-1332/ANR-1332.pdf.

Schwab, C., Hanna, M. & Miller, L. (2004) Handle your grain harvest with care. Iowa State University Extension and Outreach. Retrieved from https://store.extension.iastate.edu/ItemDetail.aspx?ProductID=4614.

Training module: Grain bin entrapment. (2002). Ohio State University Extension Agricultural Tailgate Safety Training. Retrieved from http://nasdonline.org/172/d001693/grain-bin-entrapment.html.

Yoder, A., Murphy, D. & Hilton, J. (2003). Hazards of flowing grain. Pennsylvania State University College of Agricultural Sciences Cooperative Extension. Retrieved from https://extension.psu.edu/hazards-of-flowing-grain.

 

 
Reviewers, Contributors, and Summarized by:
Linda M. Fetzer, Pennsylvania State University – lmf8@psu.edu
LaMar Grafft, East Carolina University grafftl@ecu.edu
Davis E. Hill, Pennsylvania State University Has since retired
Dennis J. Murphy, Pennsylvania State University – Has since retired
J. Samuel Steel, Pennsylvania State University (Has since retired)
Aaron M. Yoder, University of Nebraska Medical Center – aaron.yoder@unmc.edu

Grain Dust Explosions

(Source: Penn State Ag Safety and Health)

 

Use the following format to cite this article:

Grain dust explosions. (2012) Farm and Ranch eXtension in Safety and Health (FReSH) Community of Practice. Retrieved from http://www.extension.org/pages/63142/grain-dust-explosions.

 

Grain dust explosions of any size can cause damage to equipment, reduced work time, and injury or death. By controlling grain dust emissions, you can provide a cleaner and safer work environment for your employees and community.

Grain dust is highly combustible, so a fire or an explosion can happen at a large grain-handling facility or in a grain-storage area on a local farm or ranch. Four basic elements must be present for a grain dust explosion to occur: fuel, oxygen, confinement, and an ignition source.

  • Fuel:  dust particles from wheat, oats, barley, or other types of grain that are suspended in the air or layers of grain dust in a confined space
  • Oxygen: normal oxygen levels and a continuous air supply
  • Confinement: areas of confined space such as grain bins, basement tunnels, bin deck galleries, silos, downspouts, and enclosed drag conveyors
  • Ignition source: short circuits, static electricity, lit cigarettes or lighters, overheated bearings, friction, cutting torches or welding devices, grinder sparks, lightning, and so on

Explosiveness of Grain Dust

The explosiveness of dust from different types of grain depends on the dust’s minimum explosive concentration (MEC), a measurement of particle size and energy nature. The accepted MEC for grain dust explosions is approximately 0.05 oz. per cu. ft. The optimum explosive concentration (OEC) equates to about 10 times the MEC, approximately 0.5 to 1.0 oz. per cu. ft. The MEC and OEC measurements vary depending on the type of grain. In an enclosed space with a height of 2 ft., the minimum depth of dust that can lead to explosion is 0.002 to 0.004 in. A typical sheet of paper is approximately 0.004 in. thick, so that critical MEC level can be reached in a very short time. Maintaining grain dust  levels at or below the MEC reduces the risk of explosion and increases visibility for workers.

Characteristics of a Dust Explosion

There are two phases in a major dust explosion: a primary explosion and a secondary explosion. The explosions, however, can happen almost simultaneously, so distinguishing between the primary and secondary explosions can be difficult. The dust from the first explosion may actually provide fuel for the secondary explosion by shaking loose settled dust. If fuel, oxygen, and an ignition source are present in a confined space, a series of destructive explosions can occur that may cause structural damage.

Most grain dust explosions occur at grain transfer points. At the transfer points, the movement of grain causes dust to be released at high levels, resulting in suspended dust particles. The suspended dust may collect in leg boots and elevator legs. Dust concentrations in bucket elevators can exceed MEC levels and pose the risk of explosion. 

Preventing Grain Dust Explosions

To reduce the risk of a grain dust explosion or fire, focus on controlling dust and reducing the sources of ignition. Preventative measures include continuous housekeeping, sanitation, and regularly scheduled maintenance. Implement a housekeeping or sanitation program to decrease grain dust in all work areas. Leg boots should be cleaned routinely to remove excess dust and kernels. Additional preventative steps include:

  • Developing and implementing a routine lubrication plan for bearings on the basis of the manufacturer’s recommendations
  • Developing and implementing a standard operating procedure (SOP) for housekeeping practices to minimize grain dust accumulation
  • Using a food-grade mineral spray on grain that is being transferred
  • Installing a bearing-temperature monitor in strategic locations throughout the grain handling system and implementing a program to periodically monitor bearing temperature
  • Installing belt-rub sensors inside bucket-elevator leg casings
  • Substituting steel cups with plastic cups in elevator legs
  • Using antistatic belting material in legs and horizontal belt conveyors
  • Establishing easy-to-open cleanout doors in the leg-boot side panel for easy removal of grain and dust
  • Installing dust aspiration systems or a ventilation system at grain transfer points
  • Training employees in safe work practices so that they can recognize and prevent hazards that could lead to a grain dust explosion
  • Posting No Smoking signs and actively enforcing the rule
  • Completing regularly scheduled inspections to locate any defective wiring or sparking and make repairs as needed
 

Use the following format to cite this article:

Grain dust explosions. (2012) Farm and Ranch eXtension in Safety and Health (FReSH) Community of Practice. Retrieved from http://www.extension.org/pages/63142/grain-dust-explosions.

 

 

 

Sources

Combustible dust in industry: Preventing and mitigating the effects of fire and explosions. (2005) United States Department of Labor, Occupational Safety and Health Administration. Retrieved from http://www.osha.gov/dts/shib/shib073105.html.

Grain handling. (n.d.) United States Department of Labor, Occupational Safety and Health Administration. Retrieved from http://www.osha.gov/SLTC/grainhandling/index.html.

Jones, C. (2011) Preventing grain dust explosions. Oklahoma State University Cooperative Extension Service. Retrieved from http://pods.dasnr.okstate.edu/docushare/dsweb/Get/Document-2604/BAE-1737web.pdf.

 

Reviewed and Summarized by:
Linda M. Fetzer, Pennsylvania State University – lmf8@psu.edu   
LaMar Grafft, East Carolina University – grafftl@ecu.edu
Davis E. Hill, Pennsylvania State University (Has since retired)
Carol Jones, Oklahoma State University – jcarol@okstate.edu
Dennis J. Murphy, Pennsylvania State University (Has since retired)
Aaron M. Yoder, University of Nebraska Medical Center – aaron.yoder@unmc.edu

Manure Foaming

Foaming Manure

Foaming Manure – Source: Schimdt, UMN.

 

Use the following format to cite this article:

Manure foaming. (2012) Farm and Ranch eXtension in Safety and Health (FReSH) Community of Practice. Retrieved from http://www.extension.org/pages/63144/manure-foaming.

 

Foam in manure pits can be a danger both to animals and workers around the pits. Manure foaming occurs primarily in hog facilities, most commonly in the midwestern United States and Canada. The causes of manure foaming remain a mystery. Manure foaming is not predictable, and no known solutions work in every situation. It is therefore important to understand the risks posed by foaming manure and ways to reduce those risks.

Foam is defined as a mass of bubbles of gas on the surface of a liquid. Rather than being crusty or fluffy, foaming manure has a thick, mucous consistency. In manure pits, the bubbles do not burst but rather cling together.

One theory suggests that a specific microbial population causes foaming in manure pits. Another theory suggests that filamentous microorganisms (bacteria, fungi, or algae) are the cause. Neither theory has been confirmed, and research into the causes of manure foaming continues. Possible triggers include a high content of manure solids resulting from water conservation practices; cool weather patterns; reduced antibiotic use; feeding or diet adjustments; changes in DDGS; changes in corn, including genetic modifications; moldy and/or lightweight corn; and changes in the type or quantity of fat fed to the animals. 

Dangers of Foaming Manure

Foam in manure pits may be linked to suffocation of hogs and incidents of fire and explosion. Methane (CH4) and hydrogen sulfide (H2S) are gases produced during the anaerobic breakdown of manure. Methane is a highly flammable gas that can lead to asphyxiation at high levels. The foam in manure pits captures methane, resulting in concentrations of methane in the foam that can be as high as 60% to 70% (600,000 to 700,000 ppm), which is higher than the concentration at which explosions can occur. When the foam bubbles are disturbed or broken, the captured methane is released at an explosive concentration of 5% to 20% (50,000 to 200,000 ppm). If there is an ignition source near an explosive concentration of methane, an explosion or a flash fire could occur. 

Hydrogen sulfide is a colorless gas that smells like rotten eggs at low levels but can overcome a person’s sense of smell at levels of 100 ppm or higher. Hydrogen sulfide is heavier than air and can collect in the floor or lower areas of the pit. Exposure to hydrogen sulfide can cause eye and nose irritation, headache, nausea, and death.

In addition to the danger of explosion or fire, foaming manure poses an asphyxiation risk for both people and hogs when foam rises through the slats in a barn. Anyone working within the building or in the immediate area should be informed about the dangers of foaming manure, including the hazards of methane and hydrogen sulfide. No smoking should be permitted in or near the building.

Methods of Treatment

There are no proven ways to prevent manure foaming; at present, the focus remains on treating the symptoms. Below are some treatments that have yielded mixed results:

  • Water – Spraying water, running sprinklers, or using soaker systems can break the bubbles in foam, releasing the methane in a relatively safe manner. If you are using water to break down foam, remember to follow recommended ventilation practices.
  • Antifoam agents – There are several antifoam agents on the market. Although some have had limited success in reducing foam, none have proven effective on a consistent basis.
  • Microbial enhancements – Microbial enhancements, typically in the form of feed or manure additives, have been effective on an inconsistent basis.
  • Microbial control – Microbial control refers to changes in pH or oxygen levels or the use of antibiotics.

Due to the unpredictable nature of manure foaming, you should complete an audit of manure pits at least once a month. The purpose of the audit is to monitor pits for changes in manure consistency, increases in foam, and other such indicators of a potential problem. Based on information gathered in the audit, you can make necessary management decisions about using a treatment or changing the pumping schedule.

Emergency Action Plans

Develop an emergency action plan and review it annually with employees. It is especially important that anyone on-site during pit pumping receive training about the action plan. The emergency action plan should include a list of clean-up and containment practices in the event of an overflow, breach, leak, fire, or emergency land application. Due to the potential risk of fire or explosion, include in the action plan an evacuation route for employees. In addition, make sure that all employees know the location of fire extinguishers, hose cabinets, fire blankets, and other types of safety equipment. As a farm or ranch manager, make sure that you have necessary safety equipment and that it is in proper working order.

During pit pumping, remember to keep on hand the contact information of first responders, including the fire department, hospital, and police. When calling 911, give your name, location, contact information, and details about the emergency. 

Precautions during Agitation and Pumping

When foaming manure is present, the risk of explosion necessitates additional precautions during pit agitation and pumping. It is strongly recommended that you pump manure pits when the barn is empty. People should remain outside of the building during agitation and pumping. After checking that everyone is out of the facility, add a physical barrier such as yellow caution tape or place warning signs to ensure that no one enters the facility during the process.

Any ignition sources should be turned off and locked out. Possible ignition sources include welders, heaters, motors, and other equipment, such as a feeding system, that uses electricity. (Because of the importance of ventilation, discussed in the next section, ventilation systems that use electricity may operate during agitation and pumping.) 

Do not agitate the manure until the top of the manure surface is at least two feet below the floor slats. Agitate the manure below the surface of the liquid manure and stop the process if you can no longer agitate below the surface level. Agitate intermittently to reduce the risk of sudden gas release.

When possible, cover pump-out ports unless they are needed for agitation or manure load-out, and cover the pump-out around the agitation with a tarp. After pumping is complete, remember to secure manure pit covers.

Ventilation during Agitation and Pumping

Proper ventilation is one of the most important safety measures during agitation and pumping of manure pits. Regularly check your ventilation system to ensure that it is in proper working condition. Use a ventilation rate of 20 to 30 cfm per animal to dilute the methane concentration below 5%. Ventilation inlets, curtains, and pivot doors should be open during the ventilation process. For naturally ventilated barns, make sure that inlets and outlets are open. Circulation fans used in the summer do not provide the necessary air exchange needed during agitation or pumping, so plan these processes for days when wind is present to increase the amount of fresh air circulating through the building.

Ventilation for Curtain-Sided Barns

Ventilation procedures for curtain-sided barns differ slightly depending on weather conditions. When the weather is warm with winds over 5 mph, run exhaust fans while the curtains are open. On a calm day, the sidewall curtains should remain closed with the fans running. If, however, you are running more than half of the fans, the curtains should remain open during the pumping process. During colder weather, keep the curtains closed while running the exhaust fans.

If you are using a stir fan, use a horizontally directed fan rather than a fan directed downward, to reduce pockets of gas concentrations and to ensure that contaminated gas does not blow back onto hogs. Ventilate for approximately one to two hours after pumping and prior to entering the barn.

Ventilation for Tunnel-Ventilated Barns

During warm or hot weather, run all of the pit fans and a minimum of two tunnel fans. The procedure is slightly different for cold or moderate weather, but you should nevertheless run all of the pit fans and the 36 in. fan and open the tunnel curtain approximately 6 to 12 in. to provide air movement through the entire length of the barn. Remember to reduce the static pressure of the inlet velocity at the tunnel curtain from the regular setting of 800 fpm to 1,000 fpm to a lower setting of 300 fpm to 400 fpm. During both cold and hot weather, partially close mechanized/motorized ceiling inlets to allow air to enter from the tunnel curtain. Ventilate for approximately one to two hours after pumping and prior to entering the barn.

 

 

 

Resources

Click here to watch an informative video by Dr. David Schmidt from Iowa State University Extension about foaming manure pits.

 

Use the following format to cite this article:

Manure foaming. (2012) Farm and Ranch eXtension in Safety and Health (FReSH) Community of Practice. Retrieved from http://www.extension.org/pages/63144/manure-foaming.

 

Sources

Burns, R. & Moody, L. (2009) Literature review – deep pit swine facility flash fires and explosions: Sources, occurrences, factors, and management. Iowa State University Department of Agricultural and Biosystems Engineering. No longer available online.

Foaming manure. (2011) Ontario Ministry of Agriculture, Food, and Rural Affairs. Retrieved from http://www.omafra.gov.on.ca/english/livestock/swine/news/mayjun10a1.htm.

Jacobson, L. (n.d.) Safety measures to prevent barn explosions during pit pumping. University of Minnesota Extension. Retrieved from http://www.agweb.com/article/safety-measures-to-prevent-barn-explosions-….

Rieck-Hinz, A., Shouse, S., & Brenneman, G. (2010) A top ten list: Preparing for fall manure application. Iowa State University, Iowa Manure Management Action Group. Retrieved from http://www.agronext.iastate.edu/immag/info/toptenlist.pdf.

Understanding foam and pump-out safety. (2010) Iowa Pork Producers Association. No longer available online.

 

Reviewers, Contributors and Summarized by:
Linda M. Fetzer, Pennsylvania State University – lmf8@psu.edu
LaMar Grafft, East Carolina University – grafftl@ecu.edu
Davis E. Hill, Pennsylvania State University (Has since retired)
Dennis J. Murphy, Pennsylvania State University (Has since retired)
Ron Odell, Cactus Feeders, LTD. – ron-odell@cactusfeeders.com
Cheryl Skjolaas, University of Wisconsin – skjolaas@wisc.edu
Aaron M. Yoder, University of Nebraska Medical Center – aaron.yoder@unmc.edu

Confined Spaces: Hazards of Manure Gases


Use the following format to cite this article:

Confined space: Hazards of manure gases. (2012) Farm and Ranch eXtension in Safety and Health (FReSH) Community of Practice. Retrieved from http://www.extension.org/pages/63141/confined-spaces:-hazards-of-manure-….

The Occupational Safety and Health Administration (OSHA) defines a confined space as a space that:

  • is large enough for a worker to enter and complete a task in,
  • has limited or restricted means of entry or exit, and
  • is not designed for continuous human occupancy.

Confined spaces on a farm or ranch in which manure handling may occur include manure pits, manure transfer pipes and deep gutters, transfer storage areas, and liquid manure spreaders. Farms and ranches continue to expand their operations to include larger manure handling systems. While these new systems are more efficient and reduce manual labor, farmers and ranchers must understand the hazards associated with working in and around confined spaces where manure is stored.  

Gases inside Manure Storage Areas

The breakdown of manure is a biological process, and environmental factors such as temperature, humidity, and air flow can impact the release rate of gases produced during this process. High temperature, lack of air exchange, and humidity can increase the levels of manure gases that are produced and released. The following hazardous gases form naturally in manure storage areas and are difficult to detect because of their properties, impact on a person’s sense of smell, and similarity to other odors on a farm or ranch:

  • Ammonia is found in manure pits or aboveground tanks used for manure storage and has a strong odor that can irritate a person’s eyes or respiratory system.
  • Carbon dioxide is a colorless and odorless gas associated with animal respiration and manure decomposition. Carbon dioxide can replace the oxygen in a confined space. If you breathe in air that contains high levels of carbon dioxide, this gas can replace the oxygen in your bloodstream and may result in headaches, drowsiness, and death (after prolonged exposure). Carbon dioxide is heavier than air, so it can easily accumulate in low-lying areas of confined spaces.
  • Hydrogen sulfide is a colorless gas that smells like rotten eggs at low levels but can overcome a person’s sense of smell at levels of 100 ppm and higher. Exposure to hydrogen sulfide can cause eye and nose irritation, headache, nausea, and death (after prolonged exposure). Hydrogen sulfide is heavier than air, so it can easily accumulate in low-lying areas of confined spaces.
  • Methane is a colorless and odorless gas produced during the decomposition of manure in storage. This gas is flammable and potentially explosive, especially when captured in foam that can form on the surface of stored manure. Methane is lighter than air, so it does not accumulate in low-lying areas of confined spaces.

Handheld gas detection equipment should be used to monitor gas levels prior to entry into and while occupying confined-space manure storage areas. Some equipment used to detect manure gases is configured to measure oxygen level, explosive gases (methane), and toxic gases (hydrogen sulfide).

For each of the hazardous gases mentioned above, OSHA has identified safe exposure levels for humans. Table 1 outlines the acceptable exposure limits in ppm over an eight-hour period. The oxygen level in a given space should be between 19% and 23%.

Table 1: Acceptable Exposure Limits
Hazardous Gas Acceptable Exposure Limits
Ammonia 50 ppm
Carbon dioxide 5,000 ppm
Hydrogen sulfide 10 ppm
Methane 1,000 ppm

One way to reduce levels of hazardous gases is to ventilate the manure storage area using a mechanical ventilation system that forces fresh air into the space, increasing the oxygen level and decreasing the levels of explosive and toxic gases. By using a specially designed positive-pressure mechanical forced-air ventilation system, you can reduce the buildup of dangerous levels of gas. Forcing fresh air through a fan into the storage area reduces the possibility of fire or explosion caused by explosive gas coming into contact with electric fan motors. Fans should be able to move a volume of air equal to one-half the volume of the empty manure storage area every minute. Use the ANSI/ASABE S607 standard, provided by the American National Standard Institute (ANSI) and American Society of Agricultural and Biological Engineers (ASABE), for guidance about ventilation capacity and ventilation time prior to entry and during occupancy. Click HERE for more information from Penn State Extension about the standard. To avoid the failure of a critical ventilation system during a power outage, connect the system to a standby power source that is regularly maintained and tested.

Entering Confined-Space Manure Storage Areas

If possible, avoid entering confined-space manure storage areas. If entry is unavoidable, you should fully understand the risks of entering such a space and have an entry plan that outlines your actions.

Complete the following steps when entering and working in a confined-space manure storage area:

  1. Test the oxygen and explosive and toxic gas levels from outside the manure storage area. 
  2. Prior to entry and during occupancy, use a positive-pressure ventilation system to ventilate the manure-storage area.
  3. Prior to entry, lock out all power sources other than the positive-pressure ventilation system to reduce the risk of stray electricity.
  4. Wear an adjustable body harness with a lifeline attached to a rescue and retrieval system and carry a portable gas monitor.
  5. Assign a second person to remain outside of the manure-storage area in case he or she must implement the rescue and retrieval system or get additional assistance.
  6. Maintain verbal and visual contact with the person outside the manure storage area. The person outside the storage area should not enter the area, even in the event of an emergency.
  7. Retest the air quality continuously during occupancy to monitor gas levels.

Additional Safety Recommendations

  • Remember that youth under the age of 16 are prohibited from working in confined spaces.
  • Post warning signs about the risks of confined spaces and gas hazards on or near all manure storage locations.
  • Instruct family members and employees about the hazards associated with manure storage in confined spaces. Even though most agricultural operations are not covered under OSHA regulations for confined-space entry, confined spaces exist in production agriculture, and it is vital that every person associated with the farm or ranch receive training on the hazards. 
  • Prepare and document an entry plan for confined-space manure storage areas. Inform family members and employees about the plan.
  • Provide annual training for family members and employees about the entry into and emergency procedures associated with confined manure storage spaces.
  • Restrict access to confined spaces to authorized individuals. Remove temporary access ladders, and restrict access to permanent ladders.
  • Be aware that personnel and animals may need to vacate the confinement building during manure storage agitation or pumping.
  • Prohibit smoking in and around manure storage areas.
  • Operate manure agitators below the surface of liquid manure to reduce the release of manure gases.

See the Penn State Extension video below to learn more about safety concerns associated with manure storage in confined spaces.

Use the following format to cite this article:

Confined space: Hazards of manure gases. (2012) Farm and Ranch eXtension in Safety and Health (FReSH) Community of Practice. Retrieved from http://www.extension.org/pages/63141/confined-spaces:-hazards-of-manure-….

Sources

Confined spaces. (n.d.) United States Department of Labor.  Retrieved from http://www.osha.gov/SLTC/confinedspaces/index.html.

Harshman, W., Yoder, A., Hilton, J., & Murphy, D. (2004) Confined spaces. HOSTA task sheet 3.8. National Safe Tractor and Machinery Operation Program. Retrieved from http://www.extension.org/sites/default/files/NSTMOP%20Task%20Sheets%20Se….

Harshman, W., Yoder, A., Hilton, J., & Murphy, D. (2004) Manure storage. HOSTA task sheet 3.11. National Safe Tractor and Machinery Operation Program. Retrieved from http://www.extension.org/sites/default/files/NSTMOP%20Task%20Sheets%20Se….

Steel, J., Murphy, D., & Manbeck, H. (2011) Confined space manure storage hazards. Penn State Extension. Retrieved from https://extension.psu.edu/confined-space-manure-storage-hazards.

Zhao, L. (2007) How to work safely around manure storage. Ohio State University Extension. No longer available online.

 
Reviewed and Summarized by:
Linda M. Fetzer, Pennsylvania State University – lmf8@psu.edu    
LaMar Grafft, East Carolina University – grafftl@ecu.edu
Davis E. Hill, Pennsylvania State University – deh27@psu.edu
Carol Jones, Oklahoma State University – jcarol@okstate.edu
Dennis J. Murphy, Pennsylvania State University – djm13@psu.edu          

J. Samuel Steel, Pennsylvania State University (Has since retired)