Two main concerns when agitating manure are hydrogen sulfide and methane. Both of these gases can build throughout their time in manure storage and can be very harmful to both humans and animals. Knowing the types of gases, safety precautions, and preventative practices when agitating and pumping manure can avoid risks to humans and animals.
Manure Pit Gases
Methane is a product of anaerobic digestion in the lower levels of deep pits and is continually released into the air above the manure. Having a proper pit ventilation system will remove this gas from the air. In foaming pits, methane accumulates in the foam bubbles. During manure agitation and pumping, the foam is disturbed, releasing large amounts of methane in the pit below the slats. There is a risk of the high methane concentrations escaping into the air space above the slats.
As the buildup of gases displaces the air above, an ignition source, such as a heater or an electrical spark, could cause a flash fire and explosion. For more information about methane and foaming pits, see the Michigan State University Extension News article, “Use caution when dealing with foaming manure pits.”
Hydrogen sulfide gas will accumulate in manure foam, as well as in the manure itself. It is released by manure agitation and pumping, just like with methane. In some instances of rapid release or inadequate ventilation, the gas may escape into the livestock confinements above the slats. It can reach concentration levels that are lethal to both humans and animals. Proper ventilation systems can help prevent this.
Preventative Practice #1
Although one might use a maximum pit ventilation system, one or two fans may not be providing adequate ventilation during the pumping process. Pit fans can be covered for the pump-out port and not be used. The open port acts as an air inlet, allowing incoming air to short circuit the barn’s normal air inlet and enter directly into the pit area below the slats. Less air was being pulled down across the slatted floor surface. In certain areas of the barn, gases can rise above the floor into the animal space, causing potentially fatal situations for the livestock. Prevent the pump-out port from becoming an air inlet by covering the opening around the aviator and the pump or hose with a tarp.
Preventative Practice #2
Maximize pit ventilation will not always pull fresh air into the pit evenly across the slatted floor. There are too many openings in slatted surfaces to create an even downdraft throughout the building. The downdraft caused by pit fans is a local effect, meaning more air is pulled down closer to the fans than in other areas. Less air will be pulled down into the pit farther from the fans. This effect of the pit fans can create dead zones in the barn where pit gases can build up in the animal area.
To prevent this situation, maximum pit ventilation should be supplemented by wall fans. During agitating and pumping, the air exchange rate in a barn should be three times the minimum ventilation rate or set no lower than 25 to 30 CFM (cubic feet per minute) per pig. In tunnel-ventilated barns, make sure all air inlets are functioning but partially closed. To compensate for the reduced airflow through the inlets, operators can open the tunnel curtains an additional 6 to 12 inches. In naturally-ventilated barns during cold weather, maximize pit ventilation by opening all ceiling vents and slightly opening the curtain. During warm weather, open the curtain along with setting pit ventilation at maximum levels. If available, run stir fans to ensure good distribution of fresh air throughout the barn.
Preventative Practice #3
Agitate manure in naturally-ventilated barns with curtains open on days when wind speeds are above five mph. The main concern for foaming manure is methane flash fires and explosions, but the bubbles contain a mixture of all manure gases. A sudden increase in hydrogen sulfide and other gasses can be caused by breaking down the foam. Extra caution needs to be taken with foaming pits. Similar to practices used in mechanically-ventilated barns, if available, run stir fans.
Preventative Practice #4
It is recommended to follow the practice of drawing down the manure about two feet before beginning to agitate. In some cases, rooster tailing can occur from the agitation, and the spraying of manure back into the pit increases the number of released gases. To avoid rooter tailing and spraying manure against pit walls and pillars, use only the bottom agitator nozzle. Also, stop agitation when the manure has been lowered to the point where its surface is disturbed.
Safety of Personnel
Exercising caution for all people during the agitation and pumping process is of utmost importance. Remind all employees and other on-site personnel to stay out of the buildings during manure agitation and removal. Make sure that only essential employees and people are present during the process. Inform non-essential employees and people of what is going on and avoid venturing into the building. In addition to informing them, check that all people are out of the building before starting the agitation equipment.
As an extra precaution, implement the use of lock-out tags or signs. This is a system of alerting everyone to the dangers of entering a building during manure agitation and removal.
If you have any questions or are unsure of what to do, feel free to give our knowledgeable team a call-anytime-at 833.655.9200. We encourage you to continue on the path of safety by taking a look at Part 5 of our Safety Guide (Child Safety). For more information about Puck Enterprises, visit www.puck.com.
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