Proper Ventilation of Confined Space Manure Storage Facilities

Occupational Injury Reduction

The Challenge:

Fatalities due to entry into on-farm confined space manure storage facilities occur each year due to the oxygen-deficient atmosphere as well as toxic and/or explosive gases present. Most deaths occur to persons conducting repair or maintenance on equipment, or to those attempting to rescue another person in the storage facility.


Northeast Center (NEC) researchers introduced a new International Engineering Standard (ANSI/ASABE S607), "Ventilating Manure Storages to Reduce Entry Risks" which has now been accepted. The standard provides ventilation rates, configurations, and air exchange rates required to reduce entry risk for 80-85% of manure storages. If the standard is adopted into new and existing storages, they will have a ventilation system capable of evacuating gases and replenishing oxygen to levels safe for human occupancy from five to greater than 15 minutes.


Forced ventilation has been shown to be an effective way to lower the concentrations of noxious gases to levels safe for human entry into storage facilities. Experimental tests were conducted on rectangular and circular-shaped confined space manure tanks with solid, fully slotted and partially slotted covers.


Tests identified the most efficient evacuation of gases from the tank by optimal placement of the ventilation fan based on type of cover. The higher the air exchange rate, the higher the evacuation of potentially deadly gases from the confined space.

Close-up of confined space manure storage educational demonstration

Researchers developed the new International Engineering Standard (ANSI/ASABE S607), "Ventilating Manure Storages to Reduce Entry Risks" to specify the forced ventilation requirements, including ventilation system layout, air exchange rates, and minimum ventilation times for evacuation of contaminant gases from and replenishment of oxygen into on-farm confined space manure pits prior to entering. A simulator was also developed in order to educate confined space users about hazards, ventilation and measurement of gas concentrations.