After reading my post from last week on pit foaming safety, Dr Jay Harmon, extension ag engineer at Iowa State University asked me about spark ignition furnaces.
Thanks Jay for catching what I missed. According to LBWhite, their spark ignition furnace will try to light 3 times before it locks out for failure to light, even if the gas is turned off. This is a potential ignition source when foam from manure storage pits is knocked down (broken) that I overlooked.
If you have a spark ignition furnace before you begin to break up the foam, turn off the electric circuit to the furnace or unplug the furnace so it does not try to light if the controller calls for heat in the room.
As I wrote last week, to reduce/prevent the risk of explosion from methane accumulation as a result of breaking of the foam ‘bubbles’, all sources of potential gas ignition must be turned off. While pilot lights on furnaces are the most obvious sources, spark ignitors are just as likely to cause an explosion under the right circumstances.
Hi Dr. Brumm. I have one question. There are many problems with air quality and safety with deep pits. Why the deep pit swine facilities are still popular in USA?
The simple answer is they are the cheapest and easiest to permit. The vast majority of swine units in the midwest use the stored manure as a nutrient source for corn and soybeans. To prevent nitrogen loss the manure is stored in an anaerobic deep pit. If this pit was constructed outside of the building (such as Smithfield’s use of SlurryStore structures), cost per pig increases since you have to build a structure under the slats to capture the manure and then do the transfer, etc. Minnesota does not allow any earthen storage of swine manure so the outside structure must be concrete or something similar.
In the local zoning fights over permitting, putting the pit under the building takes up the smallest footprint on-site and as a concrete structure – there is zero discharge.