Many of you have read the press reports of the tragic loss of life in a Minnesota nursery when 2 persons died from a fire when they began to power wash the empty room. While the investigation isn’t complete, I’ve worked with both the production company and the insurance company on this situation and the best guess so far is that the explosion was caused by a space heater igniting methane that accumulated as a result of power washing activities bursting the foam bubbles in the manure pit.
As a result of this unfortunate incident, the production company in agreement with the insurance carrier has implemented the following policy for any building/room that has pit foaming and is going to be power washed following removal of the last animal.
1) Before anyone enters an empty room/barn where the pit was known to be foaming, turn the gas off OUTSIDE the building.
2) Turn the ventilation to stage 2 full (100%) and let it run for 30 minutes before entering.
3) Go ahead and do the pre-soak (known to knock down the foam) – but keep the furnaces OFF.
4) After pre-soaking and foam knock-down, keep ventilation at stage 2 for 30 minutes.
5) The production system are buying a methane meter and will then test for methane levels at the furnace before turning the gas back on. Methane is explosive at concentrations of 5-15% of the ambient air.
In general stage 2 fans have about a 2.5-3 minute exchange rate in a nursery or grow-finish barn so 30 minutes of run time should keep methane from knocked down foam from amassing at explosive levels.In the winter, you won’t freeze anything by running fans at stage 2 for only 1 hr without heat.
NEVER weld above a pit that is foaming. The foam is mostly methane and hot sparks falling into the pit can cause an explosion in the pit.
Before agitating a pit that is foaming, turn off the gas outside the building and shut off any electrical circuits that could serve as a spark for methane that would be released from the foam. While fans will be operating, turn off feed lines, lights and electrical outlets to reduce this risk.
Before we get to the fall season when barns are closed up once again I urge every producer, production system and contract grower to review their safety practices associated with foaming pits. You may come up with an even better safety plan than what I’ve outlined above.