July 2013 – The mysterious pig barn fires of North America

Anyone who’s experienced a piggery fire will know it’s one of the most harrowing experiences you can have. Having lost a number of sows and litters myself, the thought is never far away from your mind. The squeals, and the acrid smoke that prevented entry to the piggery, are still vivid memories, along with the charred remains once the fire was out.

I was reminded of this by a TV programme called The Pig Bang Theory that featured a number of unexplained fires that had gutted large pig barns in the United States  and Canada.

There were several theories. The ideas that it might be an arsonist, or the farmers themselves setting fire to the building to claim insurance, were quickly quashed. The next thing was to look at dried brewers’ grains being put into the rations, as the price of wheat, maize and soya were at an all-time high. A bulky food of that constitution would produce more manure and more methane gas. So could it be an electric fault triggering off an explosion by igniting the gas from the slurry?

It seemed strange that most of the buildings were new-ish and of similar design, holding 1,000 finishers or, in some cases, double that number. The insurance companies were obviously worried so came in with thermal cameras and aimed them at control panels that showed extremely high temperatures inside some of them.

Slurry was being stored under the piggeries in these new designs, and sometimes for up to a year before it could be pumped out and spread. Corrosive hydrogen sulphide from the slurry had rusted some of the metal components, which apparently meant that sparks could be formed. Along with the inflammable methane gas, this was a disaster waiting to happen.

They looked at the buildings’ ventilation systems and redesigned them to take out as much gas as possible, but still the fires started. They inserted vents above the stored slurry to get even more gas out then on some units, but then another problem occurred. The slurry started foaming and would well up between the slats and block the ventilation shafts. Tests on what the foaming was were more or less inconclusive, but they began to think that the foam was holding more methane and if it popped, as it tended to do, it would release more methane than normal. The slightest electric fault or spark, and the rest was history.

One owner had travelled the world to seek an alternative and it looked as if she finished up with no wood at all in the barns and no lights or power either! Perhaps she should have visited our building manufacturers here; they don’t (touch wood) seem to have that sort of problem, and we also have a lot of slurry stores and very few if any would leave their slurry under the pigs for a year.

It was an interesting programme, but devastating for those affected, one producer was, in fact, burnt out twice. Suffice to say he’s no longer a pig producer.

> Yorkshire farmer Sam Walton is a former pig producer and the founding editor of Pig World.

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