

Farm and Country Finance comments on the dangers of Slurry Tanks

In the light of recent and very sad events, can we remind you all of the need to be careful around slurry tanks. Here is the text of the NFU’s guidance on this.

What is Slurry gas?

Slurry gas is a mixture of gases including methane, carbon dioxide, ammonia and hydrogen sulphide. The gases are produced by bacteria during the decomposition of slurry. Hydrogen sulphide gas is formed within the slurry in the tank. Some gas may bubble to the surface but most remains dissolved in the liquid in a similar way to gas held within a bottle of ­fizzy drink. When the slurry is mixed, the gas is released very quickly. The addition of other materials such as silage effluent may increase the quantity of gas produced.

Slurry Gas can kill

There have been a number of high pro­file incidents recently where slurry gas has resulted in death of people and animals. Hydrogen sulphide, the most deadly slurry gas, is odourless in high concentrations. It also causes dif­ficulty in breathing, then disorientation. Collapse and death can occur after only a few breaths. Drowning has also occurred where people have fallen through openings into tanks. Slurry gas is dangerous because it displaces air from your lungs and also affects the nervous system. Slurry gases are also highly flammable. Slurry gases releases are unpredictable. The levels normally rise as soon as mixing starts with the fi­rst 30 minutes being the most dangerous. The level will generally fall as the mixing continues. Every time the pump is repositioned to mix another part of the tank, the levels will rise again. Leave for at least 30 minutes again (longer may be required for larger tanks). Don’t rely on meters they can lead to a false sense of security. They need to be maintained and may need calibrating, they may also warn you too late. Face masks don’t work. Only full breathing apparatus is effective.

Safety Precautions

1. If possible, mix on a windy day.

2. Keep children away from the area at all times when working with slurry.

3. Take all animals out of the building before starting to mix slurry.

4. Open all doors and windows.

5. Use outside mixing points ­first.


7. Start the pump/mixer and then stay out of the building for as long as possible – at least 30 minutes or longer depending on the size of the tank.

8. If you have to go into the building make sure that another adult who knows what you are doing, stays outside the building and can get help if needed.

9. If you have to re-enter the house to move the pump, or change the direction of the pump, then you need to leave the building as soon as this is done. Do not go back in for as long as possible – at least another 30 minutes or longer depending on the size of the tank.

10. Avoid naked ‑ flames, as slurry gas mixture is flammable. 11. Do not stand close to the pump/exhaust of a vacuum tanker when it is being ­filled.

In an emergency

If possible stop the pump and get the person to fresh air.

Don’t put yourself at risk, people die trying to save others.

Call 999 and tell them slurry gas may be present.

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