What is a pressure test?
It is a way to make sure that liquid and gas will not tank will not leak from the tank, the pipe or the fittings.
Why is it important?
Any biogas system needs to allow the water and gas leaving it to be controlled and tested.
When is it done?
The tank should be pressure tested for liquid leaks before the biogas digester is fed any solids.
The gas connection, pipe and fittings should be tested before the system is fed any solids and it should be tested whenever there is a smell detected away from the digester and when there has been a noticeable decrease in the amount of gas available for cooking
How is it done?
Liquid pressure test.
Fill the tank with water and visually check for leaks out the side or a falling water level (possible leaks out of the bottom). It is extremely rare for this to be a problem, but it still should be done. The water can be left in the tank, as it is needed for the operation of the digester.
Gas pressure test.
Add compressed air into the tank from the gas appliance end up to the recommended pressure ( usually 7kPa or the equivalent of 70cm water height).
This can be done by using a small air compressor
Fill a spray bottle with a mixture of soapy water. Spray the soapy water at each connection, starting at the top of the biogas digester and moving all the way to the gas appliance. Look for bubbles coming out of the joint. Any leaking connection should be tightened first. If tightening does not solve the problem, then undo the fitting, inspect and clean the parts, then reassemble and tighten them.