Posted By A.A Hi all, A problem has occured in a water based fire fighting system (Water Spray), I will give you a description about it & any comment on this is highly appreciated: The system is composed of Water Storage tank, pumps set (Jockey pump (work automatically at 5.5 bar), Electric (work automatically at 5 bar)& Diesel(work automatically at 4.5 bar)), deluge valves, sprinklers detection line & the water dischrage nozzels. The system pressure is 10 bar. This system starts losing pressure, the matter which lead to repeated operation of the jockey pump (each minute), (the pressure dropping to 5.5 bar the jockey starts & compensates it to 10 then it stops -- the pressure drops again & so on). What I've did: 1- Inspected the line (above ground) -- NO LEAK, 2- Closed the delivery valve -- Pressure still dropping, What I knew now that the problem is inside the pumps room, where I do not know. (Note: there is no leak in pumps conection). Now I am thinking about the non-return valves which connected at the delivery part of the pump set, and my question is: IF there is a defect in a non-return valve does this lead to such pressure drop? I hope that my description is clear (I am not so good in English langauge) Thanks in advance, A.A

Posted By Merv Newman AA there is usually a clappet valve on the main line after the pumps. This could be letting back. Nothing you can do. As the man said, get the experts in. It may lead to shutting down the sprinkler system for a number of hours. Inform your insurance people before hand. Also inform employees of reduced fire protection. Ask them to be extra careful and on the alert. In any case, think about what you can do to maintain decent fire FIGHTING capabilities while your main system is down. Inform the fire brigade. If your situation is high risk then they MIGHT be able to supply a standby crew and engine during the intervention. This may or may not be a free service but in any case you pay for the beer. (and/or a donation to widows and orphans) Merv