i have a zone that - when turnd on by timer or manually only about 1 foot of spray comes out of sprinkler heads (used to wk fine). When i turn the ittle screw on top of valve (its about the size of a dime) water pressure comes up and wks fine - only water leaks at screw and when zone comes on next time NO pressure??? metal valves were just replaces about 1 yr ago.
It's hard to say exactly what's wrong without knowing what type of valves you have since different valves have different components. In any case, I'd start by checking that the bleed screw and/or handle (depending on type) and that the flow control screw or handle (again depends on what make/model you have) to make sure they are in good condition and properly set. Be careful when turning these screws or handles don't force them past the normal stopping points. If that all checks out, there may be some dirt or debris stuck in the valve that's not allowing the diaphragm to open all the way.
No. that's not gas tight and the plastic factors would possibly no longer delight in the petroleum ecosystem. you will choose a valve it is meant for propane. And the suitable valve would matter on the rigidity the place you meant to place in the valve interior the line. you will additionally would desire to layout the entire element very intently - no open touch relays - to steer away from a spark that would spark off errant propane.