Wilkins Valve 375XLRP

Open by-pass valve "B" very slowly until differential gauge needle starts to drop

Observe the gauge reading at the moment the first discharge is noted from the relief valve

Record the opening differential pressure of the relief valve

Close test cock #4, and disconnect "VENT" hose from test cock #4

Open by-pass valves "B" and "C" bleeding to atmosphere, then close by-pass valve "B" restoring the system to normal static condition

Observe the pressure differential gauge and note this as the #1 check valve PSID

Is the static pressure drop across #1 check valve greater than the relief valve opening point and at least 5.0 psid?

Clean all parts thoroughly with water after disassembly

Close inlet and outlet shut-off valves

Open No. 2, No. 3 and No. 4 test cocks to release pressure from valve

Unscrew 4 screws holding body down and lift valve body upward

Twist and remove sleeve from body

Push in outlet end of body to slide out both checks from the body inlet

Twist spring retainers counter-clockwise to remove from seat and access poppets

Inspect the rubber seal ring for cuts or embedded debris

Remove screw and seal ring retainer to remove seal ring

Remove bolts and relief valve module

Ensure small and large o-rings are not lost

Inspect diaphragm and replace parts if necessary

Ensure stem assembly is handled carefully due to internal spring load

Inspect and replace o-ring between module and check body if necessary

Apply grease to the o-ring and place on step on check body