Ushookup info

Because of this flow of water, the pressure upstream of the RP is now great enough to cause the check valve to open and flow water to the fixture demanding water.

Ushookup info-78

Once in this area, the water enters a relief valve sensing line.

Some sensing lines are external hose or pipe, and some utilize an internal passageway.

Let us hook up our RP to a water source, which delivers 100 PSI, and begin to pressurize the backflow prevention assembly.

Relief Valve As the inlet shut-off is opened, water enters the upstream side of the backflow prevention assembly body ahead of the 1st check valve.

During the normal flow of water through a properly working RP backflow prevention assembly, the relief valve will be pressured closed, and the check valves will modulate between an opened and closed position to fill the water demand of the plumbing system.

The two check valves (1st & 2nd Check) will have different spring loadings.

Once the water pressure has closed the relief valve, then the pressure will increase to the next point, which will cause the first check to open, and allow the water to travel past the first check valve.

1st Check Valve The water pressure will be reduced by the amount of pressure it takes to open the first check spring loading.

Reduced Pressure Principle Backflow Prevention Assembly (RP) To understand what happens inside an RP, let us flow water through a generic backflow prevention assembly.

An RP consists of inlet and outlet shut-off valves, four properly located test cocks, a first and second check valve component, and a relief valve component.

From this data, we cannot say how the backflow prevention assembly worked yesterday or if it will work tomorrow, only what it is doing right now.

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