How does a water pressure regulator work?

[Seth David Montgomery]

My home has a fire sprinkler system built into it and has a gauge to monitor pressure. The water pressure is unregulated to this system and line pressure is at 150 psi. With the 3/4 valve on the other side of the the system is wide open, the gauge drops to 50 psi. Now, the water supply for my house is regulated at 60 psi (different gauge), with no water running. If I turn on the lawn sprinklers the reading drops to 20 psi. My questions is does a regulator suppose to keep a constant pressure or does it just make sure it doesnt go over the set amount?

[David WinkowskiParticipant]

The regulator does both. If the supply volume is adequate, and the supply valve is not partially closed, then the PRV will maintain the set pressure even when water is flowing. If the pressure drops when using water, then the PRV is not opening completely, the supply valve is not completely open, or the supply to the residence is inadequate. Your more important question is whether your fire system is CPVC plastic or copper. If it is CPVC, 150# may to high for safe operation and/or the pressure relief valve should be set at 150# and therefore should be discharging at any pressure surge.: My home has a fire sprinkler system built into it and has a gauge to monitor pressure. The water pressure is unregulated to this system and line pressure is at 150 psi. With the 3/4 valve on the other side of the the system is wide open, the gauge drops to 50 psi. Now, the water supply for my house is regulated at 60 psi (different gauge), with no water running. If I turn on the lawn sprinklers the reading drops to 20 psi. My questions is does a regulator suppose to keep a constant pressure or does it just make sure it doesnt go over the set amount?

[David WinkowskiParticipant]

: The regulator does both. If the supply volume is adequate, and the supply valve is not partially closed, then the PRV will maintain the set pressure even when water is flowing. If the pressure drops when using water, then the PRV is not opening completely, the supply valve is not completely open, or the supply to the residence is inadequate. Your more important question is whether your fire system is CPVC plastic or copper. If it is CPVC, 150# may to high for safe operation and/or the pressure relief valve should be set at 150# and therefore should be discharging at any pressure surge.: : My home has a fire sprinkler system built into it and has a gauge to monitor pressure. The water pressure is unregulated to this system and line pressure is at 150 psi. With the 3/4 valve on the other side of the the system is wide open, the gauge drops to 50 psi. Now, the water supply for my house is regulated at 60 psi (different gauge), with no water running. If I turn on the lawn sprinklers the reading drops to 20 psi. My questions is does a regulator suppose to keep a constant pressure or does it just make sure it doesnt go over the set amount?

[David WinkowskiParticipant]

The fire system is 1 galanized piping with a prv valve set at 150#. The problem I am having is the water pressure to the house drops to 20 psi when the lawn sprinkler system is on. I know that with a 3/4 pipe wide open, unregulated side, the main pressure will not drop below 50psi, so I feel that with the lawn sprinkler system on, the house pressure should not drop below 50 psi, but it does! I had changed the water regulator and it now drops from 60 psi to 28-30 psi. I am thinking about adding a second regulator to the main line for the lawn sprinkler system to fix the problem. Any other ideas?: The regulator does both. If the supply volume is adequate, and the supply valve is not partially closed, then the PRV will maintain the set pressure even when water is flowing. If the pressure drops when using water, then the PRV is not opening completely, the supply valve is not completely open, or the supply to the residence is inadequate. Your more important question is whether your fire system is CPVC plastic or copper. If it is CPVC, 150# may to high for safe operation and/or the pressure relief valve should be set at 150# and therefore should be discharging at any pressure surge.: : My home has a fire sprinkler system built into it and has a gauge to monitor pressure. The water pressure is unregulated to this system and line pressure is at 150 psi. With the 3/4 valve on the other side of the the system is wide open, the gauge drops to 50 psi. Now, the water supply for my house is regulated at 60 psi (different gauge), with no water running. If I turn on the lawn sprinklers the reading drops to 20 psi. My questions is does a regulator suppose to keep a constant pressure or does it just make sure it doesnt go over the set amount?

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