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General requirements of Circulation Relief Valve

Circulation Relief Valve

Circulation Relief Valve
Circulation Relief Valve


A valve used to cool a pump by discharging a small quantity of water. This valve is separate from and independent of the main relief valve.

General Requirements of Circulation Relief Valve:

  • Where an electric variable speed pump is installed, the automatic circulation relief valve shall open at the minimum speed.
  • Each pump shall have an automatic relief valve listed for the fire pump service installed and set below the shutoff pressure at minimum expected suction pressure.
  • The valve shall provide sufficient water flow to prevent the pump from overheating when operating with no discharge.
  • Provisions shall be made for discharge to a drain.
  • Circulation relief valves shall not be tied in with the packing box or drip rim drains.
Note that: Above requirements shall not apply to engine driven pumps for which engine cooling water is taken from the pump discharge.

Location of Circulation Relief Valve:

  • The valve shall be installed on the discharge side of the pump before the discharge check valve.
  • For multistage multiport pumps, the automatic circulation relief valve shall be installed before the discharge check valve for the last port and set below the churn pressure of the first port.

Sizing of Circulation Relief Valve:

The automatic relief valve shall have a nominal size of 0.75 in. for pumps with a rated capacity not exceeding 2500 gpm and have a nominal size of 1 in. for pumps with a rated capacity of 3000 gpm to 5000 gpm.

References of the article:

NFPA 20 - 2019 edition (Standard for the Installation of Stationary Pumps for Fire Protection)


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  3. This is my first visit to your web journal! We are a group of volunteers and new activities in the same specialty. Website gave us helpful data to work. Gate Valve

  4. I have the following queries.

    1) What would the valve do in the normal working with discharge on.

    2) How does this temperature gradient work in the circulation relief valve.

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  8. Is it still applies to end suction pump ?. To my understanding is that the NFPA 20 does not specify any kind of pump regarding to this matter. Does anyone have any other opinion to this ?.

  9. This comment has been removed by the author.

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