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How Are Pressure Reducing Valves Affecting Your High-Rise Fire Safety?

Jeff Harper, PE

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Sep 6, 2019

In 1991, three fire fighters were killed in a fire at One Meridian Plaza in Philadelphia because the building standpipes, which were equipped with pressure reducing valves (PRVs), weren’t properly set and failed to provide the needed pressure for their hose lines—leaving them in a burning building with an impaired fire-fighting system.

A PRV is a mechanical device that is installed into a sprinkler and/or standpipe design in many high-rise buildings. PRVs help to control pressure, which is extremely important in high-rise buildings where, because of gravity, pressure can build up significantly on the lower floors of a sprinkler or standpipe piping zone. If PRVs are not properly inspected, maintained, and tested, they can be a danger to fire fighters as well as the building occupants. The PRVs limit the system pressure (typically below 175 psi) below that which most sprinkler and standpipe system components are commonly designed to withstand.

Mandatory requirements to include the fire protection system infrastructure within the building to perform full flow testing of PRVs did not appear in NFPA 13 until the 1999 Edition. The 2003 IBC (which references the 1999 edition of NFPA 13) was not likely used in most buildings until 2004 at the earliest. This means that high-rise buildings built before 2004 that were equipped with PRVs may not have system infrastructure in place within the building to easily facilitate the necessary periodic testing and maintenance as required by NFPA 25 Inspection, Testing, and Maintenance of Water-Based Fire Protection Systems.

How Do You Properly Maintain PRVs?

Because PRVs are a mechanical device, they need to be properly inspected, maintained and tested to ensure they function as intended. There are multiple types and intended uses of PRVs. Below are some example steps to verify PRVs are functioning as intended:

  • Conduct quarterly inspections to ensure inlet and outlet pressures are indicating as intended, valves are in the correct open or closed position, handwheels are in place and hose threads are in good condition.
  • Conduct partial flow testing annually to move the valve seat from the closed position.
  • Conduct full flow test of each PRV every five years.

Do I Really Need to Maintain my PRVs?

In fire sprinkler systems, water isn’t normally intended to be flowing through a system daily. Also, corrosion and mineral deposits can build up over time. Regular maintenance moves water through the PRV to keep them in a functional state and minimize potential build-up.

Inspecting quarterly (which can be performed by building engineering staff) is critical to ensuring inlet and outlet pressures at each valve are staying consistent and in-line with the originally designed pressures for each of the valves. Because the pressures in the fire protection system change from one story to the next in a high rise, each PRV will have varying pressure reduction differentials—performing a slightly different amount of work than the one on the next story.

All three steps in the inspection, testing, and maintenance process are necessary and crucial to ensure the valves operate and are properly set to perform the jobs intended by their design.

In the event of a fire, your building’s sprinkler or standpipe system needs to perform as intended. No matter the age of your building, you should be regularly inspecting, maintaining, and testing your PRVs. As experts in fire systems design and maintenance, we can help ensure your high-rise is code compliant by providing guidance and/or witness testing of these important devices.