Gating Down Pressure Reducing Valves

By Terin Hopkins, Manager of Public Fire Protection
Flowing water from standpipes in high-rise buildings during fire operations is as old as time. For many decades the standard operating procedure included a firefighter opening the nozzle bale fully and a second control firefighter gating down any excessive pressure, by using the handwheel on the standard hose valve. This technique allows the nozzle firefighter to properly apply the desired spray pattern, while delivering the optimum pressure/flow pattern and avoids the bad practice of gating the nozzle down by the bale. Gating the nozzle will provide an ineffective nozzle flow pattern and reduce the proper application of water on fire. This technique must be practiced and coordinated between the nozzle firefighter and the control firefighter for a successful operation.
Well, out with the old and in with the new. In today’s modern buildings, we are seeing more and more pressure reducing valves (PRV’s) installed for firefighter safety.
These valves protect firefighters by reducing system pressures at the hose connection that are greater than 175psi that could lead to firefighter injuries. The valve is constantly attempting to maintain the design specified outlet pressure somewhere between 100psi-175psi, during both static (non-flowing) and residual (flowing) conditions. They are constantly regulating the inlet pressure and adjusting for the proper outlet pressures, based on the individual valve settings.
Long story short, the valve must be in the fully open position to properly operate, and it will not be able to adjust correctly if gated from the handwheel. This means that the control firefighter can no longer gate excessive pressure using the pressure reducing hose valve handwheel effectively. It also means that providing the full flow of the valve without the ability to gate excessive pressure could provide excessive nozzle pressure requiring the nozzle firefighter to use the bale to gate pressure for safety and providing an ineffective spay pattern.
This design change has been a catalyst for the use of inline standpipe manifolds with gauges or flow meters, elbows, and separate gate valves, used during standpipe operations. This added equipment allows firefighters options for more effective line positioning with elbows, the ability to dial in specific pressures with gauges and fully effective nozzle flow patterns. Now the control firefighter can fully open the PRV, allowing the PRV to properly regulate pressure and the separate gate provides the control firefighter an avenue to properly gate any excessive pressure, with the fire service provided gate valve.
The basic operation has not really changed and essentially stays the same, the manifold is connected to the PRV hose connection. The PRV is fully opened, and the same coordination is then done between the control firefighter, using the fire service provided gate to reduce excessive pressure, allowing the nozzle firefighter to fully open the bale of the nozzle and provide a quality water flow pattern.
Successful standpipe operations begin and end with understanding standpipe system design and how to use that design to your tactical advantage. In some cases, the correct equipment must be used to achieve that level of performance.
More about the Author:
Terin Hopkins has 34 years of experience in public safety and is currently the Manager of Public Fire Protection for the National Fire Sprinkler Association. He represents NFSA on many NFPA and UL technical committees, including NFPA 14 Standard for the Installation of Standpipe and Hose Systems.
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