Testing pressure-regulating standpipe hose valves
My April column on the One Meridian Plaza Fire discussed the fire’s impact on the use of pressure-regulating hose valves on standpipe systems. To recap, a finding from the NFPA Fire Investigation 1 stated,“Investigators determined that the PRVs on the standpipe system were not properly adjusted. As a result, initial fire crews did not have adequate water to suppress the fire, and the fire reached such severe magnitude that it spread unimpeded from floor to floor until extinguished by the automatic sprinkler system on the 30th floor.”
Note: Fire Investigation Report, One Meridian Plaza Philadelphia, Pennsylvania Three Fire Fighter Fatalities February 23, 1991, Thomas J. Klem, Director of Fire Investigations National Fire Protection Association.
In May 1991, NFPA released Alert Bulletin 91-3, “Pressure Regulating Devices in Standpipe Systems.” The major recommendation from this report was, “Fire departments should begin to check every standpipe equipped building within their jurisdiction for the presence of pressure regulating devices. Further, they should become thoroughly familiar with the function of the various pressure regulating devices. If they find such devices, they should immediately contact the building owner and verify that the devices have been properly selected, installed and adjusted to deliver the pressures and flows needed for firefighting purposes. Information on the inspection, testing and maintenance of standpipe systems is contained in NFPA 14A.”
The standards were immediately revised to require testing for pressure-regulating devices. And for years, we have been trying to figure out how to properly test these devices, particularly the PRV hose valves. Now, there is readily available, off-the-shelf equipment that can be used. Before I tell you about that, let us look at the testing requirements.
NFPA 14 (2016) requirements for system acceptance testing of pressure-regulating devices are contained in Section 11.5.5. Paragraph 188.8.131.52 states, “Each pressure-regulating device shall be tested to verify that the installation is correct, that the device is operating, and that the inlet and outlet pressures and flow at the device are in accordance with the design.”
The sample, “Contractor’s Material and Test Certificate for Aboveground Piping,” in NFPA 14 contains a table in which test data for each PRV must be recorded. The data includes: location and floor; model; pressures at PRV inlet and outlet for the non-flowing condition; and pressures at inlet and outlet for the flowing condition and the flow in gpm.
Please pay attention to the following annex note that cautions testing to cover the anticipated range of flows. This is important for pressure-regulating floor control valves controlling sprinkler systems.
“It is important to test pressure-regulating devices at the maximum and minimum anticipated flow rates. Minimum flow can be from a single sprinkler for combined systems or flow from a 11∕2 in. (40 mm) hose connection on standpipe systems that do not supply sprinklers. This can require a sustained flow to demonstrate the continued performance of the pressure-regulating device at the minimum flow rate,” (A.184.108.40.206 ).
Author’s disclaimer: Do as I say not as I do. What I do in the case of testing pressure-regulating sprinkler floor control valves is to use the sprinkler test/drain connection to do one flow at the test rate (one sprinkler) and one flow with the drain valve fully open.
Now regarding inspection, testing and maintenance of pressure-regulating valves, NFPA 14 Chapter 13 refers one to NFPA 25. All well and good, but not much help in NFPA 14 as to actually how do the testing of PRVs. Let us take a look at NFPA 25 (2014) for inspection, testing and maintenance requirements. Table 220.127.116.11 requires the pressure regulating valves on hose connections and sprinkler systems be tested every five years.
Paragraph 18.104.22.168 requires full flow testing of pressure regulating hose valves every five years. The annex note to this paragraph provides the following guidance, “PRV devices can be bench tested in accordance with the manufacturer’s instructions or tested in place. To test in place, a gauge is connected on both the inlet side and the outlet side of the device, and flow readings are taken using a Pitot tube or a flowmeter. Water is discharged through a roof manifold, if available, or through hose to the exterior of the building. Another acceptable method for systems having at least two risers is to take one standpipe out of service and use it as a drain by removing PRV devices and attaching hoses at the outlets near the ground floor level. When testing in this manner, a flowmeter should be used and a hose line utilized to connect the riser being tested and the drain riser,” (A.22.214.171.124 ).
This guidance is similar to the testing guidance provided in Alert Bulletin 91-3. Here is an opportunity for someone to submit a proposal with updated guidance. Bench testing seems time-consuming and impractical. Perhaps, many of you out there have known how to test the PRV hose valves in place and have been doing so for many years. We have not figured it out until recently.
As noted in the NFPA 14, “Contractor’s Material and Test Certificate for Aboveground Piping,” three measurements are required, pressure upstream of the PRV hose valve, pressure downstream of the PRV hose valve and total flow. The pressure upstream is the easy one. A permanent gauge or a connection for a gauge can be provided at the standpipe riser near the hose valve. Obtaining the other two measurements were the problem.
Since the 1993 edition of NFPA 14, standpipe risers equipped with pressure-regulating hose valves have required a three-inch test/drain riser with minimum 2-1/2 inch test connection points on every other floor. That solved the issue of where to put the test water for hose valves far from the roof or the ground floor.
The problem has always been how to obtain the flow rate. Well, now there are commercially available devices that are essentially flow tubes with an internal flow meter and a downstream pressure gauge connection.
The photo shows such a device. The test device consists of a female swivel hose connection on an elbow, the flow tube with the downstream pressure gauge, a flow meter and a hose valve. The flow meter is similar to those provided for fire pumps systems. There is a straight 2-1/2 inch hose valve at the end of the device. This hose valve can be used to adjust the flow through the tube. One can then connect the required length of 2-1/2 inch hose and run it up or down the stairs to the drain riser connection. Problem solved.
If you are testing, or witnessing the testing of PRV hose valves, make sure adequate time is allocated. Testing all the pressure regulating hose valves in a large high rise building can take several days.
As with any flow testing involving very high pressures, safety is of paramount importance. Always make sure the connections are tight and that the hose can handle the expected pressures. In general, do not locate important body parts in front of high pressure outlets when the fire pumps are running. In new construction where stair lighting is not yet functioning, make sure temporary lighting is available.
As an added bonus I have included two photos that show the test set-up for an in-line system riser pressure-regulating valve using hose monsters.
Samuel S. Dannaway, P.E., FSFPE is a licensed fire protection engineer and mechanical engineer with bachelor’s and master’s degrees from the University of Maryland Department of Fire Protection Engineering. He is a past president and fellow of the Society of Fire Protection Engineers. He is vice president of Fire Protection Technology at Coffman Engineers Inc., a multi-discipline engineering firm with over 360 employees across eight offices. Dannaway can be reached at dannaway@ coffman.com.