Is the testing of backflow prevention assemblies the same for both domestic assemblies and for assemblies installed on fire protection systems? The correct answer is both yes and no. The field test procedure may be the same but there may be significant differences in the steps a tester takes both before and after the field test procedure is completed. The assemblies may also have differences. Depending on the jurisdictions you are working in, you may see an ASSE 1047 Reduced Pressure Detector Backflow Prevention Assembly (RPDA) or an ASSE 1048 Double Check Detector Backflow Prevention Assembly (DCDA) installed. These may be traditional detector assemblies or type two detector assemblies, which contain a single testable check valve in the bypass portion of the assembly. Other jurisdictions may require the installation of a full-size meter on the fire service, so you may find an ASSE 1015 double check valve assembly or an ASSE 1013 reduced pressure principle assembly installed.
Other differences you will see on backflow assemblies used in fire protection systems are with the number one and number two shutoff valves. These valves must be of an indicating type so you will not find the non-rising stem gate valves you find on many larger domestic backflow prevention assemblies. The shutoff valves will also be supervised valves, which will either contain tamper switches or be locked in the open position. The NFPA also requires a minimum of a five-second closure time for the valve, so a ball or butterfly valve will have an operator wheel instead of a valve handle for closure. Since a fire system may be under both backpressure and backsiphonage conditions you will not see the use of vacuum breakers of any kind as cross-connection control protection on these systems.
It is important to remember that testing a backflow prevention assembly on a fire system will require additional steps both before and after the test. The system in almost every case will be monitored and alarmed. In a normal test of a backflow assembly on a domestic system we will simply ask for and receive permission to shut the assembly down to conduct the testing. With a fire protection system, you will need to notify the alarm monitoring company — and possibly the fire department — that you will be working on the system. Failure to take this crucial step may result in fire trucks arriving at your test site and significant fines for the unnecessary response. The simple act of closing a large gate valve can also activate a flow switch or may even cause a dry valve to open, so it is important that you either understand the system on which you are working, that you have facility people who understand the system working with you, or that you bring along a fire protection technician to aid you both before and after conducting the backflow assembly testing.
Once the testing is completed and the assembly is returned to the open position, a flow test must be completed to ensure the shutoff valves have opened completely. This may require either a main drain test or a forward flow test. This step is critical to ensure that you have returned this fire protection to service. As someone who has worked in the plumbing and mechanical industry for 46-plus years I have seen gate valves, ball valves and butterfly valves that have failed to open even though the valve stem or valve handle moved back into the open position. That is why the flow test is so important when testing on a fire protection system, which is normally in a no-flow or static condition. On a domestic water system with normal water use a consumer or tester will detect a failed shutoff valve when issues occur doing normal water usage. On a fire protection system this issue may cause a catastrophic failure in the event of an actual fire occurring at the facility.
Some backflow testers think they can avoid any shutoff valve issues by simply never closing either of the backflow assembly’s shutoff valves when performing a field test. They assume the assembly is in a static or no-flow condition and conduct the testing with the assembly shutoff valves in the open position. There are several problems with this approach. The first is that they are modifying the field test procedure. The cornerstones of any testing program are the accurate use of the accepted field test procedure, the certified tester using that field test procedure correctly, and the accuracy of their testing equipment. Think of it like a three-legged stool — if you take one of the legs away the stool falls. The same is true of a testing program where individual testers create their own versions of a field test procedure.
If we conduct a field test on a double-check or a reduced-pressure principle assembly and do not close the number two shutoff how do we ensure the assembly is in a no-flow or static condition? If we use a backpressure test on the second check, are we raising the downstream pressure enough to cause a flow switch to trip, or a dry valve to activate? If we do not follow a valid test procedure, we are not conducting a valid field test. Fire systems can be extremely complicated. Dry valves, deluge systems, fire pumps, antifreeze loops, and the list goes on. If you do not understand how the systems work, your choice is to bring someone with you who does understand the system and can do the required flow testing when you are finished, or don’t field test assemblies of fire protection systems. It really is that simple.
Testing backflow assemblies on at least an annual basis is critical to protecting our water supply. Doing it correctly every time is just as important. Let us do it right, every time.
