Dry sprinklers may be kept from failing by undergoing regular testing. For this reason, hiring a qualified fire sprinkler testing business to conduct quarterly and semiannual testing is crucial.
Dry sprinkler systems are installed to prevent fires from becoming catastrophic when temperatures dip below freezing. But routine testing is necessary to provide genuine comfort that such sophisticated technologies will function reliably when it matters most. We continue our article on dry sprinkler systems by looking at the criteria established by the NFPA for testing these systems quarterly and semiannually.
Even the most basic commercial sprinkler system needs periodic testing for optimal operation. As a result of their greater complexity, increased susceptibility to corrosion, and frequent exposure to cold conditions, dry sprinklers require more maintenance to ensure they continue to function correctly.
By using pressured air or nitrogen to seal off the water supply at a dry pipe valve in a warm area, dry sprinkler systems provide effective automatic fire prevention even in subzero conditions. Sprinkler heads release compressed air as heat from a fire trigger them, lowering the pressure and allowing water to flood out of the pipes and onto the blaze.
Scheduled testing of dry sprinkler systems is mandated by the 2017 revision of NFPA 25: Standard for the Inspection, Testing, and Maintenance of Water-Based Fire Protection Systems. If you want accurate results, you need to have competent technicians make thorough physical inspections of your sprinkler system and document their findings in a thorough report that the property owner may keep on hand.
It bears repeating that the NFPA 25 tests discussed in this blog post are standard operating procedures; extra tests may be necessary under exceptional circumstances. When that happens, it’s essential to obtain enough samples from the right places at the correct times using a testing method tailored to the situation. When figuring out what steps to take, it’s a good idea to get in touch with the maker, the listing agency, and the AHJ.
Assuming a starting point, we check the water level.
Priming water improves the seal in some versions of dry pipe valves. At least once every three months, the priming water level should be checked to ensure it is adequate. It’s crucial to keep everything at the right level, as a water column inside the valve would prevent the dry sprinkler system from functioning if allowed to rise too high.
Turn the little priming water level test valve clockwise to check the level of priming water:
If water is flowing steadily, empty it until you hear air escaping.
The water level is acceptable, so you may safely stop the valve if you see any sputtering or mixing of air and water.
Valves should be closed promptly if just air is escaping, which indicates that the water level is too low. Following the manufacturer’s directions, water can be added to the priming cup.
By sounding an alarm before the air pressure decreases to the point when the dry pipe valve opens, and water floods the system, low air pressure alarms prevent unintentional tripping of dry sprinkler systems. If testing procedures are supplied, they are followed to the letter.
If low-air pressure supervisory devices are included with the detection system, they must be checked every three months per the manufacturer’s guidelines.
Dry sprinkler systems are designed so that there is a little lag between the activation of a sprinkler head and the actual release of water onto a fire. Quick-opening devices accelerate the tripping of dry pipe valves, allowing dry sprinkler systems to satisfy NFPA time restrictions for water supply. False trips can occur if they aren’t properly maintained, leading many building owners to disable them.
This is a risky decision since it may delay the water supply for longer than is allowed by NFPA 13, the standard for installing sprinkler systems, allowing the fire to spread beyond the system’s control. The quick-opening mechanism may be inoperable if the gauge pressure atop the device is 0 or much lower than the air pressure in the system.
When water enters the sprinkler pipes via the dry pipe valve, an alarm is triggered either by a mechanical mechanism or an electronic water flow switch. Mechanical Waterflow devices such as water motor gongs must be tested every three months following NFPA 25. In contrast, pressure switch-type Waterflow devices have a more extended testing interval every six months.
Vane-type Waterflow devices are prohibited by the NFPA in dry pipe valves because the force of the water when the valve trips might rip off a vane and shove it into the pipes.
When water leaks through the dry pipe valve into the sprinkler pipes, it can trigger pressure-type Waterflow switches, which send signals to monitoring stations.
Water flow testing aims to verify the functionality of waterflow detection devices and alarms, as well as the transmission and reception of signals to and from the central station if one is in place. You must always alert the fire department and central station before conducting any tests.
Because opening the inspector’s test connection will cause the dry pipe valve to trip, water flow alarm testing for dry sprinklers differs from testing for wet sprinklers. Instead, waterflow alarm testing on a dry pipe valve is started by opening the alarm test line valve.
Regularly, the velocity drip drain, and the water flow test line are the same. If the velocity drip drain is blocked, the dry pipe valve will be tripped when the test water cannot enter the intermediate chamber through a check valve. The velocity drip drain is prone to corrosion buildup that impedes water flow.
Before beginning a water flow test, it is recommended to exercise the velocity drip valve by pressing the plunger several times to ensure that it runs smoothly, there are no obstructions in its path, and that the ball is not stuck in front of the drain hole.
The testing procedure begins with the alarm test valve gradually opening while the velocity drip’s plunger is constantly depressed. If the velocity drip does not produce any water flow after about 60 seconds, the valve is left open, and the water flow test is repeated. After an alarm has been set off, the valve is shut off, and a call is made to a control center to verify that the signal was received. Those conducting the test should notify the relevant authorities (such as fire brigades) when it is complete.
If water flows out of the velocity drip when you open the alarm test valve, you should shut it off immediately. If water cannot reach the intermediate chamber, it is likely because the check valve is not functioning correctly.
- Dry sprinkler systems must be tested twice a year.
- Experiments with a water-flow pressure-switching device
- Unauthorized valve action is signaled via supervisory switches.
For water to reach the sprinkler heads in the event of a fire, the control valves—often referred to informally as butterfly valves (a specific type of valve)—regulate the flow of water in an automated sprinkler system must remain open. One common cause of a malfunctioning sprinkler system is a control valve that has been closed. NFPA 25 mandates semiannual testing of all supervisory valve switches that reveal unlawful control valve use to prevent this from happening.
As part of the testing process, you should verify that the supervisory switches send an electrical signal to the designated monitoring station through an alarm system, detailing any deviations from the valve’s normal operating state.
The safety of a building and its inhabitants depends on the effectiveness of the dry sprinkler system, which can only function if it has been adequately tested. Building owners or their representatives need to verify that the organization or individual they choose to conduct sprinkler testing has the experience and training to carry out the comprehensive tests mandated by NFPA 25.
Need a dry sprinkler system inspection in New Mexico? Dial (505) 889-8999 or fill out this online form to get in touch with Brazas Fire.