Transcript of Coffee Break Training - Sprinkler Main Drain Tests

Coming up on this edition of Coffee Break Training we will discuss Sprinkler Main Drain Tests. So prop your feet up and take five. Coffee Break Training is on next.

Hello everyone and  welcome.  I'm Rob Neale your host for Coffee Break Training. Here at the United States Fire Administration we recognize that fire and building inspectors' busy schedules seldom  allow time to attend lengthy but valuable training and refresher courses. So we have developed  Coffee Break Training, short 5 minute training sessions to provide technical training in fire protection systems, building construction, codes and standards, inspection techniques, hazardous materials, and administrative tips. Now let's get started. 

Today's topic is Sprinkler Main Drain Tests. The main drain test is performed by a competent service technician or fire protection professional to verify the water supply to the sprinkler system is unimpaired and is adequate to supply the sprinkler system.  National Fire Protection  Association Standard 25, Inspection, Testing and Maintenance of Water-Based Fire Protection Systems, recommends main drain tests be conducted at least once each year.  

The main drain is almost always located on the sprinkler riser near the main drain controlling valves.  The main drain is intended to provide drainage for the sprinkler system when it is worked on, but also serves as a critical test point. To conduct the test, the inspector must check the pressure gauges on the fire sprinkler system. On this wet pipe system, the lower gauge is known  as the "supply" gauge, and the  upper guage is the "system" gauge. We will be using the  supply gauge for the test.  

The supply gauge static water pressure should be noted and documented on an appropriate inspection form. Open the main drain valve slowly, and watch what happens to the supply gauge. The pressure on the supply gauge should drop. Once the valve is fully open, allow the water to run until it is clear.  This may take at least two minutes. Note also that the needle on the supply gauge will fluctuate as it  drops. This is a result of turbulence in the main drain pipe.  When the needle stabilizes, note the pressure. This is  known as the full flow pressure.  Document the full flow pressure on a suitable  inspection form so other inspectors can evaluate long-term performance. 

In an upcoming Coffe Break Training podcast, we will show you how to compute the system water volume based on these test results.  

Close the main drain valve slowly to prevent water hammer and stop the water flow.  Sprinkler system water supply valves may be intentionally or accidentally closed, cutting off the water source from the sprinklers. The main drain test is the only reliable method of verifying the water supply is operational. A closed or partially closed valve in the sprinkler supply may prevent the sprinkler system from performing as designed in the event of a fire. The result may be a  catastrophic fire loss.  Problems found during the main drain test should be reported to the  property owner for immediate correction. If the system is inoperable, firefighters in the property's first response district also should be notified.  

For additional information on Sprinkler Main Drain Tests refer to NFPA 25, Standard for the  Inspection Testing and Maintenance of Water-Based Fire Protection Systems. 

Well that's going to do it for this edition of Coffee Break Training. If there is a fire and building inspectors' training related topic you would like us to discuss on Coffee Break, e-mail your suggestions to me, robert.neale@dhs.gov. For your convenience, Coffee Break Training are available for viewing on USFA television and YouTube. You may also download the podcast version, audio only version, or pdf version of Coffee Break Training from the USFA website,  www.usfa.dhs.gov/nfa/coffee-break/index.shtm.

Be safe and join us for the next Coffee Break