If you are a building owner and the building has a sprinkler system, NFPA 25-2011, Standard for the Inspection, Testing, and Maintenance of Water-Based Fire Protection Systems, published by the National Fire Protection Association (NFPA), requires that the main drain of an automatic sprinkler system should be tested at least annually and more often for special conditions. A main drain test is used to identify major reductions in water flow for the system under test.
WHAT IS A MAIN DRAIN?
A Main Drain of an automatic sprinkler system is the control valve. It’s located on your sprinkler riser and it is important to test this once a year to ensure water is flowing correctly and also to clear out any blockages that may arise. The Main Drain is also the point of discharge for all water flowing through the pipes. When a test is performed on the sprinkler system, the Main Drain is opened to release all water before conducting a test or performing any repairs.
HOW DO YOU TEST AND WHY?
There are multiple reasons to test your main drain:
– Repairs
– Restoration
– Adding On/Extending an already existing pipe system
– Keeping up to code or new laws
There are 4 types of drains:
– Wet Systems
– Dry Systems
– Preaction Systems
– Deluge Systems
What to Check For:
– The first thing you want to do is notify the local fire department you will be conducting a test.
– Check your discharge system to make sure it can accurately handle the flow from the sprinkler
– Consistent and stable pressure and water flow
– Your signage for the sprinkler system and Main Drain are accurate and up to code
– There is no debris or blockage in your sprinkler system
– If your piping leads outside that it has accurate protection from the elements
IF ANY OF THE FOLLOWING OCCUR, YOU HAVE FAILED THE SPRINKLER MAIN DRAIN TEST:
Any of the following conditions indicate possible obstructions to the sprinkler water supply that require further
investigation:
– Failure of the static pressure to return to the original reading within a short period of time (i.e., one minute).
– A large drop (i.e., 10%) in the residual pressure as compared to the previous test.
– An extended time required (i.e., more than one minute) for the discharge stream to stabilize during the main drain test.
– A decrease in the static pressure either before or after the main drain test