Backflow Preventor Testing & Repair

What is Backflow?

Backflow occurs when water flows in the opposite direction of where it is intended to go. In a fire sprinkler system, backflow occurs when water from the fire sprinkler line flows back toward the municipal water source.  

Why are Backflow Preventers Needed?

The job of a backflow preventer is to prevent water in a sprinkler line from flowing back toward the municipal water source. Backflow preventers work to protect water supplies from contamination. Water in fire sprinkler pipes is stagnant and might contain contaminants that could be harmful if consumed. 

Types of Backflow Preventers

There are two common types of backflow preventers for fire protection systems:

• Double Check Valve Assembly – This type of backflow preventer is used in traditional, low-hazard fire protection applications. 

• RPZ Valve Assembly – The RPZ backflow preventer is used in high-hazard applications, such as when chemicals are present. 

Inspections and Testing for Backflow Preventers

Keeping your fire protection system functioning properly requires testing and inspection of backflow prevention devices. Backflow preventer testing should be performed by a certified backflow tester. Testing must be documented and must comply with NFPA and local regulations.  On a weekly or monthly basis, backflow prevention devices should be visually inspected for any signs of damage. Two common types of tests that are performed for backflow preventers include:

• Forward Flow Test – Forward flow tests are performed annually in accordance with NFPA 25 at the designated system flow rate, including hose demand, where hydrants or inside hose stations are located downstream of the backflow preventer. Where a means is not provided at maximum demand, the test shall be conducted at the maximum flow rate possible. This test checks whether the system can get enough water supply in a fire condition.

• Backflow Performance Test – This test checks the performance of your backflow prevention devices to check that the water supply is protected from cross-contamination. This test is performed after the forward flow test in accordance with the requirements of the authority having jurisdiction. 

You should check local or state regulations to learn the frequency and types of backflow prevention testing that is required in your area and for your type of fire protection system.