Watermist Nozzle Testing

Watermist systems are an increasingly popular choice for fire suppression due to their efficient use of water and minimal collateral damage. However, their effectiveness relies heavily on the proper operation of their nozzles, which must be maintained and tested regularly to ensure system performance and compliance with standards.

At ASL, we offer independent, third-party testing of watermist nozzles for a range of applications—including commercial, industrial, residential, and domestic systems.

When Should Nozzles Be Tested?
Testing intervals depend on the system type and applicable standard:

• Industrial and commercial systems should be tested every 3 years (BS 8489-1)
• All other systems should be tested every 5 years (EN 14972-1)

Some nozzle manufacturers and insurers may require more frequent testing.

What We Do

We carry out destructive testing on a sample of watermist heads from your system to assess overall performance. Our comprehensive testing process includes:

• Visual Inspection
  We check for damage, corrosion, loading (e.g. paint or dust), and confirm model details, temperature ratings, and certifications. This helps us identify known issues and select the appropriate test procedures.
• Function Test
  Using a controlled water pressure setup, we confirm that the nozzle activates correctly and allows unimpeded water flow.
• Operating Temperature Test
  Nozzle are gradually heated in a water bath until activation, and the temperature at which they operate is recorded.
• Flow Rate Test
  We measure the flow of water through the nozzle to assess whether it meets performance criteria.

Please note: This is a destructive test—nozzles cannot be returned once tested. A small sample is selected to represent the performance of the wider system.

Sample Selection
Like sprinkler systems, watermist nozzle sampling should be representative of the wider system. We’ll help you determine how many nozzles to submit based on your system type, environment, and usage.