Vane type flow switch on fire sprinkler system

[ktxavier]

Everytime we conduct our fire alarm system test, several hours after we leave site, the flow switch trips again. We tested it by opening inspectors test valve and flowing water until alarm system trips. I am with alarm service company and don't know all that much about the particulars of sprinkler systems. Customer states that they have had the sprinkler company look at this and they can't find any issues. Any suggestions?

 

[BigInch]

Perhaps cooling of the fluid and pipes requires additonal flow to repressure. In large firewater systems, jockey pumps are typically provided to supply that extra bit of pressure from time to time.

Only put off until tomorrow what you are willing to die having left undone. - Pablo Picasso

 

[MiketheEngineer]

Leaks??

 

[ktxavier]

No leaks that I am aware of. This only happens once several hours after test. System sits fine for several months until after next test.

 

[BigInch]

What does the test involve?

To quote some old mechanic, "If it ain't broke, don't fix it.", and then bill them for your 4 hour wait time.

Only put off until tomorrow what you are willing to die having left undone. - Pablo Picasso

 

[ktxavier]

The test involves opening the inspectors test valve at the end of the line and flowing water until the flow switch trips.

 

[BigInch]

How much water is required to flow in order to trip the switch? I would think it is an extremely small amount, unless the system is huge or something, and the switch is at the end of the line.

Only put off until tomorrow what you are willing to die having left undone. - Pablo Picasso

 

[gouveia]

Does the system have a relief valve? Does some one manual turn on a pump to pressurize? Just a couple random thoughts.

 

[MiketheEngineer]

Possible air pressure surge??