isolation valve on pressure switch

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inspector Dave
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Joined: Tue Jan 08, 2019 5:20

isolation valve on pressure switch

Post by inspector Dave » Tue Jan 08, 2019 3:23

Hi there, I am new to this so excuse me if i don't have the accurate lingo/terms.
On a recent installation of a residential sprinkler system (pumps from a storage tank) there is an isolation valve before the pressure switch.
If this valve were inadvertently closed, I believe the system would not detect the pressure drop, no pump start or flow switch activated, thus no alarm not to mention the location burning down.
Is this a code violation (Ontario) or just not best practice?
As the system has supervisory on the input/output valves to the pump, it did not make sense that a valve would be allowed in this position.
photo attached

I was going to remove the handle as a precaution.

Your thoughts please.

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Location: Vancouver, B. C., Canada

Re: isolation valve on pressure switch

Post by FIRETEK » Wed Jan 09, 2019 10:34

This is unusual. The switch that starts the pump is definitely installed in the wrong location. The valve illustrated just ahead of the gauge is actually there to enable you to turn off the water to the gauge so you can change it out without having to drain the whole system first. This is a fairly easy fix (to do it the right way). Move the valve to the gauge side of the "T" so there is no isolation between the pressure switch and the system. You WILL have to drain the system if you ever have to change out the pressure switch though. I am curious though. If a pressure drop starts the pump, what's the gauge pressure to turn it back off again? I'm concerned that if there isn't a significant difference, then the pump is liable to start cycling on and off. Wouldn't a wet valve with a jockey pump work better here (i.e. in a setup similar to a high-rise fire pump installation)?
Frank Kurz
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