Excess pressure pump. The definitive solution where someone in the range of 
AHJ's takes stopping false alarms due to pressure surges. I do mean stopping, 
not reducing. Required in Vancouver (and the rest of B.C.?). Seems New Zealand 
is on the list. 

Can be done without the Gamewell (ADT?) unit. Not required to be listed for 
fire protection service, unless unit also act as the switch for the fire alarm 
system interface. 

Yours, 

Bruce Verhei 

----- Original Message ----- 
From: "Tom Duross" <[email protected]> 
To: [email protected] 
Sent: Sunday, June 28, 2009 7:51:04 AM GMT -08:00 US/Canada Pacific 
Subject: RE: mercoid switch on wet riser 

What Todd said. They probably replaced the original compound type with a 
mercury one. 
>From what I know, Gamewell isn't making them anymore. I think they ceased 
last summer, I drove out to get a diff. switch and they told me. 
Just as an aside, my grandfather is on the patent for this and a few other 
things Gamewell made before and after the depression when they were in 
Newton, MA. I have a beautiful one I "kept" in my basement along with a 
couple of those McCullough type switches I posted about last summer too in 
really nice shape. 
Of course, nothing official but my Dad has a picture of him and the crew 
taken in the shop after another patent was awarded. Funny coincidence. :) 

TD 
Go Red Sox! 

The old Gamewell excess pressure pumps had a very homemade look about them. 
And that sounds like what is being described. Used to be required in Canada 
and parts of Europe don't know if they still are.. 

Richard 


Sounds like an excess pressure pump. These were used in areas with a 
lot of pressure fluctuations to prevent false alarms. This was before 
flow switches with delays. Gamewell was famous for these but 
Firematic made a fairly simple version of the same thing. Some towns 
(at least in this part of the world) required them 



At 11:38 AM 6/27/2009, you wrote: 
>I saw something which I do not understand and hope someone can explain 
>this to me. 
>A 35 year old wet system, manifold with 2 alarm valves. There is a 
>electric flow switch on each riser, I think added recently. 
>The valves were trimmed with the normal motor gongs, etc. 
>The system side gauges are piped together between the two risers, with 
>check valves, a mercoid switch labeled pump switch, and another mecoid 
>switch labeled alarm switch. On this piping there are 3 check valves 
>and a small test cock, presumably for testing. 
>There is a small pump with 1/2 in inlet from supply side of valve 2, 
>which discharges into the pressure gauge piping described above. 
> 
>What is the purpose of this? Was it standard at one time? 
> 

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