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Old June 22nd, 2018, 09:50 AM   #1
OkiePC
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Vacuum switch compatible with Chlorine Gas

We got a quote from a vendor of some chlorine equipment but it is pretty expensive. ($525) It appears to be a UE brand vacuum switch with an isolator diaphragm. They don't tell us exactly what materials they're suing for this assembly.

I just wanted to see what others have used or would recommend to monitor the presence of vacuum in the line that pulls chlorine gas through a flow regulator. The customer has had an issue in the past with the ejector pump failing to run or other issues that might cause a loss of vacuum and we would wire a contact from a vacuum switch to a PLC input to generate an alarm if it opens. It would be good to have an adjustable switch. I know from experience that chlorine and copper do not get along well, and the same appears to be true for stainless steel.
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Old June 22nd, 2018, 10:38 AM   #2
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Quote:
Originally Posted by OkiePC View Post
We got a quote from a vendor of some chlorine equipment but it is pretty expensive. ($525) It appears to be a UE brand vacuum switch with an isolator diaphragm. They don't tell us exactly what materials they're suing for this assembly.
Hi Paul

I dont think 525 is that bad, any EX or corrosion resistant is not going to be cheap, the body should still be 316 even if it has a isolator built in, I have used Copal in the past and they held up well

http://www.netmotion.com/graphics/ps/pa850.pdf

Your supplier is going to mark everything on these and most of my issues were lead times, we used a company in NC http://www.statesvilleprocess.com/ they made a lot of their own products for temperature and the quality was great... but they also supplied a lot of other brands
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Old June 22nd, 2018, 10:50 AM   #3
OkiePC
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Thanks Mark! The lead time is 5-6 weeks too. The vendor who gave us the quote is a good one of ours, so we may just use them, but I want to weigh other options. After digging deeper, he does spell out more of the details in the price quote, like the UE switch being epoxy coated, and the material in the isolator plus that it is filled with a "halocarbon" fluid. I think that is what drives up the price, plus they probably have to calibrate it after assembly.
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Old June 22nd, 2018, 06:53 PM   #4
Saffa
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My general approach to chlorine gas systems is to install a flow switch on the carry water pump before the gas injector. My experience has been that vacuum regulators rarely fail; it tends to normally be the pump or lack of water. Our systems always have a standby cylinder with auto changeover anyway. I've never monitored vacuum pressure before.

Is there a chlorine residual monitor down stream of the injection point? That's always a good catch all for injection issues.
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Old June 23rd, 2018, 03:47 PM   #5
OkiePC
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Since this is a wastewater application, they do manual tests for chlorine residual downstream, and they should find none since there is also sulfur dioxide injection to eliminate CL2 later in the process.

The original set up did have a vacuum switch, but it had failed (cracked diaphragm) many years ago and we have recently added chlorine flow pacing with electronic analog regulator to the system. They were wasting a lot of chemical running it at a level high enough for peak flow rates...

I thought of monitoring water flow, but there are about two things that could go wrong and cause a lack of chlorine even if water is flowing, but if there is a vacuum, basically the only thing that could go wrong from there is an empty bottle. They do have a mechanical automatic change-over valve on the bottles.

I will probably just go with the $525 switches since the guy who quoted them sells us CL2 equipment and will stand behind his line...I just wanted to see what others might recommend before I spend that much other people'$ money.
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Old June 24th, 2018, 02:31 AM   #6
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Ah, wastewater.

Not something we chlorinate here!
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