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Old April 14th, 2017, 02:41 PM   #1
OkiePC
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1" water valve slow opening and closing

This is for a tank fill application that has a PVC ball valve at present. The operators often open the valve and forget about it, overfilling a tank. We are tasked automating this.

I have it all worked out except for choosing a valve.

The problem is that the 100psi water line is 1" PVC, and subject to severe water hammer during both opening and closing.

I have used the slow closing ASCO red hat valves before, but I think they open quickly. We want it simple and reliable but need to open and close slowly. About ten seconds in each direction would be slow enough if not adjustable.

If I use a motorized ball valve, that is overkill for this on/off operation and then there's the concern about what happens if power is lost.

I have searched quite a bit and found a few potential candidates, but they're all either cheap looking, only speed controlled in one direction, or ridiculously overkill motorized valves with analog control.

I know some of you guys probably can direct me to the exact product I need to locate.

Paul
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Old April 14th, 2017, 03:16 PM   #2
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You could use a solenoid operated "Pump Control Valve" like a Cla-Val. the solenoid operates a small valve that uses line side pressure to force open the main valve slowly. When you want to close it, you cut off the solenoid power, the water drains from behind it and the main valve re-closes, also slowly. They are designed to specifically reduce water hammer. Because it closes by cutting off power to the solenoid, it functions exactly the same when power is lost. http://www.cla-valpacific.com/136-01...alve-p-60.html

You might be able to use your solenoid operated Red Hat style valve with a spring return to closed (for dealing with a power failure), but after that valve, install a hydraulically dampened check valve, also called a "silent check valve". They also are used specifically for the purpose of reducing water hammer. Apco is the one I'm most familiar with.
http://www.dezurik.com/products/prod...lves-csc/8/39/
The thing with that though, I don't know how that would be able to dampen the water hammer on a fast closure of a valve, they usually work in conjunction with a centrifugal pump because the pump slows down, it doesn't immediately stop flow.
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Old April 14th, 2017, 03:30 PM   #3
GaryS
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Check with these guys
I have not used them but from what I see it looks lie they may have something that will work for you


http://www.belimo.eu/CH/EN/index.cfm
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Old April 14th, 2017, 04:06 PM   #4
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Sounds like another example of a customer trying to get controls to mitigate a system design issue. Maybe time to tell them to add a accumulator/suppressor.

GFSignet Motorized Ball valves seem to have actuation times from 10-20sec.
https://www.instrumart.com/assets/EA...-datasheet.pdf

Last edited by GTUnit; April 14th, 2017 at 04:10 PM.
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Old April 14th, 2017, 06:41 PM   #5
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I would use a diaphragm valve. I couldn't give you the brand name, I don't remember, but it is a 0-1A air valve that actuates a diaphragm to allow water to flow. We used these on steam hot water heating systems and had a rate setting on the controllers to limit how fast the water could open and close. These are available with or without feedback (and in your case you wouldn't need feedback).

When you get the low low setpoint, the 0-1A to the air valve is stepped up (we used 4-20mA with a transducer to isolate the load.

It hits max open and and stays there until high point is reached, at which point it steps down.

You could easily do this with a PLC for a controller or get a dedicated controller for the purpose.

I should add, the diaphragm valves are expensive, but everything else is pretty cheap. Drier, regulator, 0-1A air valve and around a hundred bucks for a process controller.

Last edited by sparkie; April 14th, 2017 at 06:44 PM.
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Old April 14th, 2017, 08:01 PM   #6
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Put in a restriction orifice.
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Old April 14th, 2017, 10:03 PM   #7
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Do you have air available? If so, use an air actuated valve. It's super easy to resttict the air for slow open/close.
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Old April 14th, 2017, 10:57 PM   #8
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Thanks for the feedback so far. We don't have air available for this application. It needs to open fully in order to fill the vessel quickly so I don't want to restrict it. The valve fills a mixing chamber to which they add bags of powdered carbon. The operator is not a fan of Cla-val valves due to issues (mainly lack of maintenance) at other locations with big valves.

The principle looks right though, so I may have to check into the cost and sizes. This water line is all 1" PVC that snakes up and over a door with a valve conveniently mounted on the wall near the door handle. Our plan was to install an automated valve just after the hand valve and leave the hand valve open during normal operation, but it could be closed to work on the new valve or in the event of a leak or failure.

I'd like a simple red hat valve that operates slowly both ways which would be simple, reliable, and would close during a power failure. It might be more feasible to go with the slow closing valve and address the fast opening by better securing the piping before and after the thing.
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Old April 15th, 2017, 01:45 AM   #9
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Try these from Burkert. https://www.burkert.co.nz/en/type/6211

Not cheap either unfortunately but I use them on our carry water lines and they cause less hammer that ones which are direct acting. These are servo-assisted so the water pressure behind the valve opens it.

Securing the pipework will be a good idea too.

The other option is a small PRV upstream to help dampen the surge by providing less pressure downstream for the valve to close against.
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Old April 15th, 2017, 06:50 AM   #10
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Motorized on/off with built in battery backed closer if power fails.

http://www.valworx.com/product/elect...epdm-1-24-240v
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Old April 15th, 2017, 07:11 AM   #11
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Asco slow closing solenoid valve

http://www.lesman.com/unleashd/catal...21-spec-R2.pdf
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Old April 15th, 2017, 08:16 AM   #12
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Quote:
Originally Posted by OkiePC View Post
This is for a tank fill application that has a PVC ball valve at present. The operators often open the valve and forget about it, overfilling a tank. We are tasked automating this.

I have it all worked out except for choosing a valve.

The problem is that the 100psi water line is 1" PVC, and subject to severe water hammer during both opening and closing.

I have used the slow closing ASCO red hat valves before, but I think they open quickly. We want it simple and reliable but need to open and close slowly. About ten seconds in each direction would be slow enough if not adjustable.

If I use a motorized ball valve, that is overkill for this on/off operation and then there's the concern about what happens if power is lost.

I have searched quite a bit and found a few potential candidates, but they're all either cheap looking, only speed controlled in one direction, or ridiculously overkill motorized valves with analog control.

I know some of you guys probably can direct me to the exact product I need to locate.

Paul
I have a very similar project coming up in July. Please post the valve you end up choosing and how it worked out.
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Old April 15th, 2017, 10:04 AM   #13
g.mccormick
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Quote:
Originally Posted by g.mccormick View Post
Motorized on/off with built in battery backed closer if power fails.

http://www.valworx.com/product/elect...epdm-1-24-240v
It looks like that valve with the NC failsafe battery backup installed would be about $645. That may seem like a lot, but hours spent researching to find a different valve would eat up money too. That valve that I linked is 10secs for 90deg swing and includes manual override.
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Old April 16th, 2017, 01:02 AM   #14
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http://www.haywardflowcontrol.com/sh...tors-200277--1

I have used these guys with success on a sewage treatment plant.
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Old April 17th, 2017, 09:24 AM   #15
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Has anyone used a "water hammer arrestor" with any success? Such as this randomly selected Google hit:

http://media.wattswater.com/F-WHA.pdf

I was about to buy one for my home until I realized the diaphragm tank from the well pump was not at the correct pressure.
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