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Old 19-12-2011, 10:36   #1
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Watermaker - Pressure Regulating Valve

Guys,
Finishing out the watermaker on the boat and the last part required is the pressure regulating valve 0-1000 PSI. What I've found are parts in the $400 to $800 range. Ouch.

Wondering if the part at the link below would work. It's basically a brass pressure regulating valve 0-1000 psi? Cost is $36. I'm sure there is a reason it won;t work just trying to figure out what it is?

TeeJet / Spraying Systems Piston Style Pressure Relief Valve, Brass:: 3/8" NPT, Max 1000 PSI - Dultmeier Sales

Any thoughts greatly appreciated.

Thanks,

Tony
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Old 19-12-2011, 11:29   #2
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Re: Watermaker - Pressure Regulating Valve

Looks like it will work and at $36 dollars worth a shot, can you get flow rate specs for 800psi to see if its enough
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Old 19-12-2011, 13:05   #3
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Re: Watermaker - Pressure Regulating Valve

A CAT 7070 is really the best way to go. I know it's a bit pricey for a pressure valve but there's good reason most major watermaker manufacturers have been using it for a long time. The brass one you linked to just won't hold up to the test of time. For many of the same reasons brass plumbing fittings aren't highly favored on boats. The internals of this valve will quickly foul through corrosion. But it should work for a time. You could buy a lot of them for the $400-$500 price tag of the CAT 7070.
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Old 19-12-2011, 17:58   #4
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If you have a variable pump speed system, such as DC driven or engine driven then you need a back pressure regulating valve like the CAT unit. If you have a fixed speed unit like an AC driven unit then a simple needle valve regulator will be fine.

The bypass valve mentioned will not work without modification as its straight through under normal operation. You could rig it so the normal route is through the bypass outlet hence it would then act as a back pressure regulator.

Dave
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Old 11-01-2012, 13:39   #5
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Re: Watermaker - Pressure Regulating Valve

Ive been using a cheap needle valve made out of brass since 2006. I wonder when it will fail, but so far so good. I've had a DC driven Cat pump and now i have a engine driven pump, but i only make water at anchor and never under way. I do have regulator at the pump output, and a 1000PSI relief valve at the needle valve which is after the pressure vessels.
I would say that flushing with product is what kept my brass needle valve operational for 5 years. If you flush with product after every batch, you should be ok. I am using CAT 290 carwash pump with nickle plated brass manifolds, and its looking pretty good after two years.
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Old 11-11-2015, 21:44   #6
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Re: Watermaker - Pressure Regulating Valve

To revive an old thread...........

I too am facing this economic question and using a genset driven pump so speed is constant. The principle is straight forward enough and I see no reason why a simple needle valve will not work in this application.

Here is a good article explaining why - para K:
Watermaker: Doing It Yourself | | PassageMaker

There are lots of these in SS but he is using a:
400 Series Standard, Hard Seat Needle Valves

Can anyone give me a sound arguement why I need to spend 500 on a General or CAT valve?
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Old 12-11-2015, 00:22   #7
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Re: Watermaker - Pressure Regulating Valve

Found the right needle valve on Ebay and the same one in the Passage maker article. Cv is right for me at 4.2 USG/Min and a 800 psi drop

New and only 30.00 !!!!!!

NOSHOK 404 FFS 1 2 inch FPT 316SS Needle Valve Stainless | eBay

He has 2 more so buy them now
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Old 12-11-2015, 01:24   #8
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Re: Watermaker - Pressure Regulating Valve

Piston pumps of any sort are constant displacement devices so long as they are run at a constant speed. So long as you can adjust the pump speed to be fairly constant a needle valve is fine for pressure adjustment. A pressure relief valve is a prudent precaution on any positive displacement pump system.
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Old 12-11-2015, 01:28   #9
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Re: Watermaker - Pressure Regulating Valve

Quote:
Originally Posted by RaymondR View Post
Piston pumps of any sort are constant displacement devices so long as they are run at a constant speed. So long as you can adjust the pump speed to be fairly constant a needle valve is fine for pressure adjustment. A pressure relief valve is a prudent precaution on any positive displacement pump system.

Agreed
Wonder why pressure reducing type regulators are common in the RO business when the drive is constant?

In any case I bought a needle valve as noted about
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Old 16-11-2015, 21:39   #10
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Re: Watermaker - Pressure Regulating Valve

Have a look at General Pumps stainless relief valve, preset to 950 psi, part number 100993P. It will do the trick and should not cost you an arm and a leg.

Assuming you are in the USA you should be able to get hold of one of these easily, if not let me know.
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Old 16-11-2015, 22:22   #11
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Re: Watermaker - Pressure Regulating Valve

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Originally Posted by H2O on the Go View Post
Have a look at General Pumps stainless relief valve, preset to 950 psi, part number 100993P. It will do the trick and should not cost you an arm and a leg.

Assuming you are in the USA you should be able to get hold of one of these easily, if not let me know.
General Pump website search function leaves a bit to be desired and I could not readily find this. I did however find some General regulators at 550.00

Is this a regulating valve or a pressure relief valve

In this application all that is needed is a simple needle valve
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Old 16-11-2015, 22:29   #12
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Re: Watermaker - Pressure Regulating Valve

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Originally Posted by Hoghead View Post
General Pump website search function leaves a bit to be desired and I could not readily find this. I did however find some General regulators at 550.00

Is this a regulating valve or a pressure relief valve

In this application all that is needed is a simple needle valve
Ok I was thinking pressure relief valve not needle valve, sorry. We have 1/4" BSP Needle valves, SS316 they are rated for 6000psi $150 AUD, plus postage. Let me know if you can't get one at reasonable price over there.



http://www.h2oonthego.com.au/Images/needle_Valve.jpg
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Old 16-11-2015, 22:36   #13
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Re: Watermaker - Pressure Regulating Valve

That is a good price, and even better with your poor dollar, but BSP is very uncommon here and NPT is more widely used.
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Old 16-11-2015, 22:44   #14
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Re: Watermaker - Pressure Regulating Valve

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That is a good price, and even better with your poor dollar, but BSP is very uncommon here and NPT is more widely used.
Yep depends on your country what is most popular NPT is definitely the most widely used in the USA. BSP most popular over here and UK.

Our 12v systems are all NPT and our 110/240v systems are mainly BSP although some NPT.

Can be worked around but need extra parts. Depends on if your using pipe or hose.
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Old 17-11-2015, 06:12   #15
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Re: Watermaker - Pressure Regulating Valve

Why wouldn't a simple needle valve like this work? Dwyer® 3/8" Needle Valve, HNV-SSS33B, Female x Female, Pressures up to 6000 psi: Industrial Needle Valves: Amazon.com: Industrial & Scientific

If you need higher quality, I'm sure Swagelok valves must be only ~$100. They aren't NPT, but they are easy hand swages.

Edit: Oops, I got confused in this thread. I now see the OP needs a regulating valve, and Hoghead already found an inexpensive needle valve.

Mark
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