[PSUBS-MAILIST] Solenoid valve

Thu Jun 23 19:15:49 EDT 2016

Hank,the iron plunger in my solenoid valves are inside a casing thatthe solenoid fits over, so it is protected. The solenoid valves I have pulled apart all seem to have a smallbi-pass hole that lets air / water in to the back of the valve seat, Ithink I rusted out the spring in one when I got saltwater back up throughmy ballast tank fill line. (will put a one way valve in it). That areain the back of the valve seat seems vulnerable to corrosion & blockage by salt build up. You might be fine in fresh water & myvalves worked in salt water, but I don't think that in salt they will standup in time. You & James have got me started again on the solenoidvalve quest. :)Alan

      From: hank pronk via Personal_Submersibles <personal_submersibles at psubs.org>
 To: Personal Submersibles General Discussion <personal_submersibles at psubs.org> 
 Sent: Friday, June 24, 2016 2:21 AM
 Subject: Re: [PSUBS-MAILIST] Solenoid valve

Alan,I was thinking about electroplating the iron rod to protect it from salt water-then realized that when i took my valve apart to make sure it would work for my application,  it is already plated.  i think a salt water test is in order.  my valve is brass and plated rod, so it may stand up.Hank 

    On Thursday, June 23, 2016 6:52 AM, Sean T. Stevenson via Personal_Submersibles <personal_submersibles at psubs.org> wrote:

 I have solved similar problems by using small solenoid valves to control the application of low pressure air (<100 psi) to the exposed valve, which is air actuated.  This way, all of the electronics are protected from the outside environment, easily repairable / replaceable, and can be observed for correct function. The air signal from the first valve is then what would pass through the hull, so it would have a safety shutoff at the through hull, and then the second (larger) valve is entirely mechanical in nature and made of materials compatible with the environment. I have used several different versions of this, but the solenoid valves I use most often now are Asco Red Hat Next Generation solenoid valves with 24 VDC coils, because they appear to have the least constant power draw when actuated of all the options I've tried.  1/4" is all you nee! d forair, unless you have a particularly huge second valve that requires a fast actuation time. I do something similar with proportional valves too, using an I/P converter (proportional regulator) to convert 4-20 mA control signals to 0-15 psi pilot air pressure which is sent to a large proportional valve which is exposed to a H2S environment.Sean

On June 23, 2016 5:49:13 AM MDT, Alan via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
Hank,I thought of putting bellows around the plunger & oil filling the solenoid,but I would need another set of bellows or something to compensatefor the displaced oil when the plunger retracted.I Googled to try & find a suitable off the shelf valve but couldn't find anything.This design should be fine. It will be corrosion proof  & work at any depth. I am not sure I like the retaining system of the solenoid & might look around for something off the shelf I can adapt.Alan
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On 23/06/2016, at 11:26 pm, hank pronk via Personal_Submersibles <personal_submersibles at psubs.org> wrote:

Alan,Perhaps an oil filled enclosure could be built around the valve.  I have never potted anything on one of these valves, they go strait from the box to the sub (ROV).Hank 

    On Thursday, June 23, 2016 5:18 AM, Alan James via Personal_Submersibles <personal_submersibles at psubs.org> wrote:

  James,I have attached a solenoid valve design based on Vance's  pneumaticallyoperated top hat ballast valve. It was done quickly & is open comment & being evolved.   A solenoid is just a coil of wire with an iron core plunger. As long as the solenoid& plunger are coated with epoxy or similar this simple design should work.The solenoid is clamped in place by the two circular plates & the retaining bolts.(didn't put thread on the bolts) The neoprene gasket seals on it's seat by the springspressure & air pressure in the ballast tanks. when power is on the solenoid itdraws the plunger in to it, which pulls the gasket seal open.A solenoid is easy to make but it may take some experimentation to get the right gauge of wire & number of windings, so that it opens the valve but doesn'theat up excessively.The other neoprene gaskets shown are for sealing to thehull.Some sought of gauze needs placing round it to stop foreign matter gettingin the valve seat. Alan

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