[PSUBS-MAILIST] Solenoid valve

Thu Jun 23 08:52:01 EDT 2016

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 need for air, 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 compensate
>for 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
>
>Sent from my iPad
>
>> 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 
>pneumatically
>> operated 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 springs
>> pressure & air pressure in the ballast tanks. when power is on the
>solenoid it
>> draws 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't
>> heat up excessively.
>> The other neoprene gaskets shown are for sealing to the hull.
>> Some sought of gauze needs placing round it to stop foreign matter
>getting
>> in the valve seat.
>> Alan
>> 
>> 
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