[PSUBS-MAILIST] Electronic contents gauge

Fri Nov 4 04:53:45 EDT 2016

Hi Alan,
Yes you can clean yourself but the hole is in the order of 3mm diameter and
10mm deep, with crevices at the bottom/diaphragm, so difficult to clean
with certainty. I'm sure there's plenty of people around the world getting
away with less though.

Cheers,
Steve

On 4 Nov 2016 4:46 pm, "Alan via Personal_Submersibles" <
personal_submersibles at psubs.org> wrote:

> Steve,
> could I just clean it myself with isopropyl alcohol.
> I don't know a lot about the sensor construction, but from what I have
> seen
> the orifice directs the medium straight on to the sensor diaphragm.
>  Wouldn't it be a matter of thoroughly cleaning out this hole ( and
> threads ).
> Cheers Alan
>
> Sent from my iPad
>
> On 4/11/2016, at 12:30 pm, Stephen Fordyce via Personal_Submersibles <
> personal_submersibles at psubs.org> wrote:
>
> Hi Alan,
> I think you will find that the silicone (semiconductor type rather than
> rubber-like gasket type) vs ceramic is for the pressure sensing element,
> which sits behind a stainless steel diaphragm, so the process fluid doesn't
> see the silicone or ceramic.
>
> The difficult bit to get the Chinese suppliers to understand is oxygen
> cleaning - and that sort of thing really needs to be cleaned before
> assembly, and during any subsequent testing/calibration process.  Ie. they
> are likely to use water (or maybe even oil - many standard pressure gauges
> are also tested on oil by default) to test, which will leave residue that
> could be very scary in oxygen service.
>
> Cheers,
> Steve
>
> On Thu, Nov 3, 2016 at 9:46 PM, Alan via Personal_Submersibles <
> personal_submersibles at psubs.org> wrote:
>
>> I have had a number of replies from businesses to an enquiry regarding a
>> stainless pressure transmitter that fits a high pressure scuba port.
>> 2 options are diffused silicon (or just silicon) & ceramic.
>> I am wanting to use these on my O2 cylinders as well as air.
>> Does anyone know whether one or the other is better for O2.
>> I am guessing the ceramic is, as silicon may be combustable,
>> but know nothing about this.
>> Regards Alan
>>
>> Sent from my iPad
>>
>> On 3/11/2016, at 5:57 pm, Alan via Personal_Submersibles <
>> personal_submersibles at psubs.org> wrote:
>>
>> Thanks Steve,
>> a really good price but the flow rate to shut looks higher than the full
>> flow rate
>> from my 1st stage hp port.
>> I am now trying to find a pressure transmitter I can pot with 7/16 UNF,
>> about 300bar
>> & stainless 316. Similar to what you suggested but with the compatible
>> thread.
>> Have filled out a buying request on Alibaba with those details. No doubt
>> I will
>> get several offers including a stuffed dog that barks!
>> Cheers Alan
>>
>> Sent from my iPad
>>
>> On 3/11/2016, at 5:23 pm, Stephen Fordyce via Personal_Submersibles <
>> personal_submersibles at psubs.org> wrote:
>>
>> Hi Alan,
>> These also exist and are pretty cheap, although not particularly oxygen
>> friendly:
>> http://valvesandregulators.aquaenvironment.com/item/check-
>> valves-and-flow-limiting-devices/443-flow-fuse/443?&bc=100%7C1009
>>
>> (I stock a couple of these for SCUBA tank filling, but they are not very
>> popular)
>>
>> As you say, I don't think you will be able to use these with a SCUBA reg
>> HP port due to the restricted flow.
>>
>> Cheers,
>> Steve
>>
>>
>> On Thu, Nov 3, 2016 at 7:48 AM, Alan via Personal_Submersibles <
>> personal_submersibles at psubs.org> wrote:
>>
>>> Thanks Hugh,
>>> I just got a price of $160 NZ for a 1/4" 316 excess flow valve.
>>> A lot cheaper than I thought. However looking at the data on their
>>> standard
>>> XS4 series, the "trip" flow on 3000psi is 250 cubic ft per minute or 116
>>> litres
>>> per second. I had measured roughly 2 litres per second coming out of my
>>> 1st stage high pressure port.
>>> They do say they have smaller springs for tripping at a lower flow but it
>>> might be a big step to get to what I want ie. tripping with virtually no
>>> flow.
>>> For me I am leaning toward the option of potting the electronic gauge
>>> that
>>> Steve suggested & having wires through the hull to a plc. plus have
>>> contents
>>> gauges within view of my dome.
>>> Cheers Alan
>>>
>>>
>>> Sent from my iPad
>>>
>>> On 3/11/2016, at 8:34 am, Hugh Fulton via Personal_Submersibles <
>>> personal_submersibles at psubs.org> wrote:
>>>
>>> Hi Hank / Alan,
>>>
>>> There are excess flow valves available for air/gas.  We make them but
>>> also Swagelok have them.  Ours are industrial for high gas flows.
>>>
>>> You need to make sure they are self resetting.  Hugh
>>>
>>>
>>>
>>> *From:* Personal_Submersibles [mailto:personal_submersibles-
>>> bounces at psubs.org <personal_submersibles-bounces at psubs.org>] *On Behalf
>>> Of *hank pronk via Personal_Submersibles
>>> *Sent:* Thursday, 3 November 2016 1:16 AM
>>> *To:* Personal Submersibles General Discussion
>>> *Subject:* Re: [PSUBS-MAILIST] Electronic contents gauge
>>>
>>>
>>>
>>> Alan,
>>>
>>> There is a hydraulic component on cranes etc the allows oil to flow at a
>>> set rate, but if the flow increases dramatically the component becomes a
>>> shut off valve.  This is to protect people and equipment in case a hose or
>>> seal blows out.  maybe there is aa air equivalent?
>>>
>>> Hank
>>>
>>>
>>>
>>> On Wednesday, November 2, 2016 3:43 AM, Alan James via
>>> Personal_Submersibles <personal_submersibles at psubs.org> wrote:
>>>
>>>
>>>
>>> I just experimented with the flow from the high pressure port
>>>
>>> on my 1st stage regulator. That's the one your pressure gauge runs off.
>>>
>>> Even though the hole is literally a pin prick, I was getting at least
>>>
>>> 2 liters a second flow out of it.
>>>
>>> I am building a similar sized sub to Cliff's R300 & a leak like that,
>>>
>>> apart from increasing the pressure massively, would be hazardous
>>>
>>> if it was O2. In 4 minutes I could have 70% O2 based on an air
>>>
>>> volume in the sub of 250 liters.
>>>
>>> I think I'll go for a pressure gauge outside my view port or try potting
>>>
>>> a digital pressure gauge & just send the wires through a penetrator.
>>>
>>> Alan
>>>
>>>
>>> ------------------------------
>>>
>>> *From:* Alan via Personal_Submersibles <personal_submersibles at psubs.org>
>>> *To:* Personal Submersibles General Discussion <
>>> personal_submersibles at psubs.org>
>>> *Sent:* Wednesday, November 2, 2016 12:41 AM
>>> *Subject:* Re: [PSUBS-MAILIST] Electronic contents gauge
>>>
>>>
>>>
>>> Thanks for the advice Steve.
>>>
>>> I haven't looked in to the electronic oxygen add system too deeply.
>>>
>>> Bound to have some questions later on.
>>>
>>> Cheers Alan
>>>
>>>
>>> Sent from my iPad
>>>
>>>
>>> On 1/11/2016, at 9:39 pm, Stephen Fordyce via Personal_Submersibles <
>>> personal_submersibles at psubs.org> wrote:
>>>
>>> Thanks Alan - I should probably point out that my Watchdogs are rather
>>> literally named - ie. they can sense something is wrong and do
>>> something simple about it, but are limited in how complex the reaction can
>>> be.  It can only handle one O2 input, and the control is limited
>>> by controller settings - it's an off-the-shelf item and not fully
>>> programmable like a PLC.  Good for an independent backup or alarm.  As a
>>> primary system it could be made to work but would require a thoughtful
>>> setup.
>>>
>>>
>>>
>>> Eventually I do plan to make a rebreather controller (for the rebreather
>>> I'm designing) which would be perfect (many O2 cell inputs and a solenoid
>>> or two output), but that's a while away!
>>>
>>>
>>>
>>> A key thing to consider in automatic oxygen adding is placement of
>>> sensors, natural mixing of the air and sufficient time delay in the control
>>> system to get meaningful feedback before the next oxygen
>>> injection (Ie. rebreather controllers squirt a little bit of oxygen in,
>>> wait a few seconds for it to mix, and then measure, and squirt in more
>>> accordingly).
>>>
>>>
>>>
>>> Cheers,
>>>
>>> Steve
>>>
>>>
>>>
>>> PS: I also have some M12 plated brass Blue Globe cable glands if you
>>> find yourself short a couple - very hard to get down here.
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>> On Tue, Nov 1, 2016 at 2:19 PM, Alan James via Personal_Submersibles <
>>> personal_submersibles at psubs.org> wrote:
>>>
>>>
>>> Steve,
>>>
>>> sending this again as I didn't receive it...
>>>
>>> Steve,
>>>
>>> I am wanting to build an O2 system like James Cameron had.
>>>
>>> An O2 valve that flows continuously with a top up from a solenoid
>>>
>>> valve which  triggered by a plc that is receiving signals from 3 x O2
>>> sensors.
>>>
>>> Mainly because I want to keep everything as small as possible.
>>>
>>>    With your O2 unit it looks like you could have it doing similar;
>>>
>>> turn on a solenoid to top up the O2 beyond what is flowing in from
>>>
>>> a pre-set valve. A bellows add system that replaces the bellows with
>>>
>>> your "Oxygen Watchdog"
>>>
>>> Know what you mean about UK freight charges, have cancelled items
>>>
>>> because of ridiculous freight charges. Thanks for the offer of buying
>>>
>>> through your firm.
>>>
>>> Cheers Alan
>>>
>>>
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