[PSUBS-MAILIST] Electronic contents gauge

Sun Nov 6 03:47:25 EST 2016

Hi Alan, plenty of different philosophies out there on what's acceptable
for oxygen service and cleaning - my position is probably quite
conservative, based on industry and SCUBA standards/requirements.

Thanks for the offer of some samples but I'm happy with my current
arrangements.

Cheers,
Steve

On 4 Nov 2016 8:26 pm, "Alan via Personal_Submersibles" <
personal_submersibles at psubs.org> wrote:

> Thanks Steve,
> yes, and a small fire in the high pressure port probably wouldn't be fatal
> :)
> I would think that it would be hard to start a fire with the inrush
> through that
> small hp port pin hole even if there was a fuel source.
>  I have about 12 quotes, 1 as low as US$37- . I think it was on a quantity
> of 5.
> I am now asking them if they are able to be O2 cleaned with alcohol.
> If you are interested I could send you some of the quotes or buy a few
> extra for
> you.
> Cheers Alan
>
> Sent from my iPad
>
> On 4/11/2016, at 9:53 pm, Stephen Fordyce via Personal_Submersibles <
> personal_submersibles at psubs.org> wrote:
>
> 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-va
>>> lves-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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