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Propane Regulator

11/23/2012 4:58 PM

I am working on a project on an island in the South Pacific that does not have many supplies that we can easily find. We have brought in a company from Europe to do some metal spraying that requires propane at 9.5 bar. All of our regulators only go to 3 bar pressure. Can anyone advise me what, if any, are the issues in changing the tank nipple on an oxygen guage to right hand (propane and oxygen are different handed) and use an oxygen guage on the propane tank?

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#1

Re: Propane Regulator

11/23/2012 5:22 PM

Catastrophic explosion comes to mind.

There's a reason for the backwards threads.

Using them as you suggest might thin out the gene pool.

You may need a pump too.

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#2
In reply to #1

Re: Propane Regulator

11/23/2012 5:47 PM

Lyn: I appreciate your comments and concerns, I have them also, but do you know of any engineering reasons why this cannot be done? This is what I am looking for.

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#3
In reply to #2

Re: Propane Regulator

11/23/2012 5:56 PM

You'll need a pump.

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#4
In reply to #3

Re: Propane Regulator

11/23/2012 7:37 PM

Why a pump? The purpose of a regulator is to reduce pressure from a variable but high pressure on the input side (from the tank) to a steady low pressure on the output side (to the torch or whatever).

I may be missing something, but it seems to me that for the most part, a regulator is a regulator, independent of what gas it's regulating. I know that the basic mechanics -- a needle valve controlled by a spring and diagraphm -- are independent of gas type. Oxygen regulators do need special materials that won't corrode or ignite in a high pressure pure oxygen environment. It would be very dangerous to use a regulator built for propane on an oxygen feed. But I can't see that using an oxygen regulator for propane would be a problem.

Important caveat: I have little experience with tanked gases and regulators, and none of it professional. The fact that I can's *see* that using an oxygen regulator for propane would be dangerous doesnt' mean that it isn't.

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#7
In reply to #4

Re: Propane Regulator

11/23/2012 8:56 PM

Silverthorn, I agree with your analysis that going the other way, propane to oxygen could lead to problems, but I don't see why the direction I want to go - oxygen to propane - would be a problem. I wanted to see if anyone out there could give me good reasons why I couldn't and, so far, no one has.

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#5

Re: Propane Regulator

11/23/2012 8:17 PM

The ambient temperature in the South Pacific may be enough to produce a propane pressure of 9.5 bar. If not, a booster compressor may be needed.

I'm not sure a normal oxygen regulator goes as high as 9.5 bar. There may be corrosion issues with the propane versus materials of construction, but off hand I don't know of any.

If this hookup works, make sure to label prominently the propane tank and any piping leading to the regulator.

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#6

Re: Propane Regulator

11/23/2012 8:17 PM

Before you start playing with a regulator, it is important to know

1. How much propane you will need, say per minute, because this will determine the size of the regulator. If you use too big of a regulator, the hysteresis will be too high.

This will affect your pressure (fluctuations)

If you use a regulator that is too small, the pressure will drop and will not be adequate.

2. What is the supply pressure of your propane gas.

Gases have a typical pressure that is related to the temperature. Your propane gas might not even supply 9.5 bar when you are working in a cold environment.

Here comes increasing the temperature in play or a booster pump (as Lynn figured out).

Propane regulators are about the meanest you can find: rubber membrane, spring (often not even SS) and adjustment bolt. If your oxygen gauge can be adapted, you are good to go - if adjustments are needed, try it out for leaks (e.g. in a bucket of water) and dry it out before use.

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#8
In reply to #6

Re: Propane Regulator

11/23/2012 9:03 PM

Thanks for your comment. Here in the South Pacific it is a balmy 30 deg. C today so cold temperature is not an issue. The propane tanks are stamped 30 bar (450psi) so no problem with the pressure of the tank. I just don't get the comment about the booster pump, especially at 30bar. and I don't think a pump would be needed. Yes, we check all connections for leaks using the tried and true soapy water method. Adaping the oxygen regulator only takes changing the male connection to the tank to a propane thread, very simple.

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#9
In reply to #8

Re: Propane Regulator

11/23/2012 9:07 PM

Good. No booster required.

Never mind.

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#12
In reply to #8

Re: Propane Regulator

11/24/2012 1:17 AM

I had forgotten that the pressure to liquify propane at ambient temperature was so low. Makes me wonder, though, if the equipment that you're trying to accommodate really needs an external regulator at all? It sounds as if it could have its own internal regulator, and 9.5 bar is just the manufacturer's expectation for the approximate unregulated pressure out of the propane tank.

An adapted O2 regulator might not work in this case, simply because the tank side pressure is so much lower than what an O2 regulator is designed for. It wouldn't deliver enough flow.

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#19
In reply to #8

Re: Propane Regulator

11/24/2012 10:08 AM

30 barg is the design pressure of the tank, it's not the actual vapour pressure of the propane. Incidentally in UK the usual design pressure is 17.5 barg (250 psig). At 30°C vapour pressure is about 10 barg. But the temp and pressure will fall in operation, at a rate depending on the size of the tank and the rate of drawoff.

Having said that, I agree with most of the other comments

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#22
In reply to #8

Re: Propane Regulator

11/24/2012 7:59 PM

You have your pressure there. Just install a anti- return valve with flame killer in case you have a backfire.

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#10

Re: Propane Regulator

11/23/2012 11:29 PM

How close to 9.5 bar does your pressure have to be? According to

http://www.engineeringtoolbox.com/propane-vapor-pressure-d_1020.html

the pressure inside your propane tank will be 9.5 bar if you can cool it a little from your 30deg C ambient.

So you will not need a regulator or a pump.

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#11

Re: Propane Regulator

11/24/2012 12:59 AM

a 9.5 bar regulator might be needed as it pertains to the volume of fuel needed rather than the final pressure.. step down regulators will then lower the pressure while maintaining the needed volume.

i would have a long talk with the gentleman that requested a 9.5 bar regulator to make sure there was'nt a mis-communication.

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#13
In reply to #11

Re: Propane Regulator

11/24/2012 1:17 AM

i'll need two one way tickets to tahiti if i'm right.

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#14

Re: Propane Regulator

11/24/2012 1:32 AM

http://www.propane101.com/propaneregulatorfreezing.htm

This link will help you...

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#15

Re: Propane Regulator

11/24/2012 2:41 AM

It may be a silly question, but if this "company from Europe" knew they needed specific regulation of propane supply Why did they not ensure this was available before they came - or brought the required equipment with them??

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#18
In reply to #15

Re: Propane Regulator

11/24/2012 8:07 AM

i'm thinking that they need the regulator at their shop.

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#16

Re: Propane Regulator

11/24/2012 2:50 AM

Yeah, communication with the company would be a good thing. Maybe they don't use regulators, just straight propane out of the bottle at 10 bar/150 psig. Is this their very dangerous way to avoid the expense of an air compressor?

http://aflame.homestead.com/Detonation-Gun-System.html

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#17

Re: Propane Regulator

11/24/2012 4:43 AM

I can't understand why you are getting so involved with someone else's equipment supply problem, with all the potential liability issues involved. It's a perfect recipe for anything from an argument to major legal battles in the event of an incident.

Get the service supplier to sort out his own problems. That is what you are paying him for, or not, as appropriate.

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#20

Re: Propane Regulator

11/24/2012 10:16 AM

As far as using a oxygen regulator on a propane feed source it may or may not work depending on if its an actually universal type HP regulator with the necessary nitrile rubber diaphragm and O rings inside it. If it is it will work just fine as a propane/ NG/ and Hydrogen regulator.

Relating to flow rates I don't think that will be an issue either being oxygen regulators are designed to handle the high CFM flow rates that larger cutting torches require which can often times be supplied from lqiuid oxygen based gas pack units that have output pressures less than 200 PSI peak the flow rates would have to be astronomicaly high to cause freeze up condtions.

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#21

Re: Propane Regulator

11/24/2012 7:45 PM

You might want to consider that the boiling action needed to vaporize large volumes of propane gas from its liquid requires heat from either the surrounding environment or auxiliary heating "vaporization" equipment.

I once witnessed an FAT trial of an industrial furnace shutdown not long after lightoff from lack of supply pressure due the high volume called for because there was insufficient atmoshpheric heating of the propane tank.

Nowhere in the discussion above has the flow rate been mentioned, only pressure.

This does seem to me to be a propane supplier issue, once the pressure/flow rate specs are nailed down.

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#23
In reply to #21

Re: Propane Regulator

11/25/2012 6:59 AM

"Nowhere in the discussion above has the flow rate been mentioned, only pressure" - except in #19

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#24

Re: Propane Regulator

11/25/2012 8:16 AM

There has been lots of cautionary advice provided here from folk plying their trades in parts of the world where compliance paranoia overwhelms their resourceful creativity.

Why the contracting party did or did not bring what appears to be a specialised bit of paraphernalia to complete their mission at a location that would obviously be resource constrained is moot.

The job just needs doing is all.

I find my self improvising solutions fairly regularly here. Modifying parts, fabricating adaptors, creating diabolical marriages....whatever it takes.

I have had to do something fairly similar to what OP is suggesting here more than once. Nothing Youtube worthy occurred.

I don't perform these improvisations lightheartedly and do carefully consider whether the result poses any danger or introduces reliability legacies. The way it's done is as important as how and with what. Internet research plays an important role.

On gas welding apparatus the oxygen and fuel regulators are made from the same materials. Medical oxygen regulators have some different materials, but then they don't regulate to 9.5bar....

My advice to OP is if he is confident that it will solve his problem then he should have a go but to exercise proper working practices to ensure that the solution at least looks right.

Where are you and what are you metal spraying?

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#26
In reply to #24

Re: Propane Regulator

11/25/2012 2:35 PM

You are right in that when you are out in the boonies, ie. away from the expertise of the US, Canada, UK or other 1st world countries we have to improvise. Also, why the contracting company didn't bring the specialized equipment doesn't change the problem; we don't have the right regulators and we have to do the job - that's why they hire people like us. What I want to know is what do we do about it and my best solution is to use oxygen regulators.

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#27
In reply to #26

Re: Propane Regulator

11/25/2012 4:18 PM

As has been pointed out by myself and others, the pressure in your tank is at or very close to the required pressure. So you do not need a regulator.

And the flow will be controlled by whatever device is using the gas. So all you need to worry about is to make sure the device has a flame arrestor which it should have.

Anyway, my experience of tropical islands is that, if it is big enough to require the type of job that you are talking about, there will be an agent for one of the international industrial gas companies and they will have access to expertise and equipment, if you need any, on the next inward flight.

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#28
In reply to #26

Re: Propane Regulator

11/25/2012 6:36 PM

The quickest solution will be for the European company who is doing the work to stick one of their regulators which they use back home in 1st world conditions on a DHL express. Will be there by the end of the week.

If that is what they need, don't mess around.

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#29
In reply to #28

Re: Propane Regulator

11/25/2012 6:56 PM

You are obviously an Aussie: an American would have suggested Fedex, or UPS!

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#30
In reply to #29

Re: Propane Regulator

11/25/2012 7:07 PM

Spot on - and in this part of the world our contractors bring the gear they need, lest they were looking to create a reason to spend time lazing on the beach, spot of deepwater fishing or taking in the sights, whilst waiting for the gear to turn up.

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#31
In reply to #30

Re: Propane Regulator

11/25/2012 9:28 PM

Yeah, but in Australia you can call a supplier and have him send the equipment out right now. We are in New Caledonia, population 230,000, and things just don't happen like that. Our contractor came here without the right equipment, without telling us what they expected us to supply and, to top it all off, their equipment arrived a week later than they did. Unfortunately, this is the real world when you are in remote locations like this.

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#32
In reply to #31

Re: Propane Regulator

11/25/2012 9:57 PM

Unfortunately, this is the real world when you are in remote locations like this.

Yep. Some folk just don't get it.

How are you getting on with that regulator improvisation?

What were those contractors doing for a week? Were they still in a fit state to work?

What are you metal spraying?

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#33
In reply to #32

Re: Propane Regulator

11/25/2012 10:37 PM

We're going to use oxygen regulators but we have to get some shipped in as we need 4 and we don't have any spare ones on site. We will then change the threaded nut to the opposite hand. The contractors are getting things set up and mostly doing SFA - tomorrow we will start the grit blasting and metal spray. We are metal spraying a 500 mm. band around the inside of a 132 MWe CFB boiler.

Thanks all for your comments, much appreciated.

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#25

Re: Propane Regulator

11/25/2012 9:06 AM

LPG cylinders are extensively used with oxygen for cutting/welding. They are fitted with pressure regulators (like in oxygen cylinders). The properties like vapor pressure at ambient temp is nearly similar to propane. Pressure regulators of LPG can also be used for propane if required pressure is similar. Regulator of oxygen should not be used for propane. The best thing would be to contact your propane manufacturer/supplier for correct advise.

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#34

Re: Propane Regulator

12/20/2012 12:32 PM

I think the European company may have been saying that your propane supply must stay above 28 degrees centigrade (which coresponds to a pressure of about 9.5 bar gauge). If you are consuming much (CFM) from a tank which is too small it will get colder (and loose pressure). You may have to heat the tank. Suggest steam to avoid fire hazzard.

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