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(am still trying to get the pictures into this post!! I have had this problem before, can anybody send me an idiots guide?)
This weekend we lost our gas pressure. I thought that the tank was empty, and switched to the bottle. This worked for 10 minutes, then fizzled out. Cracking the bottle connection there was plenty of pressure there, but nothing was getting through the regulator. This was a Truma secumotion item actually made by Gok.
Its a known problem, the plasticisers from the hose cause waxes to secrete out and block the regulators - or is it?
Before continuing I would just like you to know that I am a chartered engineer and I work for a company that design flow meters and pressure regulators!
I had also read that it could be washed out with hot water, but there was no way I could get anything in there.
I went and bought a Gaslow regulator as I was not going to buy the same again, after reading how soon they die.
I then cut the Truma one open on the lathe.
Picture 1 shows the waxy deposit. Not hard at all, infact about as fluid as margarine on a warm day. Nothing that the 150 psi from the bottle would have a problem moving. It also looks exactly the same as the coating we find on pipeline equipment removed from gas lines (where there is no rubber pipe).
Picture 2 shows a screwdriver where the blade is about the same width as the eye on the diaphram.
picture 3 shows the screwdriver inserted where the eye would be. This closes the valve off and nothing will flow through it. Without the screwdriver I can blow through the valve. Note the angle of the operating arm and the meniscuss of "wax" (more like oil! at the end of the screwdriver).
Picture 4 shows the valve seat with a clear hole through it. No wax deposit here.
Picture 5 shows the swollen rubber on the arm of the valve. It is sticky and has obviously adsorbed the oil.
Picture 6 shows the rubber trimmed back to flush. Note the black marks on the paper from the break down of the rubber.
Picture 7 shows the installed arm, and prestow its is horizontal with plenty of movement to open.
It should be noted that Propane is a hyrdrocarbon and has been seperated out from crude oil. A certain amount of carryover would be expected, however the "wet" propane is passed through an absorbtion oil to remove traces of gasoline, and passes quality control if it has less that 0.05ml of contaminants per litre. These contaminants are likely to be various sizes of hydrocarbon chain molecules (some might be oil) along with the absorbtion oil.
In the last year we have used 275 litres of gas, so the permitted contaminant is about 10cc. I doubt if there is 10 micro cc in there!
Anybody designing regulators for the gas industry must know about these contaminants and if they have looked at any regulators or valve gear returned from gas lines then they will find oily deposits. They will also know that the rubber used should be "high Nitrile" for this type of service.
Conclusion: The rubber is incompatable with the permitted contaminants in the gas and has swollen.
Conclusion: The product has a design fault and is not fit for purpose.
Excuse: Plastisers have leached from the pipe. Rubbish, besides if they had then the pipe is not made of the correct material.
Excuse: The waxy deposits have blocked the valve. Rubbish, the incompatable rubber has blocked the valve.
The long and short of it... If Truma cant fint the right rubber in 5 years of rejects... do not buy their regulators. If you buy a new motorhome, ask for a non-Truma regulator to be fitted.
This happened just two months after purchased from new. We had it changed under warranty by Truma at Derby. However it was replaced by a bog standard Truma regulator, none of the securimotion models being in stock!
Having paid extra for the extra facility we were rather annoyed, but we have not had any trouble with the basic regulator in 5 years.
Thanks Oilslick. I would love to see the photos, click >here< to see the how to include photos.
peedee
______________________________________________________________ The best journeys are not always in straight lines
For an account of our journeys click >here< (Last updated 1st March 2012)
An excellent post by oilslick, thanks very much. Looking forward to seeing the photos. We replaced our failed Truma with a Clesse as used by Gaslow and I have yet to hear of a failure.
I do believe that many materials are not exactly what they are specified as and are extremely difficult to quality test. The same thing seems to happen with stainless steels used in the Marine Industry the old parts never corroded in salt water but now the same parts from the same supplier go rusty almost like mild steel.
I have followed this saga for a few years and it has also been suggested that it is oil carryover from refillable autogas bottles as well as leachate from hoses. Do the dispensing pumps have lubrication systems as it wouldn't be so critical for cars running on liquid gas?
We have had no problems with our secumotion regulator in two years (big mistake mentioning this ). We use a stainless steel hose from the Gaslow bottle and a genuine Truma rubber hose from the backup Calor propane bottle.
I also worked as a design/development engineer in the regulator and hydraulics industry for many years and have always thought that the Truma problem may have been a material compatability problem with the rubber ( a generic word).
We often saw failed devices with swollen and degraded polymer components and the selection of the best compatible material was critical.
There can also be a quality control problem as even High nitrile etc compounds could vary. I have visited a rubber seal manufacturer where the mixes are made like ingredients for a cake
I'm sure Truma engineers must have seen this rubber material failure when they used to supply replacements FOC but I see that now they are selling an inline filter for about Ģ80 !! as a fix (not a solution).
We carry a spare Clesse regulator for when the Truma one fails.
Steve
______________________________________________________________ Steve & Sheila
Read about our 2011 tour to Spain and Portugal
at
www.motorhomeandaway.com
Thanks for the reminder about this. I meant to buy a spare regulator before our last trip, but didn't.
When we were fitting our Gaslow conversion, I'd read about the problems on here with the rubber hoses, so ordered the stainless steel versions. But a spare regulator would be a good idea anyway.
Mine failed after 13 months just over a week ago, dealer told me 12 month warranty (incorrect as it turned out) tried phoning Truma got nowhere, emailed them and after 3 days no reply.
Rather miffed I went onto their Facebook site and posted a polite complaint asking why they don't reply to customers.
That stung I had a reply within hours, they phoned me back first thing Monday, Regulator warrantied 2 years but not covered if due to waxy/oily deposits, explained mine had leaked from small yellow drilled plug on left hand side. Asked to send it to their service dept (no freepost offer) if its leakage they will replace it as its a safety issue otherwise not their problem.
As we were touring at the time replaced it with a Gaslow Regulator.
Truma need to get their act together.
Will update when I hear from them.
______________________________________________________________ The point is that´s not the Point!
It's really good that somebody who clearly knows what he's talking about has been able to determine exactly why Truma regulators are unfit for purpose. Like so many others, I had one fail after a year or so. Replaced it with the cheapest non-Truma reg, didn't do anything else, no repositioning or hose replacement, and four years later I've still had no problems.
I did contact Truma at the time and they were in total denial - and clearly still are. It's scandalous.
Just to add, I missed this out of my article... I can catagorically tell you it is not the hose. We havent got a hose between our tank and regulator, it is a copper pipe.
Will try and post the pictures now... (but how do I add more than one picture??)
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