LPG system question

The device is the pressure regulator. It has been damaged by sulfur compounds in your LPG. Contact your supplier and have them replace it. DO NOT attempt cleaning or repair, get a new one.

I agree.

Do Not Try To Repair.

You could be putting your life or someone elses in jeopardy if you mess with it. Please get a new one.

In the center of the adjuster there might be a reset pin. It will look like the head of a nail. You can grab this with a pair of long nose pliers and pull out on it until you feel it click. I cannot tell from the angle of your picture if the pin is there.

Most of the regulators I have worked with are set up that if the gas is turned off or gas pressure is lost before the regulator this pin will drop in shutting down the regulator. It then has to be reset as described above.

Very important. . . Do not adjust the threaded adjuster in the regulator. If you have turned it, it must be adjusted with a special pressure gauge to the proper pressure. Close is not good enough!!! Too high or too low could cause an explosion.

Keith, Vulcan, Drew:

Thanks for your reponses and I can appreciate the necessary cautions. By sulfur in the propane, I'm guessing you might be referring to the odorant added in trace amounts? To signal when gas is escaping and not burning? I'm also guessing that by "damage by the medium" is meant sulfurous degradation of (perhaps crystallization on) a resilient diaphragm..or something like that? I believe there are good reason to believe that this--sulfur damage or any other kind of valve fault--should not be the case:

1. Seems to me that such a failure would be more likely to "precipitate" at very low ambient temperature; and the current lows here are at around 60F+/-...and 30+ minimum year-round.
2. Odorant concentration would be at highest as the storage tank approaches empty; but my tank has never approached empty, or very much exceeded half empty (over 100 gallons to refill) for as long as I can remember...probably 8 years or more.
3. Such damage to the point of total failure would seem to be a very long time in coming. However, the valve you see here is not more than 3 years--maybe only 2 winters--since installation brand new. It replaced one of the larger, "heavy," silver-gray looking (I'm guessing: magnesium) valves...the kind so familiar to household, natural gas consumers down there in Texas. That valve had been in service for probably 50 years or more...and it was replaced not because it tested bad, but only becaue of its age; and because the installer could find no other source of an occasional, faint smell of propane near the storage tank--the kind of minute leakage that could simply have been normal "relief" venting in our very hot summers here(?).

As I write this, Drew, I am dial-up downloading from the Rego link that you provided. Perhaps the catalog will point me towards a field service manual...and an "offical" safe procedure for restoring valve operability.

Pebbles:

I sense that the advise you provided might be very close to what I was looking for. I had tried to post pics showing all aspects of the overall valve (on the left) as well as views straight in (lower right) and an oblique view (upper left) showing what looks to me like pressure compensation spring and adjustment threads. I was also anticipating that someone might be able to explain the function of the "nipple" that extends from the black cover cap. It appears to extend through the adjuster towards the "nail head" at the center inside the valve. Whether it has a function related to regulation, relief, resetting, or something else I can't tell just from looking...

Your description of a "nail head" aptly describes what I recall seeing at the center...maybe you can see the small, light colored dot at the center in the pic? But, I'm going to see if I can find and post a clearer (and bigger) straight-in view for you to look at...just to be on the safe side. As to using needle nose pliers, I'm not so sure if there would be clearance enough through the small round opening in the adjuster that engages the internal threads. Maybe I'll need to look for a thinner pliers than what I already have; or maybe a special tool will be required. I'll need to look in to that....

Also, your description of what causes a valve to need "resetting" very aptly describes what happened in this case. The valve had, indeed, been temporarily disconnected from propane at the main shut-off valve when that valve was disconnected from the outfeed line to the regulator.

Another thing... as to resetting the regulator, unless you or someone says otherwise, I will assume that this must be done only during inactive state, with propane flow cut off competely at the main cut-off valve.

As to the threaded spring-pressure adjuster, this has not been moved by me; and there is not good reason to believe it has been changed at all by anyone else. I observed when the valve was newly installed that no adjustment was made, so it should still be at its factory presetting and correctly adjusted for my propane system. But, just in case, I would take due precaution--including having someone standing at the main shutoff valve--to prevent any explosion...when very cautiously opening--and prepared to quickly shut--any "consumer" valve that the propane feeds in to.

One final thing...

Just how "open" would you say that the feeder line to the valve must be in order to initiate a "regulator shut down"? Are we talking total loss of propane pressure--and exposure to the atmosphere? Or could a simple, minutely slow leak that persisted for, say, a few days be enough to trigger the regulator to shut down? Or simply closing the main shutoff and opening it back up?

Again, thanks to everyone for your kind assistance.

I'm sorry man, that is not the pin I was looking for. It is looking like the regulator has gone bad. Surely the propane company has someone that could check it out for no charge.

Hi,

Could you confirm the model number of the valve that is shown in your photos? It looks like an LV4403 of some kind. If it is, then the 'nipple' you describe in the Cover Cap is a travel limiter to stop excess movement of the diaphragm. The 'Nail head' that you can see is the end of the central spindle of the Diaphragm assembly, it is this that butts up against the limit stop.

This type of valve, unlike globe valves, cannot shut itself fully during operation, even with the downstream stop valve shut, so it is unlikely to be jammed tight shut due to being inactive but with the inlet pressure still applied. The only way to shut it tight is to apply pressure the 'wrong' way round i.e. through the outlet port (you haven't connected it backwards have you?)

You might try a little gentle pressure on the 'nail head' to try to push it 'into' the valve body, if the valve were stuck shut then this might ease it open again.

As to resetting the valve; this valve should remain in the fully open position when no pressure is applied to it (assuming of course that the loading spring is adjusted to the correct outlet pressure) so no resetting is necessary.

I've just had a thought; Can you make some reasonably accurate measurements and determine the distance between the end of the 'nail head' and the end of the nipple when the cap is screwed in place on the regulator body? If this value is zero, or very little, then the valve is probably jammed shut and needs releasing. If the value is much greater - I'm guessing at about 1/2" to 3/4" - then the valve is probably open and the blockage is due to another source.

One other thing; as the photos are oriented, which is the inlet to your regulator? If it is the bottom of the picture, then it may be that a foreign body has found it's way into the chamber of the regulator and could be fouling the valve crank mechanism, holding it in the closed position.

These are all that come to mind at the moment, it is difficult to diagnose a fault like this without dismantling the regulator, but I hope this is of some help.

Drew

You are pretty close. It is an LV404…series—the LV404896 dual stage, to be exact. I had figured as much about the cover cap…and here is a casing-cut-away illustration of the valve assembly I found using the link you provided. It clearly shows the cap projection in a position to stop further movement of the "diaphragm" (if, indeed, that is what it is), and, of a hinged linkage (I think this is what you refer to as a crank) which, in turn, (apparently) restricts/regulates flow of gas into the regulator. [Text continues below pic.]

To answer first your last question, the regulator inlet is at the top; and the bottom is about 3 feet above the ground…from which the "riser" pipe from the house service line extends up from underground. Now, about your suggestions….which all seem very sensible to me now that I've seen the cutaway showing the inner construction… But, it appears I will not need to try them…because the regulator has (as it were) self corrected and fuel is now flowing to the house. This restoration of flow happened (was first discovered) in a most peculiar way that you might find amusing. As we prepared breakfast this (one) morning, I had occasion to place a dish on the gas range, at which time I noticed that the area above the range was overly warm—as if heat had been venting upward from the oven cavity.. In answer to my question, I was told that the oven had been found ON at warm setting—and a broiler flame had been observed. A check inside the oven confirmed that it, too, was unexpectedly warm. I asked and my wife replied that she had tried the range-top burners to no avail; my attempt achieved the same result. Then I tried the oven regulator…yes, a flame. Top burner again…nothing! "How could this be?" I wondered aloud, knowing that the main fuel valve was cut off at the tank! And even if gas was somehow bypassing that valve, what about the regulator…? Out at the tank, I found the main gas valve not closed (as I had left it for safety's sake) but opened! It then occurred to me that perhaps it was the fuel company which, without any contact, and without leaving any note, had come by unnoticed…come by because I had attempted to summon their aid as suggested by pebbles #7 above. Unobserved, and expecting to fix a potential regulator lockup, I surmised, they had instead discovered the main valve to be shut off, had concluded that their dumb customer was confused…, and had simply opened the main valve and left. (They would also discover, I later [kinda] found out, that the tank was full and in no need of refill. So maybe it was the customer service phone rep in a faraway sate—to be exact, in the "Show Me" ['cuz telling me's not enough] state who had confused—or caused to be confused—a repair service order for a fill-up service order!?) But, discovering the open main valve, and the regulator seemingly (now) regulating, still did not answer the questions, "Why?" …why the regulator, if not locked up, had seemed to be locked up? …and why, with fuel now flowing, only the oven burner can produce a flame?

So just for fun—and now that we seem to have "fixed" the main regulator—anyone want to venture a guess: what is going on with the system now? Why one burner lights when other burners, which would light, won't light.

And now that we're getting near solving the mystery, I would also like to understand the main regulator function a bit better. Looking again at the picture, since it is a cutaway and not a section rendering I cannot identify how/where and in which directions gas flows between chambers or into the regulator outlet port. I've added annotations to the drawing which might be part of the answer. Your clarification the functional aspect and how the illustration shows it will also be appreciated.

PS: This response was delayed because server kept rejecting the pic, saying problem with MIME, etc. So I changed the pic from .tiff to .jpg and it finally worked. Thanks for waiting.

Hi,

I can't offer any suggestions on your oven's bizarre behaviour, not my field I'm afraid. I can try to explain the operation of the Pressure Regulator though.

You state that it is a two stage Regulator and the number you quote agrees with that but the diagram shows only a single stage. Not to worry, the illustration is very similar to the second stage so starting there:

In its rest state, with no gas flowing, the Regulator Valve is wide open. This occurs because the Load Spring (B) presses down on the Diaphragm which, through the crank linkage, holds the Valve open. When gas is introduced into the Regulator through the inlet, with the outlet stop valve closed, the pressure in the Valve Body rises. As it rises, the pressure acts on the diaphragm producing a force that opposes the Load Spring. Eventually the Diaphragm will rise sufficiently to close the Regulator Valve. This is the Set Pressure of the Regulator and can be monitored on a down-stream pressure gauge. When the outlet stop valve is opened, the pressure in the Valve Body starts to drop as the demand increases. As the pressure drops, the Diaphragm starts to descend thereby opening the Regulator Valve to compensate. With a steady demand on the Regulator the Diaphragm/Valve mechanism will find a steady state.

The Pressure Regulator in your illustration has an extra feature; in the centre of the Diaphragm is a Relief Valve. This valve is held closed by the smaller concentric spring inside the Load Spring. If the pressure in the Valve Body should rise due to an abnormality downstream it would normally (in a valve of this type) force the Regulator Valve more firmly closed. With a Relief Valve fitted, this dangerous situation is avoided because the centre of the diaphragm will simply lift off at a pre-determined over-pressure and the gas will vent out of the Spring Housing.

I can't make out the internals of the first stage Regulator Valve, but it looks to be a very compact device.

I came across this article in my wanderings, I wondered if you were aware of it?

http://www.nrw.qld.gov.au/mines/petroleum/pdf/safety_alert029.pdf

By the 'Show me' state did you mean Missouri? I vaguely recall a line from the film 'Outlaw Jose Wales' that implied that.

I hope that this is of some help.

Drew