EPDM Coatings
rvupgradestore.com Composet Products Custom Yacht Interiors

Author Topic: Another propane leak  (Read 375 times)

garyb1st

  • ---
  • Posts: 2125
Another propane leak
« on: October 30, 2017, 02:04:26 PM »
Some of you may recall we replaced the propane regulator on our last trip.  The old unit, which was about a year old, was definitely leaking.  However, we have smelled propane several times since replacing it in August.  This time, and likely before, it's leaking where a large bolt, or plug, threads into the tank.  I was going to replace the propane gauge that snaps onto the plug when I noticed bubbles coming from the 12:00 O'clock position where the plug fits into the tank.  I sprayed with soapy water to make sure.  It's definitely leaking.  The tank is currently 1/4 to 1/2 full.  Is it possible to either tighten the plug or add sealant or do I need to take it to a qualified dealer and let them do the repair. 
Gary B1st

2005 Pace Arrow 35G
2016 Jeep Wrangler

kdbgoat

  • ---
  • Posts: 4125
Re: Another propane leak
« Reply #1 on: October 30, 2017, 02:15:34 PM »
I've never had much luck sealing a leaking fitting while it is under pressure.
I know you believe you understand what you think I said,
But I am not sure you realize what you heard is not what I meant


2016 Leprechaun 319DS

garyb1st

  • ---
  • Posts: 2125
Re: Another propane leak
« Reply #2 on: October 30, 2017, 03:21:15 PM »
I've never had much luck sealing a leaking fitting while it is under pressure.
  I see where that could be a problem.  Wonder if the pressure lessens as the tank empties?  It's about 1/4 full at the moment.  Could turn on the furnace for a few days.  It's getting down to 70 here in L.A.  lol.   
Gary B1st

2005 Pace Arrow 35G
2016 Jeep Wrangler

Utclmjmpr

  • ---
  • Posts: 2993
Re: Another propane leak
« Reply #3 on: October 30, 2017, 03:48:13 PM »
You can use it until its empty,, but be carefull and don't attempt to remove the bolt at any point,,it will fool you.>>>Dan
38' American Tradition 38TT/330 turbo Cummins
Jeep liberty 4 down
72 VW Baja 4 down
Cedar City, Utah
USAF vet. 59-63
The difference between intelligence & stupidity is: intelligence has it's limits
      Albert Einstein.
President Western GM Coach chapter FMCA

Rene T

  • ---
  • Posts: 10026
  • Great being on the right side of the grass
Re: Another propane leak
« Reply #4 on: October 30, 2017, 03:55:30 PM »
If you know what you're doing, and if the RV is outside and far away from any ignition point, I would unplug it (electrically), disconnect the batteries then crack a fitting  somewhere in the line and let it leak out slowly. Like I said, only if you know what you're doing. I know I'll get some grief from this so bring it on.
Rene & Lucille & co-pilot Buddy
AKA  Pep N Mem
2011 Chevy Duramax 2500 HD 4X4
2011 Montana High Country 343RL
From the Granite State of NH
& Florida Snowbird in Lakeland FL

Gary RV_Wizard

  • Forum Staff
  • ---
  • *
  • Posts: 60773
  • RVer Emeritus
Re: Another propane leak
« Reply #5 on: October 30, 2017, 05:10:48 PM »
I'll share your grief, Rene.  ;)   LP in an open (ventilated) area is not particularly dangerous (don't smoke while doing it, though!) and shops and refill stations vent LP into open air all the time.    I would just let the tank bubble away as long as it is outside and not letting gas into the interior of the rig. When the tank is empty, it can be worked on.  Note that an empty tank is just very low pressure - it still has flamable LP vapor inside. In fact, it is very highly combustible when the concentration is low.

Pressure does decrease as the volume goes down, but we are talking a decrease from 300 psi to something less. Not what you would call "low" until it is essentially empty.

Without some idea of what the leaking plug is, though, it's hard to guess how hard or easy it may be to seal. If it's a fitting for mounting a gauge, maybe it can simply be tightened 1/8 turn or so. The risk, of course, is breaking it or damaging to the point where it is impossible to remove & reaplce.
Gary
--------------
Gary Brinck
Summers: Black Mountain, NC
Home: Ocala National Forest, FL

bross

  • ---
  • Posts: 318
Re: Another propane leak
« Reply #6 on: October 30, 2017, 05:30:13 PM »
Tighten it up. If its a pipe plug it's tapered and it will seal as you tighten it. If its a straight thread it a will have a gasket under it that will seal as you put pressure on it. I spent forty years in an oil refinery tightening up on leaks. No big deal
Bill & Doris
Winnebago Adventurer 38Q

garyb1st

  • ---
  • Posts: 2125
Re: Another propane leak
« Reply #7 on: October 30, 2017, 06:12:24 PM »
Thanks for the replies.  I thought about just tightening the plug but was concerned I might actually make it worse.  I need to bring it in for some other work, so I'll have them look at the tank as well.     
Gary B1st

2005 Pace Arrow 35G
2016 Jeep Wrangler

Charlie 5320

  • ---
  • Posts: 1998
Re: Another propane leak
« Reply #8 on: October 30, 2017, 08:29:10 PM »
Thanks for the replies.  I thought about just tightening the plug but was concerned I might actually make it worse.  I need to bring it in for some other work, so I'll have them look at the tank as well.   
If it were mine, I'd burn the propane out and remove the fitting to either inspect or replace it. Use a good quality dope made for use with LP when installing the fitting. You have to make sure the dope is for LP use or it will erode away, maybe that's what happened now. If so it will only get worse.
2003 National Dolphin 5320
496  8.1  Workhorse

98 Damon Daybreak 3130
GM Vortech 454  4L80E
SOLD

Lou Schneider

  • Forum Staff
  • ---
  • *
  • Posts: 7373
Re: Another propane leak
« Reply #9 on: October 30, 2017, 10:37:42 PM »
Pressure does decrease as the volume goes down, but we are talking a decrease from 300 psi to something less. Not what you would call "low" until it is essentially empty.

No, it doesn't.  This is a common misconception that is true for compressed gasses, but propane isn't a compressed gas.  It's a liquid with a very low boiling point that boils into vapor when the temperature is above that. 

A propane tank is a pressure vessel and works like a pressure cooker or a pressurized cooling system in a car.  As the pressure inside the tank increases, the boiling point of the liquid inside it also goes up.  The liquid propane boils until the pressure in the tank raises the boiling point to match the tank temperature.  Then it stops boiling until something reduces the pressure, like drawing off some vapor.

The tank pressure stays constant, as determined by the temperature, until all of the liquid is gone.  That's why you can't use a pressure gauge to tell how much propane is in the tank.

Liquid propane is 270 times as dense as the vapor, so you'll have to vent 270 gallons of vapor for each gallon of liquid propane in the tank.

As far as the tank pressure, it ranges from about 250 PSI at 130 degrees F to 0 PSI at -45 degrees F.  In between it's 24 PSI at 0 degrees, 92 PSI at 60 degrees and 172 PSI at 100 degrees.  The regulator reduces this to about 0.5 PSI (11 inches water column) to feed the appliances.

https://www.propanecarbs.com/propane.html

If you take the tank pressure all the way to zero, you should have the tank purged to remove any air that may have infiltrated into it.  Propane and air is an explosive combination so you only want pure propane in the tank.
« Last Edit: October 31, 2017, 02:29:17 AM by Lou Schneider »

garyb1st

  • ---
  • Posts: 2125
Re: Another propane leak
« Reply #10 on: October 30, 2017, 11:50:55 PM »
Thanks Lou.  Any thoughts on the suggestion that I simply tighten the plug?
Gary B1st

2005 Pace Arrow 35G
2016 Jeep Wrangler

HueyPilotVN

  • ---
  • Posts: 1233
Re: Another propane leak
« Reply #11 on: October 31, 2017, 12:58:14 AM »
There are not too many things that scare me.  However, I am nervous around propane.

Several years ago a good friend of mine that owns a campground in Vermont was filling a propane tank on an older RV.  When she removed the hose connection, the entire tank of propane came shooting out of the tank and created a huge cloud of gas in the campground.

The fire department arrived soon after, but it was very tense until it dissipated and we got the all clear.

I would have a propane dealer purge the tank and have them remove and fix the fitting.  It would not matter to me if it was full.  I just would not mess around with propane under pressure.  It is worth whatever it cost.

It might be a good idea to purge the tank anyway to remove any moisture in it.

By the way, If you wanted to create a huge explosion you could do what the military do and strap an explosive charge on a huge propane tank and drop it out of an aircraft.  If you detonate it above ground it creates a huge blast.  They call it a fuel/air bomb.

Probably should not have related that little fact.  Now someone's wife will worry about the propane tank.  They really are safe and rarely give trouble.









« Last Edit: October 31, 2017, 01:10:39 AM by HueyPilotVN »
Bill Waugh
40' Country Coach DP
34' Stacker Trailer, Trailer Toad
Jeep Commander
Mustang Bracket Race Car
35 years on the road

Lou Schneider

  • Forum Staff
  • ---
  • *
  • Posts: 7373
Re: Another propane leak
« Reply #12 on: October 31, 2017, 01:57:05 AM »
I agree with Bill, let a professional handle it.  I'll attempt to fix a leaking gasoline or diesel tank, worst case you can catch the leaking fuel in another container and deal with it.   The problem with a propane leak is the vapor is heavier than air, so it can run along the ground just like water except you can't see it.  It can pool in a depression, storm sewer, etc. creating a real problem unless there's enough air movement to effectively dissipate it.

The problem with propane vapor pooling at low points is why tunnels with entrances/exits higher than the middle of the tunnel (those that run under rivers, harbors, etc.) are very careful about propane travelling through them, while tunnels through mountains where one or both ends are lower than the middle aren't that concerned.
« Last Edit: October 31, 2017, 02:15:23 AM by Lou Schneider »

garyb1st

  • ---
  • Posts: 2125
Re: Another propane leak
« Reply #13 on: October 31, 2017, 02:12:37 AM »
Thanks Lou.  I'm leaving the wrench in the tool box.   ;)
Gary B1st

2005 Pace Arrow 35G
2016 Jeep Wrangler

ronster

  • ---
  • Posts: 12
Re: Another propane leak
« Reply #14 on: October 31, 2017, 05:32:35 AM »
It can't hurt to tighten it.Most likely a pipe thread,tapered.If you empty tank to reseal,use yellow pipe tape as first choice,its made for gases.White pipe dope dosen't seem to last.Propane is low pressure,seldom over 50 lbs .Good luck.
ronster with nancy,furry kids lucy and ricky riding in a 03 Phaeton 38 Cat power...if it aint a CAT its just a dog!!!

kjansen

  • ---
  • Posts: 1250
Re: Another propane leak
« Reply #15 on: October 31, 2017, 06:56:04 AM »
As a retired pharmacist, I don't work much anymore, but reading this brought to mind a customer I had two weeks ago.

He came to the pharmacy to get a prescription filled with bandages over his head and both hands wrapped.  My first thought was a propane leak and sure enough he told me it was.  He HAD a pickup camper that needed a match to light the stove in order to make his morning coffee.  One match was all it took.  The door was blown 50 feet away and all windows were blown out.  He was very lucky to be alive to tell me about it.

PLEASE install leak detectors in your camper and check for leaks if possible on a regular basis.
Keven Jansen
'06 Chevy 2500 Duramax
'02 Montana Big Sky
Alexandria, Mn

Gary RV_Wizard

  • Forum Staff
  • ---
  • *
  • Posts: 60773
  • RVer Emeritus
Re: Another propane leak
« Reply #16 on: October 31, 2017, 07:15:27 AM »
Quote
The tank pressure stays constant, as determined by the temperature, until all of the liquid is gone.  That's why you can't use a pressure gauge to tell how much propane is in the tank.

Lou is right - there is essentially no drop in tank pressure as long as the tank is reasonably warm so that the vapor boils off continuously. You won't see much difference on a pressure gauge until the tank is nearly empty.
Gary
--------------
Gary Brinck
Summers: Black Mountain, NC
Home: Ocala National Forest, FL

Charlie 5320

  • ---
  • Posts: 1998
Re: Another propane leak
« Reply #17 on: October 31, 2017, 08:13:40 AM »
[ I'm leaving the wrench in the tool box.]


That's the thing to do if you don't feel you can repair it correctly. I have ran 100s of ft of gas pipe in new homes, LP and natural gas.
« Last Edit: October 31, 2017, 08:16:00 AM by Charlie 5320 »
2003 National Dolphin 5320
496  8.1  Workhorse

98 Damon Daybreak 3130
GM Vortech 454  4L80E
SOLD

 

Hosted by Over The Network