View Full Version : propane clearances

John Arnold
05-11-2007, 11:41 AM
I rarely see propane which is why I'm posting this photo. I know clearances have been discussed recently and I'm going to revisit those posts, but I'd be interested in any comments.
The big goose neck pvc pipe is a fresh air return intake, not combustion air. The small pvc pipe at the lower left is the furnace exhaust. All three windows are openable.

Jerry Peck
05-11-2007, 01:08 PM
Whoa, that basement (or crawl space) could become full of leaking propane!

Among other things I see.

John Arnold
05-11-2007, 03:36 PM
Thanks, Jerry
(obvious attempt on my part to put this back in the New Posts section without using "bump").
Aside from proximity to openable windows, and air intakes (and exhausts), I'm thinking the radon equipment could be source of ignition.

Scott Patterson
05-11-2007, 03:46 PM
This might help.
I would say 10' from the Radon mitigation fan. 5' from the crawl space entrance.

John Arnold
05-11-2007, 05:13 PM
Thanks Scott. I had already saved that illustration from a previous thread, plus CodeCheck has one.

Bob Harper
05-11-2007, 05:44 PM
NFPA 58"Cylinders alongside of buildings shall be located and installed so that the discharge from the cylinder pressure relief device is at least 3 ft horizontally away from any building opening that is below the level of such discharge. The discharge from cylinder pressure relief devices shall be located not less than 5ft. in any direction away from any exterior source of ignition, openings into direct vent (sealed combustion sysytems) appliances, or mechanical ventilation air intakes."

There is a lot more in "58 you need to consider above the three sketches like the one Scott showed, which, BTW is one for ASME containers. If these are ASME containers, it would apply; if DOT cylinders, then the first diagram inappendix I would apply. Most of the spacing rules require you to determine whether ASME vs. DOT, combined water capacity, and whether filled on site or not.

I zoomed in on those tanks and their support is inadequate in my opinion. One good Nor'easter and those tanks could roll down the hill. It would most likely break the high pressure pigtail btw tanks but could also leak out of the pressure relief (shouldn't but could). Have you ever seen liquid phase propane issuing out of a tank? It expands 270x. If it leaks from the high pressure pigtail, you could have a 150psi flame thrower. That would surely make it onto Youtube.

Note the vent line on that second stage regulator to the left of the window. See the two copper tubes? One comes out of the vent and runs back to the tank bonnet most likely. That is how they can put that reg. next to the window. Too bad the cylinders are too close to the openings and ignition source. Also note, those are two different size and make tanks. From the looks of things, the larger tank was added on as was some of that exterior piping.

John, I would reocommend those tanks be re-set on more stable ground away from the building. Maybe they could install a buried ASME tank away from trouble.

One major hazard I see is the lack of a shutoff at that second stage regulator. Code required in case of rupture, the gas can be shut off right there. That is no time to be fiddling with the tanks. Shut it off at the regulator first then at the tanks then call the propane supplier.

John Arnold
05-11-2007, 05:51 PM
Bob - Thanks much. I already wrote up the poor support. I'll add the bit about a shut-off at that regulator.

John Arnold
05-12-2007, 04:43 AM
Bob - Here's a detail shot of that regulator. There are two shut-off valves, one of the left, one on the right. Should there be other ones?

Bob Harper
05-12-2007, 06:26 AM
Yes, those are downstream of the regulator. The gas enters from the copper line emerging from the ground and that's where there should be a shutoff.

Those shutoffs to appliances might actually comply with the IFGC if they were to meet 3 criteria:
1) be "readily accessible", which these are. You can walk up and operate them without step ladders, tools, remove panels, etc.
2) serve only that appliance. Anything else downstream of those shutoffs except one appliance each?
3) be lableled. If they put tags on them denoting to which appliance they shut off that would actually count.

While we're at it, that copper should have been sleeved in PVC or conduit, esp. where it penetrates the masonry wall.


JD Johnson
09-04-2008, 01:27 PM
I found this thread while searching for information about tank clearances. The clearances referenced in the diagram appear to apply to tanks that are filled on site. I have an application, where a gas log fireplace is fueled by a 20 gallon portable LP tank, located on the exterior of the home. The portable LP tank is about 5' from the A/C coil.

So my question is, can someone clarify if the clearances shown on the diagram posted in this thread apply to portable LP containers, or is there is a clearance requirement for portable LP containers?

Thanks much - Stay safe

Bob Harper
09-04-2008, 02:23 PM
JD, there are three diagrams in Appendix I of NFPA 58 showing tank clearances. First, you have DOT "cylinders", which is what a 20 lb. tank is. Then you have one for aboveground ASME "containers" and one for belowground "containers". The tank markings will tell you if it is ASME rated. You can have DOT cylinders that are filled on site or portable.

A 20lb BBQ-type cylinder is waaay undersized for a gas log set and is hazardous. Being a DOt cylinder, it can be 5 ft. away from the compressor or other sources of ignition if other criteria are met such as the ignition source not being downhill from the regulator. Also, residential applications other than portable BBQ's must have two stage regulation.


JD Johnson
09-04-2008, 02:32 PM
Thanks Bob, I could not find those appendix online, so I appreciate your assistance.

Rick Hurst
05-14-2009, 08:30 PM
LP regulator next to Condensing unit.

Whats the rule?


Bob Harper
05-15-2009, 05:37 AM
Rick, depending upon whether this is a DOT 'cylinder' or ASME 'container', the clearance is either 3' or 10 ft. from a source of ignition. Both the condenser and it's service disconnect are 'sources of ignition', so it is a problem. They can correct it by simply running a vent line back to the tank.

Jerry Peck
05-15-2009, 07:11 AM
Rick, depending upon whether this is a DOT 'cylinder' or ASME 'container', the clearance is either 3' or 10 ft. from a source of ignition.


In that photo (the photo Rick posted, not the original posts photos), where there is no cylinder, just a regulator with its vent, and which could be from an underground tank or from metered natural gas, I though the clearance with either 3' or 5' (cannot remember which).

Presuming there is no "tank", the clearance from the regulator vent is ... ?

Rick Hurst
05-15-2009, 07:19 AM
Someone passed this on to me. Thought I would post it here.

"I know this one!!!!! I got my gas certification last year.

The Two code books that we use in Vermont (and most other states) is NFPA 54 and NFPA 56. One covers everything outside of the building and the other covers everything inside of the building. I believe your situation is covered by both if you have to look it up.

But that being said. The quick answer is 10 ft. from the condensing unit. HOWEVER you can make your situation legal by runing a vent pipe that will terminate 10 feet from the unit. The vent pipe must pitch away from the regulator so that no water can freeze in it and block the pipe. The vent pipe can be PVC.

It is possible that pressure could build up and the vent will pop on that regulator. If the condensing unit calls and the contactor arcs a fire could result if the gas is within 10 ft of the unit." end of quote

I thought I had heard the 10ft. before but was sure.

Bob Harper
05-15-2009, 06:18 PM
Ok, here it is out of a 2001 edition of NFPA 58: "The point of discharge from the required pressure relief device on regulating equipment installed outside of buildings in fixed piping systems shall be located not less than 3 ft horizontally away from any building opening below the level of such discharge, and not beneath any building unless this space is well ventilated to the outside and is no enclosed more than 50 percent of its perimeter. The point of discharge shall also be located not less than 5ft. in any direction away from any source of ignition, openings into direct vent (sealed combustion system) appliances, or mechanical ventilation air intakes. Where a vent line is used to comply with the point of discharge requirements, it shall comply with and (c)."

The other 3ft versus 10 foot clearances for DOT cylinders versus ASME containers has to do with the point of transfer and exposures (fill cap). Therefore, such clearances are not to the edge of the tank but the fill cap inside the bonnet.


Rob Turner
05-19-2009, 09:22 PM
In Texas this would be a definate no no. ASME tanks must be 10 ft min. from the building, property line or source of ignition.
As for Dot Cylinders, 3ft minimum. You have to take 10ft if it's possible to get.

Rick Hurst
05-20-2009, 07:29 AM
Here's another problem one from yesterday.