Propane Tank Response – Case Study (Size-up Sunday)

Response to report of leaking propane cylinder, what do you do?

Leaking Propane Cylinder -

Leaking Propane Cylinder –

This could be a hazmat, single engine, or full assignment response depending on dispatch – you are first in.

  • Park at safe distance, up wind and not becoming an ignition source – check
  • En route fire up gas monitor, if you have one, and make sure it is done in fresh air – check
  • Select proper PPE and consider pulling a line, let’s see what we have – check
  • Size up how big of a cylinder you are dealing with, and whether or not it is in an enclosed environment, anyone down – check

Looks like we are dealing with a fairly static scene compared to a propane tank in this one:

Food Truck involved in multiple vehicle accident - HMN Staff

Food Truck involved in multiple vehicle accident – HMN Staff

Lets get some facts:

It is afternoon and the outside temperature is 104 degrees Fahrenheit.  You arrive at a hardware store and safely park on the side of the structure where you can see the consumer propane storage and the loading dock area.

After contact with the RP you discover a single cylinder used to power their forklift is leaking from one of the ports on the top.  The tank has been removed to a fresh air environment away from ignition sources prior to arrival.  The area is surveyed with a gas monitor and is clear.  There are no ignition sources.

You start to think, PV=nRT, and wow it is hot, the relief valve is doing it’s job, lets put this thing in the shade (in a safe ventilated environment clear from an ignition source) and observe.  Does the Ideal Gas law apply to a cylinder which may have liquid and gas present?  It is hot, any gas portion should expand..makes sense.

Upon further discussion with RP the tank was actually discovered indoors, where the temperature is NOT hot.  The tank was noticed from the smell as well as the hissing sound from a port on the top.  The valve on the top was closed, although noticeably worn.  While the slowly leaking tank rested in the shade in a safe environment we had a few moments to think this out further.

Why not just shoot it?


If I cannot shoot it.  What are the options?

Burn Off?  – This method is done in some jurisdictions and can be a safe option.   Check the link  if below does not play and see how teams in Florida rendered a tank safe with a well done burn off operation.  This option requires the right location, equipment, and regulatory permissions.

Plug? – The leak appeared to be from the relief valve which may just be doing its’ job, and to plug would interfere with that function.  For this to be done safely the plug would also need to have a relief valve.  This was also not an option.  Here is a good reason why not, according to

Relief Valve Problems – A Job for LPG Professionals

Pictured right is a relief valve that was apparently leaking. Instead of calling the propane company to replace the valve, the customer decided to fix the problem himself. Using a soldering iron, he soldered the leak until it stopped leaking. In the process of “repairing” the leak, the customer completely sealed the relief valve in a closed position placing himself and his family in a very dangerous situation.

In this type of situation, a relief valve that is sealed shut will not allow the tank to vent excess pressure if it is overfilled or the pressure inside the tank exceeds the working pressure of the container. In a case where the tank is unable to vent to the outside, the tank is subject to rupturing causing more harm and damage than money saved by trying to fix it yourself. Let the propane company or LPG professional handle any problems with the safety relief valve.


Transfer? – There was no equipment to perform this action.  Not an option.

Let it vent? – How long will this take?  Heck can we just fire up the grill and have a cook out…  We are good now with any ‘plume’ issues but the more time this leaks in this location, the more chance for problems downwind.

Let’s take another look at the cylinder…

Where is it from?  Well there was not an immediate ‘vendor’ to contact as the hardware store received new tanks with their other inventory as they needed the tanks.  They were a busy facility and went through several tanks in a month but they were not from a ‘propane’ vendor.

What about this tank again?  As the ‘active’ facility part had us fooled (all the other cylinders looked pretty new).  Upon further inspection the tank was dated 1987!  With no marking newer (indicating it was never serviced)  this tank was well over the 12 year mark and this valve was likely not working as it was supposed to, it was malfunctioning.  Heck it was due for service last century!

We verified the malfunction by venting the air pressure valve at the top to relieve some extra pressure.  Use the correct PPE, the release can become very cold.  This combined with the cooling measures, should cause a normally functioning relief valve to reset.  Nope.  Old tank, bad valve.

In the meantime the RP contacted a local propane facility (at our suggestion) who was able to roll out and assist.  The field tech was able safely secure and transport the tank to their nearby facility for transfer.  As our options were running out this was much better for everyones safety as well as the business since the tank remained product and not hazardous waste.  It helps that we have a good relationship with local ‘experts’ which in this case was a propane provider.

Stop – Can you identify all of these parts?  Answers below.

Can you identify all of the parts? -

Can you identify all of the parts? –

  • All propane tanks and cylinders must be inspected and re-qualified within 12 years of the date they were manufactured, and again every five, seven or 12 years after the initial re-qualification date.  It is up to the owner of the propane tank to keep track of the tank’s re-qualification date
  • For Propane, at 60 degrees F, the vapor pressure is 92 PSIG, at 100 degrees F the VP is 172 PSIG
  • The auto-ignition temp is much higher than gasoline
  • Take a moment to learn which valve does what – especially when out in your district and see one.

Open your books and take a moment to find out some more propane facts – and visit your local experts!

Now for those parts on the tank – the good stuff to know

Propane cylinder parts - courtesy ToyotaMotors

Propane cylinder parts – courtesy ToyotaMotors

Source -

Source –


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