How Much Does It Cost To Purge A Propane Tank?

Getting your tank purged by a professional will, for the most part, be inexpensive. Many establishments will only charge you for the petrol you put in the tank throughout the purging procedure. However, on top of the expense of your fuel, a purge would often cost $3 to $5. You don’t have to be concerned about this because it is only a small labor price.

If you reside in a location where propane tanks are not common, the cost of a purge may be greater. For a medium-sized tank, some places may charge as much as $10 to $15.

What does having a propane tank purged imply?

It may be necessary to purge the propane container if one or more of a motorhome’s gas-burning appliances display weird, unpredictable, or difficult-to-diagnose problems. Before being filled for the first time, brand-new propane containers must be properly purged. So, what exactly is purging? Does this rule apply to all RV propane tanks? How can you tell if your container need this type of service? And who is capable of doing it?

I’ll define the term before I answer those questions “A container for propane.” Most RVs come with horizontal propane tanks that are bolted to the coach’s frame. The American Society of Mechanical Engineers (ASME) regulates typical RV propane canisters in its Boiler and Pressure Vessel Code. A tank is an ASME horizontal container. An ASME tank’s capacity is commonly given in gallons.

Some older motorhomes and smaller Sort C coaches may have upright propane containers installed in a side compartment; this is the same type of container found on towable RVs and home gas barbecue grills. Cylinders are such containers (which can be vertical or horizontal) that are regulated by the US Department of Transportation (DOT) under the Hazardous Materials Regulations. Transport Canada regulates cylinders bound for Canadian provinces (TC). A DOT/TC cylinder’s capacity is usually expressed in liquid pounds.

As a result, an ASME tank is permanently attached to the coach, whereas a DOT cylinder is portable and changeable. At some point, both sorts of containers must be emptied.

Requalification examinations are not required for ASME tanks, although they are required for DOT cylinders. DOT cylinders used to require a 12-year requalification examination following the date of manufacturing, which is stamped on the cylinder’s collar. However, a new rule went into force on January 23, 2017. The initial requalification time is cut in half, from 12 to 10 years from the date of production. When the more sophisticated volumetric expansion testing process is used, the rule reduces the term from 12 to 10 years. Following a proof pressure test, the requalification time for DOT cylinders is increased from seven to ten years. After the initial requalification testing, DOT cylinders must be visually inspected every five years.

Before being shipped, new propane containers are hydrostatically tested for leaks. When a container for an RV, whether it’s a tank or a cylinder, is brought from the supplier, it’s normally filled with compressed air (or sometimes another inert gas). Moisture and other pollutants can be found in the air. Purging eliminates air, moisture, and pollutants; if the purge procedure is not completed before the container is filled with propane for the first time, combustion issues or pressure anomalies in the supply line may arise later.

Unfortunately, because a new motorhome is typically supplied to the owner with a full (or almost full) propane container, most new motorhome buyers have no idea whether their propane container was properly purged prior to that initial filling. That is a question I recommend asking during the walk-through or before taking delivery. For verification, request to see the predelivery inspection (PDI) form. In reality, the selling dealer shall provide a copy of the signed PDI checkoff sheet to every new motorhome buyer. It’s considerably more difficult to resolve a future problem linked to a contaminated container without it. Before taking retail delivery of an RV, it’s in both the dealer’s and the buyer’s best interests to have a proper purge certified in writing.

Purging is also applicable to older propane containers. In reality, any time a container is opened to the atmosphere for any reason, it must be purified again before being refilled with new fuel. Let’s say the internal float assembly or shut-off valve malfunctions and needs to be replaced; the tank will need to be purged after the replacement because air has been allowed to enter. Moisture and maybe other pollutants are present in that air.

Even a small amount of water at the bottom of a propane cylinder might cause issues. The presence of moisture from the container to the pressure regulator’s inlet can cause the regulator to freeze. Regulator freeze-up can take two forms, both of which have deleterious consequences.

The fuel in the container vaporizes on its pressured trip to the regulator inlet, causing one sort of regulator freeze-up. Individual portions of the pressure regulator lower variable container pressure in two phases to the supply line pressure required by the appliances. In order for the pressure to be dropped consecutively and gradually, propane vapor must travel through small orifices in these two stages. Propane is a kind of gas “The temperature at which water boils is minus 44 degrees Fahrenheit. It exists in liquid form below that and vaporizes above that. As a result, any remaining water will freeze in those small interior orifices, preventing propane vapor from flowing through the regulator.

The second form of regulator freeze-up occurs when mud, water, or slush splashes up from the pavement during the winter months, freezes, and plugs the regulator’s second-stage atmospheric vent hole. If the regulator’s diaphragm can’t breathe, it can’t regulate, and it will just lock up. That’s why, while operation, the vent section must be positioned downward and the regulator must be covered at all times. For a thorough visual explanation, see the FMCA’s Motorhome House Calls video (

If either type of regulator freezes, there will be no propane flow, and the appliances will shut down as if the container were empty. Remember that propane is stored and delivered in the container as a liquid, but it is consumed as a vapor at the appliances. Also, moisture in the container can lower the Btu/gallon coefficient, requiring more propane gas to provide the same amount of heat at the burners.

The following are some of the other issues linked with moisture in the propane container:

  • There’s a chance of rust forming. Rust can grow larger pockets as a result of persistent moisture exposure, which could lead to a breach in the container wall.
  • The propane’s odorant’s effectiveness has been reduced. Propane is odorless and colorless by nature, thus between distillation and delivery to the supplier, ethyl mercaptan is added. A propane leak is indicated by the odor of ethyl mercaptan. However, moisture in the container causes the mercaptan odor to decrease to the point where it may be undetectable.

Failure to properly purge a new container might potentially cause a problem. When trying to fill a container with propane after it has been filled with shipping air, you risk creating excessive internal pressure. This may cause the pressure relief valve to open, allowing fuel to escape. The pressure relief valve is a part of the service valve on a DOT cylinder. It is a separate fitting that is placed into an ASME tank.

If more than one appliance is having problems, a container that has been in use for a while may need to be purged. For example, the furnace may not start immediately; the water heater burner may splutter; the cooktop burner flame may lift off the burner; or a burner flame may be unusually huge or small, or more orange than blue in color. Any device that isn’t working properly is a cause for concern and should be investigated. It could simply be a dirty appliance or an out-of-adjustment regulator, but it could also be caused by moisture inside the container.

To correctly purge a propane container, licensed and master certified RV service personnel are taught. When looking for an aftermarket treatment, make sure to double-check with the service department that the purging will be done by a trained person. Alternatively, most propane retailers may perform the service.

As previously stated, new tanks and cylinders are normally filled with air before being sent, while containers already in use will be filled with propane. In the case of the latter, the leftover propane in the container must be removed or burned up before purging. Schedule a purging service when a container is nearly empty to avoid a costly waste of fuel. However, in some instances, the fuel can be caught and reused.

Even though propane is held as a liquid in the container, purging is only done using propane vapor. The purge begins in a secure, controlled environment away from heat and spark-generating equipment. Although only fully qualified RV service technicians or propane retailer employees should undertake these processes, motorhome owners should be aware of them. The following are the details:

  • The pressure in the container should be 0 psi. When a fresh container is filled with air, the air is simply released into the atmosphere via the service valve or the set maximum liquid level gauge valve (also called the 20 percent valve).
  • If there is any moisture in the tank, it is emptied through the service valve (only DOT/TC cylinders). If necessary, a drying agent for ASME tanks can be added to the tank.
  • The propane vapor is released at 15 psi by opening the service valve or the 20 percent fixed maximum liquid level valve. Note that certain specialised purge equipment comes with a specific vapor return tube that prevents the vapor from being released into the atmosphere.
  • The pressure is alleviated or released after the container is re-pressurized to 15 psi.
  • The 15 psi of propane vapor is kept in the container after the sixth pressurization. After that, all fittings, valves, and container attachments are leak checked.

The container can then be safely filled to its normal 80 percent capacity with liquid propane. The remaining 20% is set out for vapor extraction and expansion. Before entering the pressure regulator, liquid propane boils and vaporizes at the top of the container. Liquid propane overfilling is dangerous and can cause regulator and appliance failure. Thankfully, protections are built into all new propane canisters to assist stop the flow of incoming liquid propane during the filling process.

Because safety is so important, I recommend having a trained RV service technician test the pressure regulator, as well as the entire propane gas distribution system, once a year. Examine the container’s condition. In addition, the propane leak detector should be tested on a regular basis by the coach owner.

If the odorant from the propane is detected, turn off the container’s service valve immediately and schedule the coach for testing. Because the approach permits propane to vent directly to the atmosphere, the stench of the mercaptan may linger a bit longer than usual during the purging process and subsequent refilling of the propane container.

If you’re looking for a new motorhome, make sure to inquire about the propane purging process on the new tank. Existing coach owners should get their propane systems inspected every year and keep a close eye on how well their appliances are working. Remember that RVing is more than a pastime; it’s a way of life!

Is it necessary to purge propane tanks?

New tanks may include water, air, or other impurities, according to national safety requirements, and they must be eliminated before filling the container for the first time and putting it into use. For this first time purging service, do not take your new tank to a gas station or a typical RV dealer.

Is it possible to purge a propane tank in a reasonable amount of time?

Allow the propane vapors to bleed out of your new propane tank by turning the connecting line valve on the used tank to the “purge” position. It will take less than a minute to complete this task.

What happens if you don’t empty your gas tank?

  • Before being filled with propane for the first time, all new propane tanks must be purged of air and moisture.
  • A small amount of propane vapor gas is injected into the tank and subsequently expelled during the purging procedure, which must be done by a skilled propane service technician. This procedure is repeated three to four times. This is not something you should try on your own. Always get your tank purged by a skilled specialist.
  • Because propane is heavier than air, it will drive air out of the propane tank during the vapor’s evacuation.
  • If the tank isn’t purged, air will be the first gas to escape the propane cylinder, causing your appliance to malfunction.

What is the best way to purge a propane tank before cutting it?

Cleaning a propane tank properly before welding and cutting is necessary to meet the job’s safety standards. It just only a few easy preventative measures, which are outlined below:

Disconnect the Tank

Close the valve after removing any hose attachments. The gas may or may not escape once you disconnect the hose, depending on the valve attachment. For increased safety, the most recent tanks have a plunger that keeps the gas from leaking. If your tank didn’t come with a plunger, put on your gloves first before disconnecting the attachments, especially if you’re working with a full tank.

Take the Tank Out into Open Space

If there is a lot of gas in the tank, move it to an open area away from trees and people before you open the valve. Propane is poisonous to plants and can damage trees if it comes into touch with them. To guarantee that the gas dissipates as it is released, find a clearing or open-air site with plenty of airflow.

Tilt the Tank Sideways

Tilt the tank to the side where the valve opens as an extra precaution. It will be easier to get the gas out if you do so. This will also ensure that the majority of the gas from the tank escapes.


Connect the tank to your grill and open the valve to double-check for any leftovers. Then attempt to light the grill. The fire will consume any residual gas. We recommend that you should not omit this step because any trace of the combustible chemical left behind can be fatal and is a recipe for disaster.

Shut the Valve

Even after all of the propane has been removed from the tank, the stench that remains is harmful. The predominant fragrance can catch fire if you start welding with the valve open, and the tank might blow up in your face as you weld.

Cut the Top Off

The decision to remove the top depends on the container’s intended function, although in most circumstances, the head must be removed. During the cutting operation, be sure you don’t cut the tank open before removing the valve. Simply remove the handles from the tank’s head once the valve has been closed.

Check for Gas Once Again

Reopen the plug, depress the plunger, and listen for any leftover gas. It’s all about being meticulous and repeating the steps while cleaning a gas tank for welding. Welding or cutting open a tank that has been inadequately emptied might be fatal.

Leave it Inverted Overnight

Place the piece you removed from the top on a table or in the flow. Remove the tank from the cutout and place it on top of it. Invert the cylinder overnight, making sure that the tank’s opening is not covered.

Wash the Tank

Fill the cylinder halfway with water, then add a small amount of liquid soap. Shake it vigorously to incorporate the soap and water, then rinse it completely. Fill it up with water at least twice when rinsing to ensure you get all of the soap out.

If you don’t have time to leave the tank open overnight, repeat the process twice or three times for further safety. It is vital to wash it out because it removes all remnants of the gas as well as its odor.

The procedure for emptying out a propane tank is lengthy, but because propane is a highly volatile material, it is vital for the welder’s safety that it be followed to the letter. It’s critical to leave it inverted overnight and wash it out to ensure that all of the gas is gone and the tank is ready for welding.

Use Dry Ice

Many people also propose simply disconnecting the valve and filling the tank with dry ice to eliminate all traces of propane. While this is effective, you should still rinse the tank at least once to remove any remains that have stuck to the sides, or leave the tank out in the open for a few days.

What does it mean to be pre-purged?

Pre-purge is the process of exhausting unburned gas in a combustion chamber before the exhauster ignites it, preventing a gas explosion. Prior to ignition, a pre-purge is performed. It’s known as Post-Purge to forcefully exhaust after turning off the burner.

Why isn’t my fully charged propane tank working?

Here’s a list of troubleshooting steps to take if your barbecue tank isn’t working:

  • Double-check that the hose attachment is securely attached to the propane tank, and that the screw-on valve is securely fastened. Some propane tanks contain safety measures that prevent gas from escaping from the canister unless the hose connection to the gas release mechanism is tightly locked.
  • Take a look at the connector you’re using. It won’t be long enough to depress the check valve inside the valve if it’s less than an inch long. You’ll need a new connector that’s over an inch long in this scenario.
  • The tank may not release propane if the valve is turned all the way on. This is a precautionary measure. Restart the process by turning the valve only once before lighting the grill.
  • Continue adjusting the valve in small increments to increase the flame until it reaches the desired height.
  • If none of these steps work, you may have a malfunctioning regulator that prevents propane from flowing. It’s preferable to acquire a new hose with a regulator and try again in this scenario.

If your propane grill tank is still giving you problems despite the fact that the connectors and valves appear to be in good working order, you may need to replace it.