Purging with liquid propane causes the liquid propane in your tank to burst into vapor, freezing the container and condensing any moisture vapor on the tank’s walls, where it will remain while the pressure is blown down. Furthermore, if liquid propane is used to purge, only about half of the air will be eliminated, possibly as little as 25%.
What happens if the propane tank isn’t purged?
- 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.
- After that, you can start filling with propane.
- If the tank isn’t purged, air will be the first gas to escape the propane cylinder, causing your appliance to malfunction.
Why is it necessary to empty a propane tank?
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 explain the phrase before I answer those inquiries “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 freezing point of water 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 (https://goo.gl/jyC57I).
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.
- Only propane vapor is compressed to 15 psi in the container.
- 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.
- This procedure is repeated five times in total.
- 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!
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.
Burping the Propane Tank
To begin, open the hood of your grill to ensure that no gas is accumulating inside. Second, switch off all of the grill’s burners. Make sure that all of the burners are turned off.
Twist the gas tank shutoff valve clockwise until it is completely closed on your propane tank. After that, remove the propane tank hose in the same manner as when you replace the tank. As the excess pressure is released, you’ll probably hear a tiny hiss. Your propane tank just burped like a newborn.
Starting Your Grill Safely
Wait around 30 seconds before reconnecting the hose. The propane regulator will reset itself during this time.
Reconnect the hose once you’ve waited, making sure it’s correctly tightened. Reopen the propane valve a quarter turn once the hose is in place. It’s critical to slowly reopen the valve, as doing so too quickly may cause the regulator to trip again. After you’ve made this initial turn, slowly open it all the way.
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.
Double-Check
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.
How can I get a new propane tank ready?
A basic installation takes only a few hours and can be scheduled in a matter of days, depending on the intricacy, weather, and the availability of our technician or Certified Partner. The materials to install your tank, tank bases/blocks, gas line required to install the tank (up to 10 feet from where the line enters the house), fittings to hook up to the gas line, and travel up to 80 kilometers each way are all included in the basic install package.
To ensure the procedure go as smoothly as possible, our professionals have produced the following preparation checklist.
Prepare your home appliances.
Ensure that all of your propane appliances are properly installed and vented, and that the gas line is connected to an exterior wall. The sole exception is if you live in British Columbia, where you can install the appliances after the tank has been installed, allowing your gas-fitter to perform the final connection while installing your appliances.
Make sure the ground is ready.
Gravel, cement, or a stable ground base should be present where your tank will be installed. Depending on the amount of tank you require, the ground must be level and particular clearances must be adhered to.
For a 420-lb cylinder or vertical-style tankour smallest permanent tank designed for auxiliary heating for water heaters, fireplaces, pools and heatersthe clearance must be 3 ft. away from windows and doors and 10 ft. away from any sources of ignition and air intakes. This tank can be positioned against a structure.
The clearance required for a 500 USWG horizontal-style tank appropriate for residential heating is 10 feet from your home, any building or structure, the property line, windows and doors, and any sources of ignition and air intakes (for example, heat pumps and air conditioners).
How do you know when your propane tank is empty?
We’re in the midst of outdoor living season in Connecticut, which means it’s time to fire up your propane BBQ grill! Simply ensure that you have extra gas for your next summer BBQ.
However, as any veteran propane griller knows, most 20-pound propane barbecue cylinders lack a gauge, which means you’ll need to figure out how much fuel is left in your tank in another method.
Here are three easy ideas to get you started:
1. Make use of warm water. This safe and straightforward method for determining how much propane is left in your tank was given by the FiX IT Home Improvement Channel. To accomplish this,
- Fill a small bucket halfway with warm to hot tap water and set aside.
- Pour the water down the tank’s side.
- Feel for a cool location around the tank’s side using your hand.
The fill level of the tank is at the top of the cold spot (it’s cool because liquid propane inside the tank absorbs heat from the water, making the tank’s metal wall cool to the touch).
2. Check the tank’s weight. On the handle of most propane grill tanks are two numbers: the water capacity (“WC”) and the tare weight (TW), which is the weight of the tank when it is empty. When empty, most grilling tanks weigh around 17 pounds and store around 20 pounds of gas.
Simply weigh your tank on a scale and subtract the TW number to find out how much propane is left in it. If a 27-pound tank has a TW of 17 pounds, there’s about 10 pounds of gas left, or little more than half a tank.
3. Install a gauge on the outside of the building. Options for external propane tank gauges include:
- Installed between the gas line from the grill and the tank’s cut-off valve, inline pressure gauges measure pressures to determine how full the tank is.
- Analog propane scales resemble luggage scales and are pre-programmed to account for your tank’s TW.
- A digital display of remaining cook time and gas fill percentage is provided by digital propane tank scales. Some even have apps for smart phones.
Choose a gauge that you like (they’re available at your local hardware shop and on Amazon) and try it out!
Don’t let your propane cylinder burn you.
Before your next summer party, use these ways to figure out how much gas is left in your tank. Don’t panic if you run out of propane; simply visit one of our Connecticut showrooms for a propane cylinder refill!