Although you might not know it, and you probably do if you use a gas grill, but the tanks that are currently being used today are different than the tanks your parents used.

Finding an older tank, that is still in good working order, might save you some money, but it might not actually work with your grill. Also, older tanks are no longer being filled. There are easy ways to tell if your tank has been updated to the new standards, or if the tank is still a classic model. These upgrades for tanks, required before they can be filled, make the tanks more safe, by preventing them from being overfilled.
What’s Changed
Any tank that was manufactured before September 30, 1998, has the old style valve installed. That’s the way they came from the factory, unless the tank has been retrofitted with a Overfill Prevention Device (OPD). On average, the old cylinders caused about 600 fires every year. It was consistently caused by overfilling.
To help prevent this and to help keep the user safe, the National Fire Prevention Agency told the Consumer Product Safety Commission to include a OPD on each tank. This became effect (and standard practice) April 1st, 2002.
If your tank is not equipped with a OPD, it can’t even be filled. These valves have a plunger inside the tank, and once the tank reaches about 80% filled capacity, the plunger rises and shuts off the flow of propane into the tank. These valves are found on tanks ranging in size from 4 pounds to 40 pounds, most commonly used for gas grills. (The 4 pound bottles are most used as portable tanks for portable grills). Other than the valve, the propane tank design is still the same.
How to Tell
There is an easy way tell if your propane tank has the old style valve on it or not. The first way to tell is y checking the date stamped onto the tank. Each tank, regardless of when it was made, is required to have the manufacturing date stamped onto the tank. You can find this date by looking at the guard surrounding the cylinder valve, also commonly used as a handle.
Tanks have a shelf life of about 12 years, and will need to be recertified as safe after 12 years (recertification lasts for 5 years). If this date is before April 1st, 2002, then your tank could possibly have the old type of valve. If it is manufactured after that date, it should already have one installed. Another easy way to tell is by checking the valve knob. Old valves have a circular, 5 prong knob, while the new valves are designed with a triangular, 3 prong knob.
How to Fix it?
One of the easiest ways to fix the problem is to swap out the tanks with a tank swapping program.
These can be found at most local hardware stores and at some big box stores, and even some gas stations carry propane tanks. They also make conversion kits for propane tanks.
It is highly recommended to let your local propane dealer to change the valve, as well as preform any maintenance or service on your propane tank. These tanks, while generally considered safe, does have the slight possibility of exploding.
Problems with New Tanks
The new valves in the tanks might cause problems with some of the older gas grills, although the new valves are designed to work with the older Pressure Outlet Line (POL).
These new valves also have fittings for the new Marshall Type fittings as well. Make sure to make a leak tight fit on the connections on your grill. The new valves will trigger if a leak proof seal is not made. If the grill works, but has a large amount of yellow flame, takes forever to heat up, or just simply doesn’t work properly, then you will need to adjust the grill. The safety feature in the new valves will restrict the flow of gas if the valve experiences release above certain levels. Usually this happens when the valve is fully opened.
To help prevent this problem, only open the control knob about a fourth of a turn to a half of a turn. This will allow enough gas through to cook properly, without overloading the valve. If you do need to reset the valve, completely turn the tank off, and disconnect the hose and regulator. Give the tank about 5 minutes to reset, and then attach the hoses tightly. Now turn the gas on only about 1/4 – 1/2 a turn.
Leak Test: How to check?
This is the easiest, cheapest way to tell if you have a leak in your gas line or one of your connections. To do so, simply take one part water, and mix in one part dish soap. Then either brush or pour onto the hose and connections (while cold). The soap water mixture will not only make noise if gas is escaping, but will also form bubbles. This will show you where any leaks are, and allow you to fix the problem.
If the leak is at a fitting, try to tighten the fitting. If the fitting still leaks, turn the gas off, un-connect the fitting, and check to see if the rubber washer inside the fitting is in place properly. If it is, remove the rubber fitting and inspect the O-ring. If the O-ring is damaged, dirty, or really old, then replace the O-ring. This should solve the problem. If the leak is coming from a hose, then simply remove the hose, and replace it with a durable parts.
Gas leaks while using a gas grill can be catastrophic, and could lead to death. Leaking gas is never something to ignore. You should check each time you change tanks, and each time you adjust or mess with any of the propane lines. You should also check when setting up your grill for the first time.