sgvaibhav said:

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I have a domestic LPG cylinder.

Composition - 20% Propane and 80% Butane.
Temperature - Around 30-35 deg C.

I wanted to know the temperature of the gas inside the cylinder or in other words, if i take gas out directly from the cylinder without using pressure reducing regulator, what will be the pressure of this gas?

The database I have shows the saturation pressure for 100% propane (C3H8) would be 150 psig at 90 F (32.5 C). For 100% butane (C4H10) it gives 48 psig at 90 F. For a mixture of 20% propane and 80% butane it gives 57 psig at 90 F. That's saturation pressure of course.

Hey Danger. The oxygen you have in your cylinders is pure gas, but LPG isn't. It's basically a boiling liquid with the vapor in equilibrium above the liquid kinda like the coolant in your car when it overheats. As soon as you pop the cap off your radiator, you get a snootfull of boiling liquid because it's right on the verge of boiling. When you remove the radiator cap, it starts boiling vigorously because the pressure in your radiator suddenly goes down. Same thing with the LPG. When you start removing some of the gas, the pressure in the tank drops and some of the liquid boils off and creates vapor. When it does, it cools slightly because some of the energy in the liquid goes into boiling and converting the small amount of liquid to gas. Of course, once it cools off a bit, heat from the environment gets in and warms it back up. But in the case of your oxygen cylinders, there's nothing but gas inside, so there's no boiling and the pressure is determined only by how much oxygen is in your cylinder.

The database I have shows the saturation pressure for 100% propane (C) would be 150 psig at 90 F (32.5 C). For 100% butane (C) it gives 48 psig at 90 F. For a mixture of 20% propane and 80% butane it gives 57 psig at 90 F. That's saturation pressure of course.Hey Danger. The oxygen you have in your cylinders is pure gas, but LPG isn't. It's basically a boiling liquid with the vapor in equilibrium above the liquid kinda like the coolant in your car when it overheats. As soon as you pop the cap off your radiator, you get a snootfull of boiling liquid because it's right on the verge of boiling. When you remove the radiator cap, it starts boiling vigorously because the pressure in your radiator suddenly goes down. Same thing with the LPG. When you start removing some of the gas, the pressure in the tank drops and some of the liquid boils off and creates vapor. When it does, it cools slightly because some of the energy in the liquid goes into boiling and converting the small amount of liquid to gas. Of course, once it cools off a bit, heat from the environment gets in and warms it back up. But in the case of your oxygen cylinders, there's nothing but gas inside, so there's no boiling and the pressure is determined only by how much oxygen is in your cylinder.

Propane regulator facts, propane facts, propane 101, high pressure and low pressure, types of propane regulators, and 

a word about propane tanks

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Outdoor gas appliances may access low pressure propane gas through a gas convenience outlet located somewhere after the low pressure regulator or directly from a portable tank like the kind you see at Home Depot or Lowes. Portable tanks require propane pressure regulation. Sometimes a low pressure regulator is built directly into the gas appliance, but more often is installed on the portable tank itself. Check with your gas appliance manufacturer to see what propane pressure is required for your appliance.

Pressure in a propane tank, large or small, can range between 100 and 200 psi...or even higher when the tank gets hot in the sun. This propane tank pressure must be reduced and be regulated for use in a home, motor home, camper, or an outdoor gas appliance. A residential application will require a low pressure regulator which reduces the gas pressure to 6 ounces (10.5 inches water column).This low pressure regulator will be located on or near the main supply tank to the home, motor home, or camper.Outdoor gas appliances may access low pressure propane gas through a gas convenience outlet located somewhere after the low pressure regulator or directly from a portable tank like the kind you see at Home Depot or Lowes. Portable tanks require propane pressure regulation. Sometimes a low pressure regulator is built directly into the gas appliance, but more often is installed on the portable tank itself. Check with your gas appliance manufacturer to see what propane pressure is required for your appliance.

 

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 That is, the propane pressure is fixed at a certain pressure; i.e., 10 psi or 20 psi. Attenuation of the amount of gas delivered to the appliance is done by use of an inline ball valve or needle control valve located either on the hose or built into the appliance.

The other common type of high pressure regulator is an "adjustable" high pressure regulator

Outdoor gas appliances such as high heat cast iron burners require the use of a high pressure regulator because they need more volumes of gas than a low pressure regulator can deliver. High pressure regulators regulate the output pressure from 1 psi to as high as 60 psi. There are a number of different high pressure regulators available. Some high pressure regulators are "preset" That is, the propane pressure is fixed at a certain pressure; i.e., 10 psi or 20 psi. Attenuation of the amount of gas delivered to the appliance is done by use of an inline ball valve or needle control valve located either on the hose or built into the appliance.The other common type of high pressure regulator is an . Adjustable high pressure regulators are available in 0-20 psi, 0-30 psi, and 0-60 psi versions and have an output pressure adjustment control built directly into the regulator.

 

Should I buy the highest pressure propane regulator to insure enough gas delivery?

There is no advantage of having a propane regulator with a lot more btu/hr output than you actually need.  

Depending on the number of btu/hr that the gas appliance(s) requires, one chooses the adjustable propane gas regulator which delivers the required number of btu/hr. Choose the propane regulator that is the closest match.  

As you choose a higher and higher pressure high pressure propane regulator, the degree of control that the propane regulator valve has over the gas output decreases; i.e., turning the valve an 1/8" in a 0-60 psi adjustable propane regulator has a lot more effect than turning the valve an 1/8" in a 0-20 psi adjustable propane regulator. Choose the high pressure regulator which most closely matches your actual btu/hr need.

 

How long will my portable tank of propane last?

  

This is easy to figure out if you know the number of pounds of gas that is in your full tank and the btu/hr demand of your burner or other gas appliance. One pound of liquid gas in your tank has 21,591 btu/hr fuel value. The most common tank is a 20 pound tank (also sometimes referred to as a 5 gallon tank). This is the kind of portable tank you would find at a Home Depot, Lowes, etc. If you have a low pressure burner, for example, that is rated at 40,000 btu/hr maximum output then you can run that burner at full blast for 10.8 hours: (20# x 21,591btu/# = 431,820 btu is the gas in a 20# tank, 431,820 btu ÷ 40,000 btu/hr = 10.8 hrs) . On the other hand if you have a high heat, high pressure burner that is rated at 160,000 btu/hr maximum output you can run that burner at full blast for only 2.7 hours. In practice, it is unusual for anyone to run a burner at full throttle for that long so you will probably not empty the tank this quickly. The point is that if you want to develop the heat in an uninterrupted manner you have to plan for adequate propane tank reserves. Experienced chefs keep a spare propane tank handy.

These figures are all theoretical. According to a major 20-pound propane tank producer, Blue Rhino, their 20-pound propane tank will only contain about 4.1 gallons of liquid propane which weighs just 17 pounds.  The empty propane tank weighs about 20 pounds so if you add the 17 pounds of gas you have a full propane tank weighing around 37 pounds.  

Folks also ask: "What is the pressure inside my portable tank?"   According to the publication NFPA58, a tank with 20 pounds of gas at 70°F has a pressure of 145 psi, at 90°F would have 180 psi, at 105°F would have 235 psi, and at 130°F would have 315 psi.

 

My propane tank and regulator ice up and the propane output is dropping.

 

Often the source of the problem is water within the small, portable propane tank.  Water is not supposed to be in the tank, but usually is. The propane inside the tank is in a liquid form.  Propane leaves the tank in a vaporized state. That change of state from liquid to gas requires a considerable amount of heat.The heat to vaporize can only come from the metal tank that contains the gas. If the demand for the propane is very high, the tank and regulator get noticeably colder and colder.  If the demand for gas is very high the vaporized propane delivered will decrease. If there happens to water along with the propane stored in the tank, the water vapor will freeze internally at the tank valve and can even freeze within the regulator and will further reduce or block the flow of propane to the supply hose.  This is noticed more profoundly when the demand for the propane is at a high level and/or the amount of liquid propane left in the tank is at a lower level.  Water does not mix with propane but both propane and water have vapor pressures within the tank.  Moving or shaking the tank is not helpful.

  

What can I do when the propane tank and regulator freezes?  

What can you do?   Buy the largest tank you can lug around.  As the internal surface area increases the heat sink increases because the metal cylinder has a larger heat reserve available. You could also complain to your retail gas supplier.  Ask them to purchase the gas from a gas wholesaler that adds some methyl alcohol into the propane. Methyl alcohol acts as antifreeze. Wholesale propane gas suppliers in colder climates often do this in the winter months. If that is not feasible then occasionally pour some hot water over the tank valve and propane regulator.  You can try to keep the propane tank and gas regulator in a warm place. The colder the propane tank and gas regulator gets, the more prone the tank and gas regulator will be to experience a freeze up during high propane demands. Lastly, keep a spare propane tank and be prepared to make a switch whenever you sense a decrease in the flow of the propane.

Caterers often like to use a manual tank changeover valve to quickly change to a warm, full tank by the simple turn of a valve. After you switchover to the new tank the other frozen tank can have time to warm back up or you can changeout the problem or empty tank.  A freeze up will be more pronounced with a less than half-full or a near-empty propane tank, and occurs more frequently in a smaller 5 gallon propane tanks than a larger propane tank. Experienced caterers commonly use as large of a propane tank as they can and keep a spare tank nearby. The use of a twin stage regulator will certainly help reduce these freeze-ups because the gas expansion process is drawing heat from two separate regulators rather than just one.  A twin stage regulator also delivers a more steady and even supply of gas.

 

What is a btu?

   

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A btu, or British Thermal Unit, is the amount of energy required to raise one pound of water one degree Fahrenheit.  

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A gallon of liquid propane contains 91,502 btu's.  

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A pound of liquid propane contains 21,591 btu's.

 

I have a low pressure regulator but it does not seem to supply enough gas for my appliance.

Unfortunately, many of the preset low pressure regulators available in the marketplace use 1/4"ID black hose and most are attached to a propane regulator with only a 1/4"ID NPT (National Pipe Thread Taper) outlet. There is a definite limit to the volume of gas that can be delivered through this small ID hose at a fixed low propane pressure of 6 ounces. 

If you are looking for more details, kindly visit lpg gas cylinder pressure in psi.

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What can I do if my preset low pressure regulator is not supplying enough gas?  Can I increase the pressure of the gas?

No, you cannot increase the pressure.  The low pressure regulator is PRESET at 6 ounces, which is 10.5 WC or Water Column inches. The likelihood is you are using a preset regulator with a 1/4" ID outlet and a black thermorubber hose which has an 1/4"ID. This limits the volume of gas to your appliance.  

You can increase the volume of gas by using a

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The amount of propane that can be delivered to the appliance is increased by a factor of 2.26 so the chances of starving your appliance for propane are greatly diminished. GasHosesandRegulators.com sells only 3/8"ID gas outlet low pressure gas regulators with 3/8"ID low pressure hoses for this very reason.  Our grey hose (3/8" ID) carries UL (Underwriters Laboratories), CSA (Canadian Standards Association), and AGA (American Gas Association) approvals and is designed to supply up to about 100,000 btu/hr of propane gas.  Don't starve your gas appliance; get a 3/8"ID gas outlet low pressure regulator with a 3/8"ID light gray hose.

, you cannot increase the pressure. The low pressure regulator is PRESET at 6 ounces, which is 10.5 WC or. The likelihood is you are using a preset regulator with a 1/4" ID outlet and a black thermorubber hose which has an 1/4"ID. This limits the volume of gas to your appliance.Youincrease the volume of gas by using a low pressure regulator with a 3/8"ID gas outlet and a (light grey) gas hose of 3/8"ID The amount of propane that can be delivered to the appliance is increased by a factor of 2.26 so the chances of starving your appliance for propane are greatly diminished. GasHosesandRegulators.com sells only 3/8"ID gas outlet low pressure gas regulators with 3/8"ID low pressure hoses for this very reason. Our grey hose (3/8" ID) carries(Underwriters Laboratories),(Canadian Standards Association), and(American Gas Association) approvals and is designed to supply up to about 100,000 btu/hr of propane gas. Don't starve your gas appliance; get a 3/8"ID gas outlet low pressure regulator with a 3/8"ID light gray hose.

 

Why does my grill have little or no flame?

  

According to the Coleman company there are at least three possible reasons:

First is that the propane tank might have been improperly filled.  All tanks must be purged of air before being filled with gas. This purging requires filling with a small amount of gas and then emptying. Propane is heavier than air and will force the air out of the tank during the emptying. Filling with gas then can proceed.  If the tank is not purged then the air is the first gas to exit the tank and the grill will either have no flame or a very low flame for possibly over an hour until the air does fully exit the tank.
 
A second cause could be automatic activation of a surge protection device within the propane regulator. If you turn on the tank valve before you fully turn off each of the burner knobs on the grill, the surge protector could sense a leak and activate. The fuel flow will be reduced.  The remedy is to turn everything off, disconnect the tank, and reconnect everything before starting over.  

A third possible cause might be that the tank was overfilled.  All propane tanks are now fitted with Overfill Protection Devices (OPD) which is designed to be activated by a float valve.  The OPD feature prevents overfilling of the tank by shutting off the valve.  A 20% empty space is necessary to prevent the tank from venting large amounts of propane when the ambient temperature rises.  This OPD can also be inadvertently activated by tilting a very full tank during moving.
 

Interesting Facts

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One gallon of water weighs 8.33 pounds.  It takes one btu to raise each pound of water 1 degree Fahrenheit or 8.33 btu's to raise one gallon of water one degree Fahrenheit. Knowing that, it is simple to calculate the number of btu's required to raise a known number of gallons of water to boiling...(assuming 100% thermal transfer of the heat from the flame and knowing the starting temperature of the water).  This is useful in determining approximately how long your tank of gas will last.

 

What is the better fuel, Propane or Natural Gas?

Volume to volume propane delivers more btu/hr than natural gas.

 For example, at 60 °F a flow of 1 cubic foot/hr of natural gas will deliver btu/hr but 1 cubic foot/hr of propane will deliver btu/hr...about 2.5 times more heat.  The reason for this is that methane (natural gas) has one carbon atom bound to four hydrogen atoms and propane has three carbon atoms bound to eight hydrogen atoms.The oxidation (burning) of a propane molecule releases 2.5 times more heat because the process is breaking many more chemical bonds within the molecule.  The end products of the complete oxidation (burning) of both a natural gas molecule or a propane gas molecule are the same, carbon dioxide and water. The difference is that you get a lot more carbon dioxide and water with the burning of the propane and, of course, a lot more heat.  

Natural gas is a reliable and cheap fuel. Many people opt for it if it is available. Propane is the more practical choice if your have a mobile cooking setup.  Our low pressure cast iron burners, pipe burners, and jet burners can be configured with different size orifices to give the same BTU/hr output regardless of which fuel you choose.

 

More propane 101

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A 20# LPG tank theoretically contains 4.72 gallons but in practice may only contain 4.1 gallons since gas cylinders are not supposed to be filled more than 80% full.    

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We provide these propane regulator facts, Propane 101 facts, to help take the mystery out of choosing the right

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One psi equals 27.7 inches of water column.We provide these propane regulator facts,facts, to help take the mystery out of choosing the right high pressure regulator or low pressure regulator If you learned something on this page and it was of help to you please

 

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