Propane fuel & equipment

(Survival manual/5. Energy/Propane fuel & equipment)

A.   What is propane?
Propane, or liquefied petroleum gas (LP-gas), is one of the nation’s most versatile sources of energy and supplies 3 to 4 percent of our total energy. As opposed to relying on foreign sources, approximately 90% of the United States propane supply is produced domestically. For years, families and businesses have counted on clean, dependable propane for heating, hot water, cooking, and clothes drying.

The advantages of propane?
There are six very good reasons why you should consider  increasing  propane use in your home energy needs:
1)  Propane has a wide variety of uses: heating, water heating, cooking, clothes drying, swimming pool water heating, hot tub & sauna heating and emergency generators. Propane is also used to fuel cars and trucks.
2)  Propane is a clean-burning, environmentally friendly fuel that can be stored safely in residential & commercial underground tanks.
3)  Propane heating equipment is designed to operate efficiently. Some equipment can be as high as 96% efficient. That means for every heating dollar you spend, you get 96 cents worth of heat.
4)  Propane heats water at one-half the cost of electricity.
5)  Propane heating and water heating equipment can be installed with special direct venting systems which do not need a chimney. This will save you money on retrofitting and unnecessary construction.
6)  Unlike competitive fuels, most of the propane used in the United States comes from North American sources.

Propane is one the easiest fuel source to use. All you do is screw it on and light the gas. Because propane is already under pressure you do not have to pump it or do anything special. Propane has to be under pressure because its boiling point (point when it turns from a liquid to a gas) is negative 44 degrees Fahrenheit. This means that it is normally a gas. In order to turn it into a liquid you need to pressurize it, which is why it is stored in strong metal containers.

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B.  Facts and figures
•  1 pound of Propane = 22,000 BTUs =8.5 cu ft LP gas.
•  20 lb tank of propane holds approx 4 gallons of propane (366,000 BTUs)
•  Your propane appliance will work for x hours= 366,000 BTUs per 20 lb tank propane/ appliance BTU output hrs .
•  Filling a 20lb tanks costs  about $15.
•  100 pound propane tank will hold about 24 gallon. (100 pounds / 4.24 lbs/gal = 23.58 gal.)
•  100 lb tank holds 2,159,400 potential BTU’s, so a 100,000 BTU input furnace could burn 21.59 hours, if your furnace is fired for 25 minutes of every hour (COLD WEATHER), over 8 hours you will get about 6-7 days on a tank.
•  1000 lb propane tank will hold 235.8 gallons. 1000 pound tank / 4.24 lbs/gal=235 gal.
•  Propane contains roughly 20,000 BTU’s per pound, so if you’re using a burner of 20,000 BTUs, a 1 lb cylinder will last 1 hour. If your burner is 2,000 BTU’s you’ve got about 10 hours of fuel in a 1lb cylinder.
•  1 gallon of propane:  weighs 4.24 pounds and produces 91,500 BTUs heat.
•  1 gallon of propane = 27 kWh (Kilowatt Hours) of electricity; this means that one gallon of propane contains the same amount of usable energy as 27 Kilowatt Hours, or we can say that 27 kWh equals approximately 91,500 BTU ( or 4.15 each  1 pound propane cylinders).
•  A 100 watt light bulb left on for a full day (24 hours) will consume 2.4 kWh. If propane were to power the same light bulb (hypothetically remember, we’re comparing energy content) for 24 hours, it would use .09 gallons of propane.

Notes:
•  The cylinders should be transported in a ventilated area and kept as cool as possible and out of direct sunlight if possible. The best option for 1 lb & 20 lb cylinders is a plastic milk crate with a reflective, white sheet/towel covering the top.
•  Propane cylinders are not rated in gallons. They are rated in weight because propane has been traditionally sold by weight. For instance, a standard BBQ cylinder is called a 20 lb cylinder even though it weighs a bit more than 20 lbs when filled. There is a larger one that is common to the RV world and it is 40 lb.. The taller cylinders that are owned by the propane companies are 100 lb, 250 lb and 500 lb cylinders. The horizontal “hot-dog” ones are 1000 lb units or larger.
•  A 100 lb cylinder is about a foot in diameter. Propane weighs 4.24 pounds per gallon. A 100 lb cylinder holds about 24 gallons of liquefied gas.
•  The 100 lb cylinder is subject to recreational tax, that means it will cost you more per pound to fill the 100 pounder than the bulk tank in your yard. If you lease your bulk tank, when you don’t want it anymore they’ll take it away. There is usually a discount for a ” bulk tank ” refill.
•  Buying your own propane tank vs. leasing/renting: “I bought my own 1,000 gallon tank 4 years ago. The difference in the price of propane paid for the tank by the second refill and I shop around every time I need to fill it.”
• Liquid propane will expand to 270 times its volume when it changes from a liquid to a gas. That’s why you can cook for a long time on such a small amount of propane.
• When your home’s furnace pulls full load on a 100 lb cylinder the vapor will freeze, limiting your 100 pounder to 75% useable volume until it thaws out. The reason is that a 100 lb. tank doesn’t the regulator discharge size to supply the needs of a full house furnace, and starves it for fuel.

C.  My propane appliances:
a)  Coleman PerfectFlow 1-Burner Stove: cooks 2.2 hours on High or up to 9 hours on Low. Lasting 3 days per 1 lb cylinder at 72 min/day [1 hr 12 min]);  5- 1 lb cylinders=15 days, 10 lbs=1 month, a 20 lb cylinder=2 months minimal cooking. 1 each 20 lb cylinder theoretically cooks 74 days of meals at 1 hr/day.
b)  Coleman QuickPack InstaStart Lantern:  illuminates 13 hours on Low and 7.75 hours on High with a 1 lb-ounce propane cylinder; 967 lumens. 1 lb cylinder=4  to 6 days cooking with a
two-burner stove or 3 hours of continuous early morning lighting for 4 days.
c)  MR Heater Big Buddy heater: two 20-lb. cylinders heat up to 400 sq. ft. for up to 220 hrs. (9 days).
The formula for calculating how big of a heater you need is the volume of your tent (LxWxH) x 4. A better insulated space might have a multiplier of 3, or even 2. If you camp in a nice 10×10 Eureka tent, tall enough to stand up in–you will probably need at least a 3000-4000btu heater.
d)  Camp Chef Sport Utility DJ-60LW Sport Stove: two 30,000 BTU/hr low-pressure cast burners, 14.75 inches by 7.5 inches by 28.25 inches, 364 sq. inch cooking surface.

Preview of my propane appliances
(see full  discussion in Warehouse/Equipment/My propane appliances. doc)

1 lb Propane bottles – how long can they be stored? (Answers from the Internet)
 •  The propane can never go bad, only the container. Keep them rust free . I’m using a bottle from 1994 in my shop today. All I originally did was wipe it with vaseline and kept the cap on.
•  ‘I had one that was over twenty years old. Worked just fine.’
•  I’ve been able to find half a dozen credible references for using Vaseline on tank fittings from Propane tanks but none against. Propane and Petroleum will not react with each other.

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D.  Read me first: The thoughts and process of refilling disposable 1 lb propane cylinders
At normal atmospheric pressure and temperature, propane is a gas. It’s heavier than air, so it will tend to settle and collect in low spots. That’s what creates the explosion risk when there is a propane leak, and that’s why propane storage locations must be designed to vent outside and not allowed to vent indoors. This is absolutely crucial. Don’t cut corners here.

The propane we purchase is “Liquefied Propane Gas” (LPG), which has been compressed into a liquid and is stored in cylinders designed to keep the propane compressed. The propane is always under pressure, and will tend to escape if you let it. So, the integrity of your storage cylinder is another extremely important safety factor. Don’t skimp. I don’t know what the lifespan of a refilled “disposable” cylinder is, but if it leaks or is visibly damaged, it’s time to get rid of it.

Myth: Larger propane cylinders generate more pressure than small tanks. This is false, they all generate the same pressure, which is dependent on temperature. Lower ambient temperatures produce lower internal cylinder pressures. Higher temperatures produce higher pressures. That’s why one of the guidelines for refilling disposable propane cylinders is not to do it in direct sunlight or on hot days; you could be dealing with very high pressures indeed under those circumstances.

See, what happens inside the cylinder is that the liquid gas vaporizes just until the pressure is sufficient to prevent additional vaporization, which depends on the temperature.

Pressure keeps the propane a liquid. And the vaporized propane gas exerts pressure. So just enough of the liquid vaporizes to maintain the pressure inside the cylinder to prevent any more of the liquid propane from vaporizing.
Now, you come long, open the valve, light your grill, and thereby release some of the pressure inside the cylinder. Propane abhors a vacuum, so the liquid starts vaporizing again to “fill the vacuum” left behind due to your cooking.

So here’s an interesting feature of propane systems: As long as some liquid propane remains in the tank to vaporize, whether it’s 90% full or 10% full, the pressure inside the cylinder remains constant. That’s why you can cook just as well with a nearly empty tank as with a full tank.

OK, back to the subject at hand: refilling disposable propane cylinders. The goal is to move LIQUID propane into the empty cylinder. It does no good to move GAS into the cylinder. The heavier liquid sits at the bottom of a cylinder, and the lighter gas sits at the top-keep this in mind as you continue reading.

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D.  Refilling A Disposable Propane Tank from a Standard 20 lb Cylinder

Step 1: Safety First & Disclaimer
The 16-ounce disposable propane cylinders are such a convenient size for camping that sometimes there isn’t any other alternatives, it’s a shame that even the major suppliers such as Coleman don’t provide refilling recommendations. The reason you don’t hear much about it, though, is that these cylinders are not DOT-approved for refilling. This means that you can’t take your cylinders to the local propane-equipped service station and have them refilled, refilled cylinders can’t be sold commercially and commercial operators can’t transport refilled cylinders across state lines.
Disclaimer : Whenever there is propane there is risk. If you decide to refill your propane tanks yourself, you have to understand that you do it at your own risk.

Step 2: What you will need
First thing, though, you need to purchase one of these refill adapters from Mr. Heater or one of their distributors. Cabela’s sells a similar item called the Mac Coupler, it’s worthwhile to read the negative reviews on their site.
The negative reviews, which are by far the minority, describe some of the difficulties people experience using this adapter. This can be helpful, because there are a few tricks to refilling these cylinders. To obtain the best results, it helps to understand a little bit about how propane works.

Step 3: Gather your empty, disposable 1 lb. cylinders
I collect empty cylinders from the campgrounds I visit. Most of the people throw them away in the recycling basket I collect them. I also collect the plastic caps because I always store my cylinder with them to protect the tread and the Shreader valve. Use bottles that don’t have dents or rust.

Step 4: Chill Empty Cylinder
You need to create a pressure differential between the supply cylinder and the cylinder being refilled. There are two ways to do this: The official way is to chill the empty cylinder. Remember how propane pressure depends on the ambient temperature? If you can keep the supply tank at room temperature and chill the empty cylinder in the fridge for 30-60 minutes, you can create some temperature differential, and therefore some pressure differential.
But even so, many users report that they only get about a half-full cylinder this way. It may take some experimenting to get it to work optimally. Chill the empties longer? Freeze them? I’m not really sure.

Step 5: Warm the 20 lb. Cylinder
Put your BBQ cylinder in warm water (not hot) for about 1/2 hour. This operation increase the pressure in the giver tank. If your bottle is under the sun a warm and sunny day, just skip this step.

Step 6: Weight the empty 1 lb. cylinders
Weight the empty cylinders. My results after weighing about 24 tanks:
Type #1- With plastic Base (Coleman Type) average empty weight : 384 g. This mean a 100% full tank will weight 849 g (384 g tare weight + 465 g of propane)
Type #2- With metal Base Average empty weight : 417 g. This mean a 100% full tank will weight 882 g (417g tare weight + 465 g of propane)

Step 7: The refill process
To do the refill process, follow the sequence:
#1  Plug and screw the refill adapter onto the 20 lb tank FIRST.
#2  Then, screw the empty 1 lb cylinder onto the adapter.
#3  Flip the tanks over, so they’re upside down, as shown in the picture. In this way the vapor pressure in the 20 lb tank is forcing liquid out of the 20 lb. cylinder into the empty 1 lb cylinder.
#4  Open the valve on the 20 lb tank. The instructions say to leave it open for 1 minute, but you will hear the flow of propane stop after 30-40 seconds. When the sound of the flow stops no more gas is being transferred, close the valve on the 20 lb cylinder.
#5  Turn the tanks back into their normal upright position.

Step 8: Weight the refilled 1 lb cylinder to check fill results
For example after filling a  Coleman type tank, its final weight is found to be 797 grams total weight. Then  797 g total weight – 384 g empty = 413 g propane weight 413 g propane in cylinder / 465 g empty cylinder = .888 or 89% full cylinder.

Step 9: Check for leaks and store refilled cylinders
Once you’ve refilled a cylinder, place some soapy water on both valves (the pressure relief valve and the regular valve you connect to your appliance) and check for bubbles/leaks. I’ve never had a leak, but it’s best not to take a chance. I store my refilled cylinders outside  to be safe. Protect the valve threads with a plastic cap.

Sources:
<http://www.instructables.com/id/Refill-Disposable-Propane-Tank-from-a-Standard-BBQ/>
<http://www.navagear.com/2008/04/refill-disposable-propane-cylinders/>