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Little Known LP Gas Facts

Larry Hinckley

New member
LP Gas Facts
By Larry Hinckley, Senior Technical Advisor
Delco Cleaning Systems of Fort Worth, 2513 Warfield St., Fort Worth, Texas 76106-7554
Phone: 800-433-2113; Fax: 817-625-2059
LP-Gas (liquid petroleum gas, or propane)
LP-gas is a gas compressed into liquid form for easy transportation and storage. It is also known as propane or bottled gas.

LP-gas is flammable, is always contained under pressure, and the liquid can freeze skin. Therefore, in the interest of safety, it is important to understand the basic facts about LP-gas and LP-gas containers.

Federal DOT (Department of Transportation) regulations require periodic inspections and re-qualifications of cylinders. DO NOT USE damaged or rusted containers.

CAUTION: USE LP-GAS CONTAINERS IN PROPER POSITION
Most LP-gas pressure washer heaters are designed to operate on LP-gas vapor only. Therefore, all LP-gas containers designed for vapor service must be transported, installed and used in the proper position. Do not transport, install or use a vertical cylinder in a horizontal or upside down position. Proper care must be taken to position a horizontal container in the correct position for vapor withdrawal. Liquid LP-gas could enter the system designed for vapor only, possibly creating a hazardous condition.

Always use a POL plug installed on a POL valve or a dust cap on an ACME/Type 1 valve when transporting or storing disconnected containers (full or empty).

All LP-gas containers must be securely attached in the proper position for intended use.

ADVANTAGES OF TWO-STAGE REGULATION
Reduced Freeze-Up Problems - According to national code, a two-stage regulator must be used on RV's. A two stage regulator greatly reduces the possibility of freeze-ups. This is a positive safety factor.

Improved Regulation - The second stage regulator receives a relatively uniform pressure from the first stage regulator. This helps the second stage regulator to maintain appliance pressure at a nearly constant 11" W.C.



FILLING YOUR LP-GAS CONTAINER
Only qualified persons should fill your LP-Gas containers.

CAUTION: OVERFILLING IS HAZARDOUS! Do not allow your LP-gas container to be overfilled. Stop filling when liquid appears at the fixed level gauge. Bleed off excess propane in a safe area. Most LP-gas containers are equipped with a fixed liquid level gauge which contacts the liquid level at 80% of container capacity, allowing 20% for expansion. LP-gas containers not equipped with a fixed liquid level gauge can only be filled by weight.

LP-gas containers must not be filled over 80% of total capacity. Propane expands approximately 1.5% for each 10º F temperature rise. Pumps do not stop filling "automatically." Pumps "by-pass" when containers are dangerously filled to total capacity. If overfilled, excessive pressure could develop within the container causing the relief valve to open, relieving excess pressure. LP-gas released through the relief valve is flammable.

The fixed liquid level gauge is used only to determine safe fill levels and does not indicate lower levels. LP-gas containers are available with visible gauges that monitor the amount of gas in the container at all times, reading from full to empty. Do not use visible gauges for filling.

BASIC FACTS ABOUT LP-GAS*

Pounds per gallon
4.24

Specific gravity of gas
1.50

Specific gravity of liquid
.504

Cu. ft. gas per gallon liquid
36.38

Cu. ft. gas per pound
8.66

BTU per gallon
91,502

BTU per pound
21,548

Dew point in degrees F
-44

Vapor pressure at 0° F
31

Vapor pressure at 70° F
127

Vapor pressure at 100° F
196

Vapor pressure at 110° F
230


In cold climates, in order to keep vaporization of LP-gas at the highest level, keep the fuel levels above 50%.



AVERAGE LP-GAS
CAPACITIES IN CYLINDERS

# Capacity Gallon Capacity BTU Capacity
5 1.18 107,903
10 2.36 215,807
11 2.59 237,387
20 4.72 431,613
30 7.08 647,420
40 9.43 863,226


The above capacities allow for the 20% vapor space on each cylinder.

As you can see from the above chart the smaller cylinders will not work on large heaters.

CONVERSIONS
Gallons to Liters (1 gallon = 3.785 liters)
F° to C° (F° = 9/5 C° + 32°)
11" Water Column = 6-1/4 oz. per sq. in. pressure
27.7" Water Column = 1 pound per sq. in. pressure

*Data from NFPA (National Fire Prevention Association) Pamphlet #58-1998

Note: The above information is not meant to be a complete guide to the use of propane cylinders and appliances.



PURGING OF AIR FROM LP-GAS CONTAINERS
Air in LP-gas containers is a contaminant. Purging is done prior to initial filling to remove the air. If the container is not properly purged, air in the container dilutes the LP-gas vapor. Failure to purge may cause excessive tank pressure, slow filling and poor appliance operation of Automatic Stop Fill valve. Appliances then require constant adjustment and pilot lights won't stay lit. This condition would exist until all air is depleted, leaving pure LP-gas vapor.

Have your LP-gas container purged. It only takes a few minutes and your LP-gas dealer is equipped to perform this service (see NPGA bulletin 133-a)





COMMON TERMS OF LP-GAS TANKS

1. POL, ACME and QUICK DISCONNECT VALVES - Types of vapor withdrawal service valves.

2. Fixed Liquid Level Gauge - Clear vapor less than 80%; white mist 80% or above.

3. Vapor Withdrawal Tube - Used on tanks where service valve is not located on top of tank.

4. Base ring, stand legs, or mounting brackets.

5. Relief Valve - discharges LP-gas if the pressure in the container is too high. If LP-gas is discharging, call the Fire Dept. and get away from the container.

6. OPD - or Overfill Prevention Device is a valve, designed to assist LP-gas fillers to fill the cylinders to safe levels of propane.

7. Automatic Stop Fill Valve - with 1-3/4" ACME

8. Visible Sight Gauge - Available with remote sender.

DOT AND ASME CONTAINERS
Generally speaking, LP-gas tanks are built to the specifications of either the ASME Boiler and Pressure Vessel Code or DOT Hazardous Materials Regulations.

Basically, the difference between the two is stationary use (ASME) and transportable use (DOT). These containers are required to be rated in gallons (ASME) or pounds (DOT) water capacity.



LP GAS REGULATORS
LP-gas regulators reduce the pressure of LP-gas vapor from tank pressure to 6-1/4 oz. or 11" W.C. for use at the appliances. The regulator is the heart of the LP-gas system. Care should be taken to protect it from the elements which could cause it to malfunction. Your LP-gas system should be kept free of moisture which could cause regulator freeze-up. A good regulator enclosure will protect your regulator.

CAUTION - ALWAYS BE SURE THAT THE REGULATOR VENT IS POINTING DOWN WITHIN 45 DEGREES OF VERTICAL.







SOME BASIC PRACTICES TO ENSURE SAFETY AND TROUBLE FREE USE

1. Never allow your LP-gas container to be filled above the maximum safe level as indicated by a scale or the fixed liquid level gauge (outage). Do not use the visible gauge for filling.

2. Do not use a wrench or pliers to close the service valve or fixed liquid level gauge. These valves are designed to be closed leak-tight by hand or screwdriver as appropriate. If wrenches are necessary to stop a leak, the valve needs repair or replacement.

3. When tightening the POL Nut (left hand thread) on the service valve, draw it up snug with a proper wrench. This is a machined male brass fitting which seats securely against a female seat in the POL valve - no pipe dope is necessary. Acme/Type 1 valves have right handed threads which are secure when hand tight, and on the Quick Disconnect/Type 2 Valves, the male connection is inserted into the female connection on the cylinder valve. (No wrenches required for both the Acme and the Quick Disconnect.)

4. When using container, slowly open service valve all the way. Listen to the regulator. A continuous hiss may indicate a leak or an open valve on an appliance.

5. Check all tank and the line connections periodically to be sure they are tight. When testing for leaks, use approved leak detector solution - not matches.

6. Make certain your container is properly fastened in place.

7. Turn container with open part of container guard towards trailer (travel trailer installation). This protects valves and regulator against flying rocks and mud. Transport container in the proper position in which it is used, with the valves closed and POL Plugs inserted for POL Valves, or Dust Caps for Acme Valves. Secure the tank against falling or rolling.

8. Check for leaks after connecting. Apply approved leak detector solution to connection, turn off all burners and pilots, and open service valve. Leaks will be detected by the growth of the bubbles. If bubbles grow, tighten or repair the connection as needed. Repeat leak test until problem is corrected.

9. LP-gas is normally non-corrosive - you need not worry about the inside of your container. However, the outside should be kept free from rust by a periodic coat of paint in a light reflective color. It is very important to inspect and maintain the bottom and foot ring on the container.

10. Do not store LP-gas containers indoors or in enclosed areas. Do not expose LP-gas container to heat. Always store with service valve closed and plugged as required.

11. Do not attempt to repair any containers, container valves, regulator or appliances by yourself. Use only trained certified LP-gas service personnel to perform repairs.

For more answers to your questions please call Larry Hinckley at Delco Cleaning Systems 1-800-433-2113.


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