Is There A Problem With The Quality Of Propane Fuel?

There has been some concern that the quality of the propane used to fuel some forklifts has not been good. There appears to be no evidence that anything is wrong. However, the concerns have shown a need to explain fuel standards recognized by the liquid gas industry.

Propane Grades

There are three basic grades of propane in the United States –-

• Commercial Grade – Up to 49% propylene and other gases and used for home heating, appliances and commercial heating operations.
• HD10 – minimum 90% propane or up to 10% propylene
• HID5 (Special-Duty Propane) – minimum 90% propane, maximum 5% propylene, or remaining 5% to consist of other gases, such as iso-butane and methane.

Forklifts designed for propane fuel use HD5 fuel. This is because propylene can cause fuel systems and engine components to “gum-up” or stick when the lift is operating. There is also some thought that propylene can cause damage to emission control components.

It is suggested that you enquire as to the grade of the propane you’re using. Never settle for less. It could cause problems with the maintenance and reliability of the forklift.

There is also a concern for contaminates that could be in the propane. These contaminates can be introduced when the fuel is making its way through the distribution chain. It should be noted that most distributors do a good job filtering contaminates from the fuel. However, not all contamination is removed during the filtering process.

Preventing Contamination In The Fuel Line Of A Propane Forklift

Propane forklift.
(Courtesy: Lori at

So why is there concern for problems with the fuel? The Environmental Protection Agency has released new standards due to the introduction of more complex fuel systems that include injectors, sensors, and computer controls. These items have increased efficiency, but make the fuel system more susceptible to contamination.

What you can do to lessen your concerns include:

• Clean the fuel system of the forklift on a regularly.
• Use the drain located in the vaporizer section of the fuel system to remove tars and residue that may build up.
• Follow the manufacturers instructions concerning maintenance regularly.
• Check to see if the cooling system is working properly and at peak efficiency and that the thermostat is working properly.

Although it is true that there has been an introduction of additives meant to reduce buildup and lower fuel consumption, it appears that these additives do not have a measurable effect on the fuel.


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