The volume of a liquid fuel expands and contracts with changes in temperature. The process of temperature compensation allows for a measured volume of fuel to be adjusted to the volume it would occupy if it were measured at 15 °C. Selling temperature compensated fuel eliminates inequities caused by changes in volume due to temperature variations. An electronic device called an automatic temperature compensator measures the temperature of the fuel during delivery and automatically calculates the amount of fuel as though it had been delivered at 15 °C. The words "Volume Corrected to 15 °C" must appear immediately next to the displayed net quantity on all fuel pumps equipped with an automatic temperature compensator. In Canada, the use of automatic temperature compensation (ATC) is optional on gasoline and diesel fuel pumps, but is mandatory for the sale of propane as an automotive fuel.
Why was 15 °C chosen as the reference temperature for automatic temperature compensation?
The reference temperature of 15 °C is a long-established international standard used in most countries for the purchase and sale of petroleum products. It has been used in Canada for other fuels (e.g., natural gas and propane) for decades.
Would it be better to use a different reference temperature?
A different reference temperature would work as well as the international reference temperature of 15 °C, but would create a discrepancy between countries. Using the international reference temperature of 15 °C ensures that all compensated measurements are comparable. ATC ensures that volume fluctuations due to fuel temperature changes do not cause inaccurate measurement.
Is temperature compensation new?
Since the 1920s, manual temperature compensation has been used in transactions in which large quantities of petroleum products are measured, such as pipeline transportation, ship-loading and tank farm transfers. Electronic temperature compensation has been used for the retail sale of automotive fuel for over 20 years. Prior to the advent of modern electronics, there was no practical way to perform this function accurately for retail pumps. In 1984, a Canadian manufacturer designed a device which could readily measure the temperature of liquids and perform the necessary calculations. Though currently optional for retail gasoline and diesel pumps, the vast majority of these devices in Canada are equipped with an automatic temperature compensator. The words "Volume Corrected to 15 °C" must appear immediately next to the displayed net quantity on all fuel pumps equipped with an automatic temperature compensator.
What are the benefits of using fuel pumps equipped with an automatic temperature compensator?
The use of fuel pumps equipped with an automatic temperature compensator benefits consumers and retailers by removing the effects of temperature variation when purchasing and selling fuel. The use of a common reference temperature allows retailers to sell their product on the same basis as it was purchased, which facilitates accurate product inventories and early detection of product loss.
Is automatic temperature compensation used in the sale of all fuels?
In Canada, the use of ATC is optional in the sale of gasoline and diesel fuel, because the volume of these fuels is less affected by changes in temperature. However, its use is mandatory for the sale of propane as an automotive fuel.
Is the automatic temperature compensator on fuel pumps tested?
Yes. All models of fuel pumps equipped with an automatic temperature compensator must be evaluated and approved for use by Measurement Canada before they may be used in retail trade. Every fuel pump is also inspected by a Measurement Canada inspector or authorized service provider before it is placed into service to ensure it is measuring accurately. Fuel pumps are periodically inspected throughout their service lifetime to ensure they continue to measure accurately and are installed and used correctly.
What should I do if I think a fuel pump is not measuring accurately?
If you think that you have not received the amount of fuel you paid for, you should first speak to the service station owner to try and resolve your concerns. If you are unable to resolve the matter, you may file a complaint with the local Measurement Canada office. Measurement Canada will investigate the complaint, institute corrective action if the fuel pump is not measuring accurately, and advise you of the results.