Automatic Temperature Compensation and the Retail Sale of Gasoline and Diesel Fuel

An automatic temperature compensator is an electronic device which measures the temperature of petroleum products during delivery and automatically calculates the amount of product as though it had been delivered at 15°C. This practice is known as automatic temperature compensation (ATC).

The volume of gasoline expands and contracts with changes in temperature. Selling gasoline on a temperature compensated basis removes the inequities that can result when the volume of gasoline changes due to temperature fluctuations.

Automatic temperature compensation has long been used when petroleum products are bought and sold internationally and at the wholesale level. The use of automatic temperature compensation at the international, wholesale and retail levels of trade provides a more accurate and equitable approach through the use of a standard reference temperature and benefits Canadians by removing the effects of temperature when purchasing petroleum products.

The reference temperature of 15°C is a long-standing 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.

No. The actual reference temperature used does not matter. In the sale of temperature compensated petroleum products, the volume is based on 15°C. This means that the consumer is paying for a 15°C litre at a 15°C price, no matter what the temperature of the product. If a different reference temperature were chosen, the purchaser would still receive consistent amounts of product. However, a different price per litre would possibly be charged if a different reference temperature were used.

Manual and mechanical temperature compensation has been used in the measurement of large quantities of petroleum products, such as pipelines, ship-loading and tank farm transfers since the 1920's decades and electronic temperature compensation has been used for the retail sale of gasoline for the past 20 years. Prior to the advent of modern electronics, there was no way to perform this function accurately in retail dispensers. In 1984, a Canadian electronics manufacturer designed a device which could readily measure the temperature of liquids and perform the necessary calculations. Now, the vast majority of gasoline pumps in Canada are equipped with automatic temperature compensating equipment. A gas pump equipped with automatic temperature compensation (ATC) shall be identified by a sticker on the register which says "Volume Corrected to 15°C".

Automatic temperature compensation is a more accurate and equitable method of measuring gasoline as it removes the effect of temperature on the volume of gasoline. The purchase and sale of gasoline based on a common reference temperature allows gasoline retailers to sell product on the same basis as it was purchased (facilitating accurate product inventories and early detection of product loss). The use of gasoline pumps equipped with automatic temperature compensation benefits consumers by removing the effects of temperature when purchasing gasoline.

Yes. The use of ATC is mandatory in Canada for the sale of natural gas and retail propane. Its use is optional in the sale of gasoline and diesel because the volume of the latter two fuels changes relatively less with temperature.

All models of gasoline pumps equipped with automatic temperature compensation are evaluated and approved for use in Canada by Measurement Canada. Every gasoline pump is also inspected by a Measurement Canada inspector or a Measurement Canada authorized service provider before it is placed into service to ensure it is measuring accurately. Gasoline pumps are randomly inspected throughout their service lifetime to ensure they continue to measure accurately and are installed and used correctly.

If you think that you have not received the amount of gasoline 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 with the service station owner, you may register a complaint with the local Measurement Canada office. Measurement Canada will investigate the complaint, institute corrective action if the gasoline pump is not measuring accurately and advise you of the investigation.