How is ASTM D93 Used?

From performance to safety, flash point is one of the most important parameters used to assess gasoline and other petroleum products. The term describes the lowest temperature at which a combustible liquid begins to release vapours that will ignite when exposed to an ignition source, such as a spark or open flame. The lower the flash point, the sooner the liquid will ignite. Higher flashpoints are generally considered safer as they’re more resistant to heat.

Of all the methods used to calculate the flash points of petroleum products, ASTM D93 is one of the most reliable. The Standard Test Methods for Flash Point by Pensky-Martens Closed Cup Tester outlines a range of test methods to determine flash point in ranges of between 40 °C to 370 °C.

Calculating flash point

Flashpoints can vary dramatically between combustible liquids. For example, standard gasoline has a flashpoint of around -45 °C. In comparison, standard diesel has a flashpoint of around 180°F. While diesel is generally safer when it comes to the risk of explosion, the convenience and efficiency of gasoline make it the fuel of choice for vehicles with spark ignition engines.

ASTM D93 is an accurate way to calculate flash point, though it’s important to remember that temperatures can vary depending on external factors. For example, the level of oxygen in the air and the pressure around the combustible liquid.

Why flash point matters

A good understanding of flash point can help to:

• Improve safety when operating engines, machinery and equipment at high temperatures.
• Determine compatibility with certain kinds of engines and machinery. Ultimately, this helps to extend the lifespan of equipment.
• Assess the quality of petroleum products and ensure it meets industry standards.
• Establish safe storage and handling protocols

Distillate vs residual vs biodiesel

Three different ASTM D93 procedures can be used, depending on the type of liquid being analysed. We take a closer look at each below:

Procedure A

This procedure applies to distillate fuels. For example, diesel and kerosine. Procedure A is also used to assess biodiesel blends, turbine fuels and heating oil.

Procedure B

This procedure is used to analyse residual fuel oils, as well as petroleum blends that form a surface film. It’s also applicable to used lubricating oils and petroleum liquids with certain kinematic viscosity characteristics.

Procedure C

Procedure C is reserved for biodiesel.

When it comes to analysing petroleum products, a deep understanding of available testing methods is essential. The ASTM website currently offers more than 12,000 technical standards, including hundreds designed for use in the oil and gas industry. Find out more about some of the most widely used methods and their applications in ‘Petroleum Testing - A Comprehensive Guide.’ Or check out 'Recent advances in testing the lubricity of diesel fuel' for a more in-depth look at lubricity testing in particular.