One of the first questions you need to ask when purchasing an asphalt solvent, asphalt cleaner, or asphalt release agent is whether it is a safe product to use. When comparing solvents and degreasers like diesel fuel, citrus, and PavePro–there is a clear winner when it comes to safety. Let’s look at why that is and what is so daggum important about flashpoint.
The flash point of a solvent “is the lowest temperature at which the substance evaporates to form an ignitable mixture with air in the presence of an igneous source and continues burning after the trigger source is removed.” That is chemistry talk for the temperature that your solvent begins to evaporate, and in the presence of intense heat, a spark, or a flame can ignite and explode or catch on fire.
Flash point is no joke. Substances with low flash points put your equipment and your workers at risk of severe injury or death. Not only is flash point dangerous, but it indicates flammability and Resource Conservation & Recovery Act (RCRA) hazardous waste classification and should be included in Section 9 of the SDS, which covers physical and chemical properties.

Measuring flash point

There are plenty of ways to measure flash point, but in construction one method reigns supreme: the Pensky-Martens closed-cup test. This test is the most common and provides the construction industries, particularly the asphalt industry, the best approximation of the true flash point of a product.
The test is administered by filling a brass testing cup with the asphalt solvent or cleaner and heating and stirring the specimen at specified rates. An ignition source is then directed into the cup at regular intervals, pausing the stirring, until a flash is detected. The flash point is then recorded and corrected for barometric pressure.
A Pensky-Martens closed cup flash point analyzer

A Pensky-Martens closed cup flash point analyzer

The various flash points of asphalt solvents

Before we discuss the importance of flash point and how it relates to safety and effectiveness in your asphalt paving operations, let’s take a look at the flash points of diesel fuel, citrus cleaners, and PavePro’s asphalt solvent and release agent.
  • PavePro – up to 400 degrees Fahrenheit
  • Diesel – 130 degrees Fahrenheit
  • Citrus – 115 degrees Fahrenheit
As you can see, the flash point of diesel fuel is around 125 degrees Fahrenheit. Citrus cleaners are even lower hovering around 110-120 degrees Fahrenheit. PavePro is superior to diesel and citrus with a flashpoint recorded at well over 200 degrees Fahrenheit, but closer to 400 degrees in most scenarios.

The importance of flash point

A low flash point is not worth the risk presented by diesel fuel and citrus. It poses red flags like unsafe work environments, hazardous waste classification, and decreased effectiveness. It goes without saying: it ain’t worth it.

Solvents with low flash points are unsafe

These flash points are all based on closed-cup measurements, but even in open area and non-lab settings, diesel fuel has caused many asphalt-related explosions. reported an asphalt explosion that left the lids on top of the asphalt baghouse miles from the site of the combustion. The man spraying diesel on the silo was engulfed in a fireball leaving him disabled and unable to work for the rest of his life.
Looking at the damage caused by one of these explosions speaks volumes. Diesel fuel is dangerous. There are no exceptions to that. And unfortunately, citrus cleaners are even worse than diesel when it comes to flash point.

Solvents with low flash points are considered hazardous waste

Flash point is used as one of four criteria when determining whether a substance is labeled by the EPA as RCRA hazardous waste. Because a material must only meet one of the four criteria to be labeled as hazardous waste and the threshold is a flash point less than 140 degrees Fahrenheit, both diesel fuel and citrus cleaners are considered hazardous waste products.
Hazardous waste poses many problems for asphalt crews. The EPA classifies hazardous waste as dangerous to both humans and the environment. This is why you see lists like the National Transportation Product Evaluation Program’s (NTPEP) approved products lists for various DOTs. For many contractors, they cannot even bid on government jobs without using an approved product that is not classified as hazardous waste.
If you aren’t required to use a certain product by the DOT, you can get in trouble with the EPA if you are found in violation of the Clean Water Act with fines up to $180,000. For paving crews who tend to use asphalt release agents, asphalt cleaners and solvents and degreasers at shops, laydown sites and asphalt plants, using a RCRA hazardous waste product like diesel fuel or citrus is both risky and unsafe.

Solvents with a low flash point are less effective over time

The flash point of a solvent does not directly affect the power of the solvency, but it does affect how long the solvent can work. The flash point is directly related to the evaporation rate. A solvent or release agent with a low flash point will evaporate in high heat much faster than a solvent or release agent would with a high flash point. This means that the material has less contact time on the asphalt and will have less time to actually break down the bitumen in the asphalt.

PavePro is the end-all solution

Our team developed PavePro to replace the use of diesel fuel and citrus for cleaning and removing asphalt from tools and equipment. With a flash point reaching up to 400 degrees Fahrenheit, it is much safer to use in paving operations, avoids EPA fines, and does not evaporate. This means you can spend more time paving without having to worry about hazardous materials or explosions on the job site.
Not only is our asphalt remover safer and legal, it works as well as diesel fuel at cleaning the asphalt and leaving behind that slick oily film that everyone loves from the original asphalt release agent.