Choosing an Explosion Proof Ultrasonic Cleaner
While traditional ultrasonic cleaning methods use water-based cleaners, there are many cases where the use of a flammable cleaning fluid is required. For example, isopropyl alcohol (IPA) and acetone are often desirable as they are effective degreasers and evaporate quickly after cleaning, without leaving a residue. However, the use of flammable or combustible substances in an ultrasonic cleaner creates a hazardous environment. To ensure the safety of personnel and prevent damage to surrounding equipment, an alternative setup must be used. An explosion proof ultrasonic cleaner is specially designed for use with flammable materials. In this article, we discuss more about why you might need an explosion proof ultrasonic tank and the factors you need to consider when deciding on the best cleaner and setup.
Ultrasonic Flammable Liquid Cleaning Applications
Most ultrasonic cleaning applications involve solvents that don't present a risk during the cleaning process. However, some situations call for the use of flammable solvents. According to the Occupational Safety and Health Administration (OSHA), a flammable liquid is one that has a flashpoint below 199.4F (93C). The flashpoint is the lowest temperature at which the vapors of a volatile material will ignite when exposed to an ignition source. According to the National Electrical Code (NEC), a hazardous environment is created whenever flammable solvents are used, as fumes can be easily ignited by any ignition source. Possible ignition sources include any nearby electrical equipment, even an ultrasonic cleaner itself. What's more, ultrasonic cleaning causes a temperature increase in the cleaning fluid. When using a flammable solvent, the rise in temperature will cause evaporation and fumes will accumulate above the tank. Even seemingly harmless static electricity could act as an ignition source for these vapors. A flammable solvent ultrasonic tank is specially designed to enable you to work safely with volatile cleaning fluids such as IPA, ethanol, methyl ethyl ketone (MEK), hexane, cyclohexane and acetone.
Image of a Flammable Solvent Ultrasonic Cleaner
Choosing an Explosion Proof Ultrasonic Cleaner
Here are the key considerations when shopping for an explosion proof ultrasonic cleaner:
Unit Size
Size is one of the main factors to bear in mind when purchasing flammable solvent ultrasonic cleaner. You need to ensure you purchase one that's large enough for your current and future needs. If you're cleaning small components such as watch parts or circuit board components, you may be able to opt for a compact, portable model.
Solvent Flashpoint
The table below shows the most common flammable solvents used in ultrasonic cleaning along with their flashpoints:
| Solvent | Flashpoint (°F) |
| Isopropyl Alcohol | 53 |
| Acetone | -4 |
| Toluene | 40 |
| Methylated Spirits (Denatured Alcohol) | 57 |
| Cyclohexane | -4 |
Bear in mind that just because an ultrasonic cleaner is explosion proof does not automatically mean it can be used with all flammable solvents. For example, some smaller units can only handle solvents with a minimum flashpoint of around 50°F. Looking at the table above, you can see that this would render you limited in terms of which solvents you can use. That said, the cleaners we offer can handle all
Compliance
The most important consideration when selecting an ultrasonic cleaner is to ensure it meets all standards and regulations. Per the NEC classification method, explosion proof ultrasonic cleaners must be Class I, Division 1 compliant. Bear in mind that in order for the cleaner to meet Class I, Division 1 (CID1) standards, the environment in which it's operated needs to meet certain requirements too. These include not having any ignition sources within a certain distance from the unit. The cleaners we help develop are CID1 compliant, and listed by ETL. An ETL approved ultrasonic tank is compliant with national standards and has undergone testing by a Nationally Recognized Testing Laboratory (NRTL).
Considerations When Using an Explosion Proof Ultrasonic Cleaning Method
Although explosion proof cleaners are specially designed for use with flammable solvents, you still need to take steps to ensure safety and efficiency. Here are some of the main things to bear in mind:
Ventilation
When using any flammable solvent ultrasonic cleaner, it's important to ensure you're working within a clean and well-ventilated environment. If you lack ventilation, built up fumes could ignite outside of the cleaner. What's more, if the area is dusty, this can further increase the risk of ignition.
Electrical safety
Electrical safety is important in any setting, but even more so when you're dealing with flammable substances. We mentioned the electrical safety of the ultrasonic cleaner itself above, but it's important to ensure all electrical equipment in the area is safe. The National Fire Protection Code (NFPC) mandates that a CID1 envelope should extend five feet in every direction around the vapor source (flammable solvent). This means that any electrical device within that distance must be CID1-rated, enclosures should be inerted, and circuits have to be intrinsically safe. Devices that may generate a spark must be housed in a CID1-rated enclosure specifically designed for controlling ignition.
Degassing
Degassing isn't specific to explosion proof cleaners but it's an important step nonetheless. Ultrasonic cleaning works by a process called cavitation whereby bubbles form and collapse, dislodging contaminants from objects in the tank. When you add the cleaning solution to your tank, air is naturally trapped inside it. This can interfere with the bubbles produced by the ultrasonic transducer and inhibit the cavitation process. Many flammable solvent ultrasonic cleaner have a degassing mode, but it's possible to degas manually by letting the cleaner run without a load. Removed discussion around using a flask or beaker in a regular ultrasonic cleaner.