For many years now, technicians have been using a variety of flammable refrigerants in their pure state, or as component of a blend. Using a small amount of a hydrocarbon (HC) refrigerant blended with other refrigerants to improve oil return has been a common practice in the air conditioning and refrigeration industries for many years.
ICOR brought this practice into the mainstream by adding an HC component to its proprietary direct replacement refrigerants, thus helping refrigerant users and equipment owners avoid a costly system oil change. The added HC allows hydrochlorofluorocarbon (HCFC) and hydrofluorocarbon (HFC) refrigerant blends to be compatible with all standard refrigeration oils.
Since the CFC/HCFC phase out began, technicians have been exposed to a great deal of new refrigerant terminology including the term "Drop-In", which is a surrogate word used for Alternative Refrigerant or Direct Replacement. The Drop-In term —which is even used by ASHRAE — is often misinterpreted to mean that it's okay to "drop" one type of refrigerant directly "in" to a system containing a totally different refrigerant. The terms Drop-In, Direct Replacement, and Alternative Refrigerant, describe refrigerants that can be used in systems originally designed for use with a different refrigerant, and could be done so with limited system modifications.
ICOR's direct replacement for R-12, HOT SHOT® (R-414B) is a great example. Hot Shot has proven to work very well in systems originally designed for use with R-12, but it was never meant to be mixed with R-12. The following chart shows the ASHRAE flammability class of the most widely used refrigerants. There is no reason for concern if you have used, or preparing to use, a drop-in refrigerant in a system that is not designed for use with flammable refrigerants, providing the drop-in refrigerant is ASHRAE classified A1 (No Flame Propagation).
All of the blends listed below that contain a flammable component do not pose a flammability risk.
ASHRAE Standard 34 Flammability Classifications
A1 (No Flame Propagation) A2/2L (Lower flammability) A3 (Higher Flammability)
A1 Refrigerant Blends That Contain a Flammable Component
R-401A/B, R-402A/B, R-404A, R-407A-F, R-408A, R-409A, R-410A, R-414A/B, R-416A, R-422A-D, R-427A, R-438A, R-500, R-502, R-507
A1 Pure Refrigerants (single molecule)
R-12, R-22, R-124, R-125, R-134a
A2/2L Pure Refrigerants (single molecule)
R-32, R-142b, R-143a, R-152a
A3 Pure Refrigerants (single molecule)
*R-290 (propane), R-600 (Butane), R-600a (Iso-Butane), R-601A (Isopentane)
A major concern in our industry today is the careless promotion of hydrocarbons, or hydrocarbon based blends, as drop-in refrigerants. Even though HC's do have many positive attributes, in their pure state they are classified A3 and therefore if misapplied can be very dangerous to use. Safety should always be a top consideration when determining what refrigerant to use in any system or application.
There are many documented cases where the improper use and handling of an HC resulted in a loss of life and/or property.
Compressor and equipment manufacturers design units specifically for flammable refrigerants. They are very different than systems designed for use with common CFC, HCFC or HFC refrigerants. The risk of explosion is very high when an air conditioning or refrigeration system leaks an HC or HC-based refrigerant. Potential ignition sources such as on/off switches, contactors, relays, pressure switches, lights, or any other electrical component can easily ignite a highly flammable HC.
There are many documented cases where the improper use and handling of an HC resulted in a loss of life and or property. How many times have you opened the back of your service van to discover that a refrigerant cylinder has leaked completely out? Just think what could happen if the refrigerant was an HC. Your door light switch or dome light itself could be a perfect ignition source. And if you're a smoker and decide to "light up" with a van full of near odorless HC vapor, the outcome could be deadly.
Today there are a number of companies promoting HC based "drop-in" refrigerants that lure users in with the promise of cheap prices, great performance, and the claim they are okay to be mixed with existing refrigerants. These relatively unknown companies try hard "not" to tell you their products are HC based and highly flammable. They are very reluctant to provide a product specification sheet, MSDS, or the ASHRAE number for fear the potential buyer will look to see what the product's components are. Anyone can legally promote and sell an HC for use as a refrigerant, providing however it is listed on the EPA's SNAP list (Significant New Alternative Policy). The legal use of flammable HC refrigerants is limited to a small number of applications. Topping off or mixing an HC based refrigerant with a non-flammable refrigerant in an existing system can, depending on the concentrations of both products in the system, present a serious flammability concern and be in violation of SNAP.
For more information on accepted HC applications go to epa.gov and search "SNAP List", or call ICOR's toll free Tech-2-Tech hotline, at 866/433-8324. Refrigerant users and equipment owners can avoid potential liability by only using non-flammable ASHRAE A1 classified refrigerants. Be very sure you know exactly what a refrigerant is made of before buying or using it. All legitimate and responsible refrigerant producers offer comprehensive product specification sheets, MSDS, and other educational resources that promote proper handling and use of their refrigerants.
Jamey Hale is a NATE-certified technician with over 30 years of service experience in the commercial HVACR industry. He is a Certificate Member Specialist of the Refrigeration Service Engineers Society and has been a Technical Support Supervisor for ICOR International, Inc. since 2003.