RS-51 (R470B)

Is the LOWEST GWP, NON-FLAMMABLE Retrofit Replacement for R404A and R507

  • RS-51 (R470B) has a GWP of 717 which is 80% lower than R404A  R507
  • RS-51 (R470B) has the lowest GWP replacement for R404A and R507

Dear Valued Customer,

We appreciate your interest in our innovative products.

As of January 1, 2018, The U.S. Environmental Protection Agency (EPA) requires buyers of regulated refrigerants containing CFCs, HFCs or HFOs to be certified technicians or registered wholesalers.

If you’re a technician, you will be asked to complete a short form and upload your
license to complete your order in the cart.

If you’re a wholesaler, you’ll need to complete an application and upload a sales and use tax resale certificate. Once you’ve been approved (usually within two business days), you will be entitled to buy our products at wholesale prices.

Thank you!


Comstar International Inc.

Refrigerant Purchase Certification Form

ComStar International Inc.’s RS-51, with the ASHRAE designation of R470B, is new to the U.S. market. RS-51 (R470B) is the lowest GWP at 717 retrofit refrigerant to replace R404a and R507 in EXISTING in-place R404a and R507 systems.

RS-51 (R470B)

RS-51 (R470B) is EPA SNAP approved and A1 ASHRAE certified as non-flammable and non-toxic. The refrigerant does not require design modifications or component changes. RS-51 can operate with existing polyol ester (POE) oils present in R410A systems.

RS-51 is an HFO blend, which is the environmentally friendly alternative to the commonly used HFC blend in other refrigerants. Using RS-51 as a replacement is easy.  Just use the same tools, test instruments, and recovery machines as you use with a R470B system.

ComStar’s RS-51 (R470B) can accommodate state and federal legislation as they phase out high-GWP refrigerants, such as R470B with a 2088 GWP.

RS-51 (R470B) is formulated to be trouble-free and works with all R470B compressors, system components and POE oils. RS-51 has similar properties to R470B, including discharge pressure, discharge temperature, energy efficiency, and cooling capacity. It all adds up to an ideal replacement.

RS-51 (R479B) is suitable to replace R404 and R507 across a range of applications, including supermarkets, cold stores, freezers, ice machines, refrigerated transport, beer cellars, freezer cabinets, transportation of foodstuffs, freeze dryers, environmental test chambers & others. When retrofitting an R404 and R507 system with RS-51, ComStar offers the following guidelines:


Ensure the right equipment is available, such as: recovery unit and cylinders, container for recovered lubricant, vacuum pump, weighing scales, replacement drier, etc.


Before removing the R404A or R507, operate the unit under standard operating conditions and record the pressures, temperatures and any other relevant measurable data to establish unit performance.


Recover and weigh the R404A or R507 from the unit. The weight should be within the range specified by equipment manufacturer.


Replace the filter/drier and evacuate the system.


As in the case of R404A and R507, RS-51 should be used with a polyol ester lubricant.


Before operating the unit, charge the unit with liquid RS-51. The weight added at this stage should be approximately 10% lower than the R404A or R507 charge specified by the equipment manufacturer.


Operate the unit under conditions similar to those used in Step 2, closely watching the liquid line sight glass, the compressor oil level sight glass and the suction superheat.


If the system has an electronic expansive device, select the parameters applicable to R134a. Existing TXVs should be replaced with an R134a valve of similar capacity to the existing valve or modified by replacing the element with an R134a power element of similar temperature range.


Clearly label the system to show it contains R470B (RS-51).


Check system thoroughly for leaks.


Remove all R404A or R507 labels and clearly label system RS-51 (R470B).


Governments around the country and the world are moving to eliminate or reduce high GWP HFC refrigerants. As you plan for a future that rewards the lowest-GWP alternatives for your organization’s cooling needs, discover why ComStar is the smart choice.