Klea R-473A: the low-GWP refrigerant for ultra-low temperatures

With the refrigeration industry looking for low-GWP alternatives to products such as R-23 and R-508A/B, Koura has designed a virtually identical solution for temperatures between -50 °C and -75 °C.

This revolutionary refrigerant, Klea 473A, is the latest addition to Koura's range of technologies designed for use in cascade refrigeration systems, such as climate chambers, low-temperature cold chains and industrial applications.

Klea 473A offers the following benefits to users:

• Klea 473A is a low-GWP alternative to existing products such as R-23 and R-508B, offering up to 85% reduction in GWP
• ASHRAE classification A1 - Klea 473A has been classified as A1 by ASHRAE and is in the same category as R-23 / R-508, which is non-flammable and has low toxicity
• Performance – performance is similar to that of R-23 and R-508, with some particular nuances relating to valve operation, expansion valve sizing, charging and system operation. For best results from the system, maintain suction pressure above 0.5 barg
• Easy to install – Klea 473A has been designed to be a low GWP alternative for cascade refrigeration systems using R-23 / R-508A/B.
• System operation – During operation, the system functions like existing systems, making Klea 473A a very similar replacement for current heat exchangers. Compared to other similar products (R469A and R472A), R473A can use current compressors and operates at suitable discharge temperatures and cooling capacities.

Applications:

Klea 473A is an ASHRAE A1-classified refrigerant (non-flammable, low toxicity) designed to be a low-GWP alternative for low-temperature cascade refrigeration applications R-23 / R-508A/B, where temperatures from -50 °C to -75 °C are required.

Potential applications for Klea 473A include climate chambers, low-temperature cold chains and industrial applications.

Refrigerant charging guidelines:

Although Klea 473A has been designed to be a near-perfect replacement for R-23 cascade systems, it is important to note that each system may vary depending on the application and configuration.

Klea 473A has a higher volumetric capacity than R-23

• If you are using Klea 473A in an existing system, you may find it useful to reduce the compressor displacement/speed to avoid overloading the upper stage of the cascade
• Klea 473A has less pressure loss than R-23 for the same cooling capacity

The compressor discharge temperature is higher for Klea 473A

• Klea 473A has a discharge temperature 10-20 K higher than R-23

The condensing pressure of Klea 473A is higher than R-23

• We recommend adjusting the expansion valve because the pressure drop is higher and the required mass flow rate is lower

Charge quantity

• Although individual systems may vary, we think starting with 90% of the mass of R-23 is a good idea. The precise charge will depend on how the liquid is distributed in the unit when it is running at full capacity

Evaporator pressure

• To prevent dry ice formation, we recommend a minimum evaporator pressure of 1.5 bar (0.5 barg). This can also be achieved with an electronic pulse expansion valve

Klea 473A is supplied in 13-litre cylinders with a charge of 10 kg in each cylinder. The cylinders have no dip tube and are fitted with a CGA 32 valve.

To charge a refrigeration unit, we recommend keeping the cylinder at a minimum temperature of 35 °C to ensure that the refrigerant is in a homogeneous gaseous phase.

Temperature-controlled heating blankets/bands are available in the welding sector.

Once the cylinder has been emptied, contact GeneralGas to arrange for its return.

Applications:

• Industrial cooling systems
• Pharmaceutical production systems
• For medical use (e.g. blood banks)
• Material testing.
• Cryomats and cryostats.
• High vacuum.

Lubricants:

R-473A is compatible with POE synthetic lubricants.