Refrigerant R-410a

R410A is a blend of HFC-32 and HFC-125 (50/50 wt %). It is an azeotropic refrigerant. It performs very much like a single component refrigerant. The physical and chemical properties of R-410A are very similar to those for R-22 as well as most of today's HFC refrigerants. In 1996 the EPA formally recognized R410A as a substitute for R22. Leading chemical companies have made a strong effort to sell R410A to air- conditioning manufacturers as a long –term replacement for R22.Following are some of the positive points for considering R410A as an alternative to R22 especially for new A.C Systems.

• Higher Capacity Equipment: Equipment designed for R410A has demonstrated up to 40% greater capacity when compared to current HCFC-22 equipment. It allows for smaller equipment sizes. Majority of the customers prefer smaller size equipment.
• Easy Servicing: As it is azeotropic mixture it behaves almost like a pure refrigerant and therefore it can be repeatedly topped off.
• Safe and Easy to Use: R410A has an A1 ASHRAE safety classification, which means it has lower toxicity and no flame propagation.
• Higher Efficiency: R410A systems exhibit about a 10% increase in the Coefficient of Performance.

Some of R410 properties are given in table 1

Table1

This reft operates at a significantly higher pressure than R22. This may seem to be a negative characteristic of this refrigerant; but this negative point has forced the designers to design more robust design and superior control & protection techniques. Because of the higher pressure for R-410A, most system components have been designed with increased wall thickness. Due to the robust design the system reliability has improved.R410A pressure drop is also less than R22. A LEED pre-requisite is that HVAC equipment must not use a CFC refrigerant. R410A is one of the green refrigerants and can earn extra LEED point. It is to be kept in mind that R410A can not be used as retrofitting refrigerant applications because of the higher pressures associated with it.

Servicing and safety

Most R410A systems use a Polyolester lubricant (POE). It is to be noted that POE lubricants readily absorb moisture and therefore minimize exposure of lubricant or internal parts of the system to the atmosphere. Proper care should be taken while handling lubricant of this refrigerant. Following are few tips to handle the POE lubricant.

· Don't store POE oils in plastic containers. Use glass or metal.

· POE oils can cause skin irritation and therefore use gloves and use care when handling lubricant.

· Wash any exposed skin with soap and water to remove lubricant.

For detecting leak electronic leak detectors can be used but the detector must be capable of detecting a HFC refrigerant. It is to be noted that older leak detectors designed for R-22 may not be sensitive enough to detect R410A.Use of halide torches should be avoided as these torches cannot effectively detect R410A refrigerant leak from the system. Using soap solution is not advisable as small leaks may not be detected with soap solution. UV sensitive dyes can also be used effectively.

Service technicians who work on R410A systems should use approved service tools to handle the high pressures of the system. These includes-gauges manifold gauge sets require a 800 psig high-side with a 250 psig low-side & all hoses should be rated for 800 psig. Recovery cylinders require a 400 psig service pressure rating and use cylinders approved for R410A.