Considerations on Adopting R404A Instead of R22

Because R22 destroys the ozone layer and has a high greenhouse effect, more and more refrigeration equipment is using R404A to replace R22. Although R404A and R22 have similar refrigeration performance, there are still many differences between the two in actual use.

When replacing R22 with R404A, the following issues need to be considered:

1. The biggest problem of using R404A to replace R22 is the lubricating oil issue, which must be matched with PVE ester oil to replace the mineral lubricant for R22. Ester lubricant has high affinity with water and poor dehydration, so it should avoid contact with outside air as far as possible in use, after the container is opened, it should be used as soon as possible and must be sealed and kept after use; keep away from oxidizing agents, strong alkalis and strong acids, and keep in a well-ventilated place; avoid contact with skin and eyes when using, and avoid inhaling its vapor and spray.

2. The exhaust pressure of R404A refrigerant is about 1.2 times of R22, the mass flow rate is about 1.5 times of R22, the exhaust flow rate increases and the resistance increases. Generally speaking, the heat exchange capacity of the condenser is 20%-30% larger than that of R22.

3. The saturation pressure of R404A and R22 at the same temperature is different, so the action mechanism of R404A thermal expansion valve is different from that of R22. At the same time, due to the R404A refrigerant and lubricants on the seal material solubility is different, the expansion valve sealing material should be changed accordingly, so the choice of thermal expansion valve should be used in the R404A special expansion valve.

4. Since the saturation pressure of R404A is higher than R22, the design pressure of pressure vessel in the system should be changed to ensure safety. Such as the reservoir and gas-liquid separator. At the same time, the safety valve and fusible plug settings installed on the system fittings should also be changed. As the gas density of R404A is about 50% larger than R22 under the same exhaust volume, the pipe diameter should be larger than R22 when using R404A refrigerant for piping design.

5. For the same compressor, the current of R404A is larger than R22, so the wire diameter of AC contactor, thermal relay and cable of compressor should be adjusted. For system protection, the high pressure pressure switch setting is adjusted from 2.45MPa to 2.7MPa.

6. because the saturation pressure of 404A is different from R22, the gas tightness test pressure should be higher than R22. meanwhile, the vacuum of the system should be higher than R22 and the water content should be lower than R22. the refrigerant should be charged with liquid type to prevent the change of R404A group state.

7. R404A is a non-azeotropic mixture, the concentration of the components of the non-azeotropic mixture changes with temperature and pressure, which brings certain difficulties to the production, commissioning and maintenance of the refrigeration system, and also has a certain impact on the heat transfer performance of the system, especially when the refrigerant leaks, the system refrigerant needs to be emptied and replaced, so as to ensure the ratio of the mixed components, and to achieve the design Refrigeration effect, otherwise it will be worse and worse.

8. Because the R404A refrigerant and lubricant itself is very soluble with water, so the system requirements for moisture and residue, cleanliness, etc. are increased compared with R22 refrigerant, R404A system moisture control and impurity control is a more important index, the corresponding filtering device in the system should be changed.

------------------------------------------------

[ Company Information ]

Chengdu Henbin Refrigeration Co., Ltd

Add: 88 North Xingle Rd, Xindu District 610000, Chengdu, Sichuan, China

Tel : +86-28-83085054

Fax : +86-28-83085055

Email: info@henbincool.com   

Website: http://www.henbincool.com/

[ Contact ]

Kathy Zhang

WhatsApp(WeChat): +86 189 8059 4786

Email: kathy@henbincool.com

Allie Han

WhatsApp(WeChat): +86 137 0803 3050

Email: allie@henbincool.com

[ Follow Us ]

Instagram: https://www.instagram.com/henbinrefrigeration/

LinkedIn:https://www.linkedin.com/company/chengdu-henbin-refrigerant-technology-co-ltd/

YouTube: https://www.youtube.com/channel/UCegvGxhwM-kvvTinoQw6uXQ