Four kinds of combustible and explosive refrigerants, you must know!

1. R32 refrigerant

R32, also known as difluoromethane, difluorocarbon, colorless, odorless, safety level A2. R32 is a substitute for freon with excellent thermodynamic properties, with low boiling point, low vapor pressure and pressure ratio, large refrigeration coefficient, zero ozone loss value, small greenhouse effect coefficient, flammable and explosive characteristics. The combustion limit in the air is 15% to 31%, and it will burn and explode in case of open fire.

R32 has a low viscosity coefficient and a high thermal conductivity. Although R32 has many advantages, R32 is a combustible and explosive refrigerant, air conditioning installation and maintenance is inherently dangerous work, and now coupled with the uncertainty of R32, safety issues have to be considered. Vacuum the R32 refrigeration unit for installation and welding.

2, R290 refrigerant

R290 (Propane) is a new type of environmentally friendly refrigerant, mainly used in central air conditioning, heat pump air conditioning, household air conditioning and other small refrigeration equipment. As a hydrocarbon refrigerant, R290 has an ODP value of 0 and a GWP value of less than 20, which has obvious environmental advantages over common refrigerants, as shown below:

The destruction of ozone layer by R22 refrigerant is 0.055, and the global warming coefficient is 1700.

The destruction of ozone layer by R404a refrigerant is 0, and the global warming coefficient is 4540;

R410A refrigerant destroys the ozone layer to 0, and the global warming coefficient is 2340;

The destruction of ozone layer by R134a refrigerant is 0, and the global warming coefficient is 1600;

R290 refrigerant damage to the ozone layer is 0, global warming factor is 3,

In addition, R290 refrigerant has the characteristics of greater latent heat of evaporation, good fluidity, energy saving and so on. However, due to its combustible and explosive characteristics, the perfusion volume is limited, and the safety level is A3. The use of R290 refrigerant grade to vacuum, no open fire, because the air (oxygen) mixture can form an explosive mixture, in the case of heat sources and open fire there is a risk of combustion explosion.

3. R600a refrigerant

R600a isobutane is a new type of hydrocarbon refrigerant with excellent performance, which is derived from natural ingredients, does not damage the ozone layer, has no greenhouse effect, and is green. It is characterized by large latent heat of evaporation and strong cooling capacity. Good flow performance, low transmission pressure, low power consumption, slow load temperature recovery. Compatible with various compressor lubricants. It is a colorless gas at room temperature and a colorless transparent liquid under its own pressure. R600a is mainly used to replace R12 refrigerant and is now used in household refrigerator equipment.

R600a refrigerant explosion limit volume is 1.9% ~ 8.4%, safety grade is A3, mixed with air can form an explosive mixture, in the case of heat source and open fire there is a risk of combustion explosion, contact with oxidant violent reaction, its vapor is heavier than air, can spread to a considerable distance at a lower place, the fire source will ignite back.

4, R717 (ammonia) refrigerant

Finally, let's talk about R717 (ammonia) refrigerant, ammonia is more dangerous than the above three chillers, it belongs to the toxic medium, toxicity level 2.

When the volume concentration of ammonia vapor in the air reaches 0.5-0.6%, people can be poisoned by staying in it for half an hour. The nature of ammonia determines that the ammonia system must be standardized operation and maintenance, and the refrigeration person should pay attention to it. Previously, our refrigeration encyclopedia public number has issued a training manual on the use of ammonia refrigerants and precautions, interested friends can read it.

Ammonia is a medium temperature refrigerant, pure ammonia has no adverse effect on lubricating oil, but when there is moisture, it will reduce the lubrication effect of frozen oil, and copper and copper alloy are not used in ammonia refrigeration system for pipelines and valves. The advantages of ammonia as a refrigerant are: easy to obtain, low price, moderate pressure, large unit cooling capacity, high heat release coefficient, almost insoluble in oil, small flow resistance, easy to find when leaking, does not destroy the ozone layer, no greenhouse effect. Its disadvantages are: pungent odor, toxic, can burn and explode, and have a corrosive effect on copper and copper alloys.

When the volume of ammonia vapor in the air reaches 0.5-0.6%, it can cause an explosion. Therefore, the ammonia concentration in the air in the equipment room must not exceed 0.02mg/L. Ammonia is a flammable gas at room temperature, the explosion limit is 16% ~ 25%, the most easily ignited concentration is 17%, and the concentration is 22.5% when the maximum explosion pressure is generated.