Views: 0 Author: Site Editor Publish Time: 2022-12-29 Origin: Site
R32, also known as difluoromethane, carbon difluorocarbon, colorless, tasteless, safety grade A2. R32 is a kind of freon substitute
with excellent thermodynamic performance. It has the characteristics of low boiling point, low steam pressure and pressure, large
refrigeration coefficient, zero ozone depletion value, small greenhouse effect coefficient, combustible and explosive. The
combustion limit in the air is 15% ~ 31%, and the open flame will burn and explode.
R32 has a lower viscosity and a higher thermal conductivity. Although R32 has many advantages, R32 is a combustible and
explosive refrigerant. Installation and maintenance of air conditioners is a dangerous work. Now, with the uncertainty of R32,
safety issues have to be considered. Install and weld the R32 refrigeration equipment to be vacuumed.
R290 (propane), is a new type of environment-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. Compared with common refrigerants, R290 has obvious environmental protection
advantages, as shown in the following figure :
The destruction of ozone layer by R22 refrigerant is 0.055 and the global warming coefficient is 1700 ;
R404a refrigerant destroys ozone layer 0 and global warming coefficient 4540 ;
The destruction of ozone layer by R410A refrigerant is 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 ;
The destruction of the ozone layer by the R290 refrigerant is 0, and the global warming coefficient is 3.
In addition, R290 refrigerant has the characteristics of greater evaporation latent heat, good fluidity and energy saving. However,
due to its combustible and explosive characteristics, the amount of irrigation is limited, and the safety level is A3. Use the R290
refrigerant stage to vacuum, do not open flame, because air (oxygen) mixing can form explosive mixture, heat source and open
flame risk combustion explosion.
R600a isobutane is a new type of hydrocarbon refrigerant with excellent performance. It is taken from natural components, does
not damage the ozone layer, has no greenhouse effect and is environmentally friendly. It is characterized by large evaporation
latent heat and strong cooling capacity; Good fluidity, low conveying pressure, low power consumption, slow load temperature
recovery. Compatible with various compressor oils. It is a colorless gas at room temperature and a colorless transparent liquid at
its own pressure. R600a is mainly used to replace R12 refrigerant and is now used in household refrigerator equipment.
R600a refrigerant explosive limit volume of 1.9%-8.4%, safety grade A3, mixing with air can form explosive mixture, encounter heat
source and open flame has the risk of combustion explosion, contact with oxidant violent reaction, its vapor is heavier than air, It
can spread at a lower point to a considerable distance, and it will catch fire and rekindle when it comes to the source of fire.
Finally, let's talk about R717 (ammonia) refrigerant, ammonia is more dangerous than the above three refrigerators, it belongs to
toxic medium, toxic level 2.
When the volume concentration of ammonia steam 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 operated and maintained in a standard manner, and
the refrigerant should pay attention to the use. Prior to our refrigeration encyclopedia public number has issued ammonia
refrigerant use specifications and precautions training manual, interested friends can read.
Ammonia belongs to medium temperature refrigerant, pure ammonia has no adverse effect on lubricating oil, but when there is
moisture, the lubrication of refrigerant oil will be reduced, in ammonia refrigeration system to pipeline and valve parts are not
copper and copper alloy. The advantages of ammonia as a refrigerant are: Easy to obtain, low price, moderate pressure, large unit
refrigeration capacity, high heat release coefficient, almost insoluble in oil, small flow resistance, easy to find when leaking, no
destruction of ozone layer, no greenhouse effect. The disadvantages are: It has irritating odor, toxic, combustible and explosive,
and corrodes copper and copper alloys.
Explosion can be caused when the volume of ammonia vapor in the air reaches 0.5-0.6%. Therefore, the concentration of ammonia
in the air in the equipment room should not exceed 0.02 mg/L. Ammonia is a kind of combustible gas at room temperature. The
explosion limit is 16% ~ 25%, the most easily ignited concentration is 17%, and the concentration when the maximum explosion
pressure is 22.5%.
