In this article, we discuss four flammable and explosive refrigerants.
As we all know, Refrigerants can pose numerous hazards, Including as it related to toxicity. flammability asphyxiation and / or physical hazards. The American Society of Heating, Refrigerating and air conditioning Engineering (ASHRAE) standard 34 classifies refrigerants by Hazard Based on Toxicity and Flammability.
The following table provides an overview of refrigerant safety group classification.
There are four classes of flammability: 1, 2L, 2, or 3.
- Class 1 is for refrigerants that, when tested, show no flame propagation at 140°F (60°C) and 14.7 psi (101.3 kPa).
- Class 2 is for refrigerants that, when tested, exhibit flame propagation at 140°F (60°C) and 14.7 psi (101.3 kPa), has a heat of combustion less than 19,000 kJ/kg (8,174 British thermal units BTU/lb), and have a lower flammability limit (LFL) greater than 0.10 kg/m3.
- Class 3 is for refrigerants that, when tested, exhibit flame propagation at 140°F (60°C) and 14.7 psi (101.3 kPa) and that either has a heat of combustion of 19,000 kJ/kg (8,174 BTU/lb) or greater or an LFL of 0.10 kg/m3 or lower.
1. R32 refrigerant
R32, also known as difluoromethane and carbon difluoride, is colorless, odorless, and has a safety level of A2. A Freon substitute with excellent thermodynamic properties, R32 has a low boiling point, low vapor pressure, a large refrigeration coefficient, no ozone depletion, a small greenhouse effect coefficient, and is flammable and explosive. The combustion limit in the air is 15%~31% and will burn and explode when it meets open flame.
R32 has a lower viscosity coefficient and higher thermal conductivity. Although R32 has many advantages, R32 is a flammable and explosive refrigerant, and air conditioning installation and maintenance is already dangerous work, now add the uncertainty of R32, safety issues have to be considered. Installation and welding of R32 refrigeration equipment should be vacuumed.
2. R290 refrigerant
A new environmentally friendly refrigerant, R290 (propane), is mainly used in central air conditioners, heat pump air conditioners, domestic air conditioners, and other small refrigeration equipment. A new environmentally friendly refrigerant, R290 (propane), is mainly used in central air conditioners, heat pump air conditioners, domestic air conditioners, and other mini cooling systems. Since R290 is a hydrocarbon refrigerant with an ODP value of 0 and a GWP value of less than 20, it has obvious environmental advantages over common refrigerants. As follows:
- R22 has an ozone layer destruction of 0.055 and a global warming factor of 1700
- R404a has 0 damage to the ozone layer and a global warming coefficient of 4540
- R410a has 0 damage to the ozone layer and a global warming factor of 2340
- R134a with 0 damage to the ozone layer and a global warming factor of 1600
- R290 has an ozone layer depletion of 0 and a global warming factor of 3
Additionally, R290 refrigerant has a high latent heat of evaporation, excellent fluidity, and high efficiency. However, Due to its flammable and explosive properties, the filling volume is limited and the safety level is A3. When using R290 refrigerant grade, it should be evacuated and open flames are forbidden because air (oxygen) mixed with R290 can form explosive mixtures, which are at risk of igniting upon contact with a heat source or open flame.
3. R600a refrigerant
R600a isobutane, a new type of hydrocarbon refrigerant with excellent performance, is made from natural ingredients, is non-toxic, has no greenhouse effect and no damage to the ozone layer, and is eco-friendly. Among its characteristics are high latent heat of evaporation, strong cooling capacity, good fluidity, low delivery pressure, low power consumption, and slow return of load temperature. Compatible with various compressor lubricants. Under its own pressure, it is a colorless transparent liquid and colorless transparent gas. R600a is mainly used to replace R12 refrigerant, and now it is mostly used in household refrigerator equipment.
R600a refrigerant has an explosive limit volume of 1.9%~8.4%, safety level A3. When mixed with air, it can form explosive mixtures, and it produces combustion and explosive reactions when it meets heat sources and opens fire, and it reacts violently with oxidizers; its vapor is heavier than air and can spread over a considerable distance at lower levels, and it will catch fire and reignite when it meets fire sources.
4. R717 (ammonia) refrigerant
The last refrigerant we will discuss is R717 (ammonia).
In comparison with the above three types of refrigerators, ammonia is the most dangerous; it is classified as a toxic medium, level 2.
If people are exposed to ammonia vapor for half an hour when its concentration reaches 0.5*0.6% by volume, they can become poisoned.
As a result of the nature of ammonia, it is necessary to regulate the operation and maintenance of ammonia systems, we should pay more attention.
Ammonia is a medium-temperature refrigerant, pure ammonia has no adverse effect on lubricating oil, but when there is moisture, it will reduce the lubricating effect of refrigeration oil, copper, and copper alloy are not used for piping and valve parts in the ammonia refrigeration system.
As a refrigerant, ammonia has the following advantages: easy obtaining, low cost, moderate pressure, large unit refrigeration capacity, high exothermic coefficient, almost insoluble in oil, low resistance to flow, easy to detect when leaking, no destruction of the ozone layer, no greenhouse effect.
Its disadvantages are: irritating odor, toxic, can burn and explode, and have a corrosive effect on copper and copper alloy.
When the volume of ammonia vapor in the air reaches 0.5-0.6% can cause an explosion. Therefore, the concentration of ammonia in the air of the room should not exceed 0.02mg / L. Ammonia is flammable at room temperature, the explosion limit is 16% to 25%, the most easily ignited concentration is 17%, the maximum explosion pressure is 22.5%.
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