R134a refrigerant (tetrafluoroethane) is a colorless gas with a boiling point of -29 °C. Due to r134a refrigerant properties, it is used in air conditioners, chillers, refrigeration equipment, polymer production, medicine, and cosmetology. It is also known as:
- HFC R134a;
- Refrigerant R134-a;
- Refrigerant 134a;
- Freon ™ 134a;
- HFC 134a.
We will tell you about the characteristics of HFC-134, physical and chemical properties, application. You will learn about the peculiarities of the use and operation of equipment on R134a. We present tables of boiling point, the pressure of refrigerant r134-a, properties of saturated vapor, and liquid under different conditions.
History of appearance
In 1987, the Montreal Protocol was signed, according to which ozone-depleting freons were gradually phased out of use. The refrigerant r134a (HFC 134a) is designed to replace R12. It has zero ozone depletion potential.
R-134 gas has become widespread due to its low cost and global warming potential. It has 8.39 times less influence on the greenhouse effect than R12 freon. But when it is replaced, it must be disposed of.
Technical characteristics of r134a refrigerant
|Boiling point at one atmosphere||–26.06 °C|
|Critical temperature||101.08 °C|
|Critical pressure||4060.3 kPa|
|Critical density||515.3 kg/m³|
|Critical volume||0.00194 m³/kg|
|Freezing point (°C)||-103|
|Density of liquid at 25 °C (kg/m³)||1.206|
|Density of liquid at 0 °C (kg/m³)||1.293|
|Density of saturated vapor at boiling point||5.28 kg/m³|
|Steam pressure (25 °C) at 1 bar||6.657|
|Steam pressure (0 °C) at 1 bar||2.92|
|Heat of vaporization at boiling point||217.2 kJ/kg|
|Specific heat of liquid at 25 °C and 1 atm||1.44 kJ/kg|
|Specific heat of liquid at 0 °C and 1 atm||0.85 kJ/kg|
|Liquid viscosity at 25 ° С (Pa s)||0.202|
|Steam viscosity at 25 °C (Pa s)||0.012|
|Surface pressure at 25 °C (mN/m)||8.09|
|Solubility in water at 25 °C and 1.013 bar (wt%)||0.15|
|Water solubility in R134a at 25 °C and 1.013 bar||0.11 (wt%)|
|Volumetric cooling capacity at -25 °C||1192.11 k/m³|
|Heat capacity of steam at 25 °C and 1 atm (kJ/kg K)||0.852|
|Thermal conductivity of liquid at 25 °C (W/m K)||0.0824|
|Thermal conductivity of steam at 25 °C (W/m K)||0.0145|
|ODP (Ozone Depletion Potential)||0|
|GWP (Global Warming Potential)||1430|
Freon R134a is a one-component gas. If leaked, does not require full refilling. Equipment operating on this refrigerant can be refilled without loss of efficiency. This is a big advantage over air conditioning and refrigeration systems at R410a, R407c, R404. Freon R134a is also used as a component of all effective substitutes for R22 refrigerant.
R134a refrigerant is non-toxic, it is used in the production of inhalers, aerosols, capsules for freezing injuries. Subject to the basic rules of safety and use, negative effects on human health can be avoided.
The molar mass of tetrafluoroethane is 102.03 g/mol, that of air is 29 g/mol. In the event of a leak, the gas goes down and accumulates at floor level in basements. This property of HFC-134a prevents it from entering the lungs under normal conditions.
Freon 134 is not compatible with mineral oils. When they come into contact, foaming, oil ingress into the system, and deposition on its walls are possible. This leads to the formation of tight spots and blockages. Equipment with this refrigerant must be filled with PAG or POE synthetic oil.
At the moment, this gas is not prohibited, but everything may change. more stringent requirements are imposed on refrigerants every year. Due to its strong influence on the greenhouse effect, restrictions may be imposed on its use. Therefore, analogs and substitutes for R134a are being actively developed.
Temperature, pressure, density, surface tension R134a
This table shows the following values:
- P – pressure in kPa;
- ρ – density in kg/m3;
- σ – surface tension in mN/m.
|t, ℃||P, vapor||ρ, liquid||ρ, vapor||σ|
Table of pressure, the boiling point of freon r134a
|t, °C||P, barg||t, °C||P, barg||t, °C||P, barg|
Replacing R12 with R134a
Replacing R-12 refrigerant gas with R-134a is a logical step. The production and use of the former are decreasing, it is becoming more expensive. When changing refrigerant, consider the following:
- When using r-134a instead of r-12, completely change the oil. Freon R12 works on mineral, R134a – on synthetic.
- The cooling capacity of the equipment may decrease or increase by 5-10%.
- R134a refrigerant molecules are smaller and more likely to leak through joints and seals. You need to monitor the state of the system. If necessary, replace weak nodes.
- Some synthetic oils contain aggressive additives. It is necessary to test their compatibility with sealing materials and system components.
- It is necessary to replace the filter drier, adsorbent, install additional, or increase its amount. Filters designed for R12 will not cope with the task when working with R134a.
- When replacing R-12 with R-134a, it is necessary to replace or adjust the expansion valve (thermostatic valve, thermostat). It is also worth calibrating the pressure gauges for the appropriate pressure.
Comparison of R134a and R12 characteristics
|P, kPa||t, °C||t, °C||P, kPa||t, °C||t, °C|
Freon r134a and human health
Despite its low toxicity, careless handling of HFC R134a can lead to side effects of varying severity.
The permitted concentration of refrigerant 134a in the air is 0.1% or 1000 ppm. If the refrigerant is inhaled with an air of such concentration for 12 hours, there will be no negative effect on human health.
Inhalation of air with a high content of r134a refrigerant can lead to depression of the nervous and cardiovascular systems with side effects:
- Decreased mental alertness;
- Confusion and loss of consciousness;
- Loss of coordination;
- Rapid pulse;
- Pressure drops.
When the concentration of freon in the air is more than 7.5% or 75,000 ppm, the cardiovascular system becomes sensitive to adrenaline. The normal rhythm of the heart is disrupted. Together with emotional stress and worries, this can lead to a heart attack and death.
Eyes & Skin
At room temperature, freon vapors do not affect the eyes and skin. If R134a enters the liquid phase, there is a frostbite claim. If this happens, it is necessary to rinse the damaged areas with warm water and consult a doctor.
Freon r-134a is not explosive in its normal state. Mixed with air, it ignites from an open fire or high temperature at +100 Celsius degrees and normal atmospheric pressure. The risk of ignition increases with:
- Increasing pressure;
- An increase in the concentration of oxygen in the air;
- The temperature rises.
- If there is a risk of liquid phase leakage or splashing, protect your eyes and exposed skin;
- When carrying out repairs and maintenance of systems with a large amount of freon r134a, it is necessary to check the premises for leaks with a gas analyzer;
- Technical premises associated with the operation of refrigeration systems must be equipped with powerful forced ventilation;
- If a slightly sweet smell appears while working with the refrigerant, immediately leave the room and ventilate it.
- Do not work with the r134-a near open flames or high-temperature sources. Do not mix gas with air or oxygen for any purpose.