Normal Pressures For R22

We can use refrigerant temperature pressure charts to help us understand the relationship between R22 gas and its psig pressure at different temperatures. By looking at this chart, we can see that the pressure of R22 is 155.7 psig at 85deg F.

The pressure-temperature relationship plays a key role in mechanical refrigeration. For example, when R22 gas is compressed and cooled to the outdoor temperature (90deg F), it condenses into a liquid (look at the refrigerant temperature pressure chart).

High Pressure

R22 refrigerant has a number of normal pressures depending on the outdoor air temperature and indoor wet bulb temperature. You can use a temperature correction chart to determine these pressures.

In general, a R22 compressor operates with a high-side compressor pressure of about 260 psi. The low-side or suction line pressure will also vary from the manufacturer’s service chart.

When a technician installs or services an R-22 system, there are certain precautions that should be taken. For example, only use brazing materials rated to withstand these higher operating pressures.

It is also important to make sure the tubing connections are secure and properly installed. Moisture will cause problems, so proper evacuation and replacement of filter-driers are essential to the performance and life of an R-22 system.

Low Pressure

A low pressure system is an area of weather where a sudden drop in atmospheric pressure causes cloudy or rainy conditions. As it passes through a region, these systems often clear the way for cooler, drier air to be introduced into the area.

On a weather map, a low pressure center indicates a region where the pressure is measured to be lowest relative to its surroundings. In the northern hemisphere, winds flow counterclockwise around a low pressure center. In the southern hemisphere, they swirl clockwise.

Due to the Coriolis effect, rising motion in the vicinity of a low pressure center favors the development of clouds and precipitation. These clouds act to dampen diurnal temperature extremes as incoming shortwave solar radiation is reflected away by the cloud cover, causing lower daytime temperatures and warmer night-time minimums in all seasons.

In residential air conditioning, typical operating pressures of R22 refrigerant vary depending on a variety of factors including compressor motor size and design and the incoming air temperature. However, many manufacturers provide a temperature correction chart that enables service technicians to easily calculate the suction vacuum and output high-side pressures needed to operate the air conditioner properly.

Evaporator Temperature

When an evaporator uses refrigerant to absorb heat energy, it changes its state from liquid to vapour. This process is called a vapour compression cycle and is used in many systems.

As with other fluids, the pressure of R22 is linked to its temperature. This pressure-temperature relationship is what allows the vapour compression cycle to operate and achieve high efficiency.

This means that the temperature of a refrigerant increases with the increased internal pressure in a refrigerant cylinder. Unlike water, there is no safety valve to control this pressure.

Therefore, it is important to understand the pressure-temperature relationship when using a cylinder.

A common rule of thumb is that the suction pressure should be about the same as the outdoor air temperature in an R-22 system. While this is a good general guideline, it doesn’t work for every system. It’s best to refer to a temperature correction chart that gives you the actual ambient temperature along with the static or equalized refrigerant pressure.

Suction Temperature

The suction temperature of r22 is a function of the refrigerant pressure at the compressor suction. This can be measured using a refrigerant pressure gauge or the standard PT charts for r22.

Generally speaking, the normal suction pressures for R-22 are around 40 PSIG. This is a very general rule of thumb and it has no scientific basis other than it just tends to work out that way on properly functioning systems.

Another very common rule of thumb is that the suction line temperatures will be very close to the outdoor ambient temperature on an R-22 system running in heat mode. This is just a fluke and doesn’t work for an R-410A system, but it is a good guideline to use on a properly functioning R-22 system when the outdoor temperature is around 40 degrees.

The discharge line temperatures can also be very high, especially when a compressor is underoperating and suction pressures are low. These conditions can lead to discharge temperatures that accelerate oil decomposition.

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