Why is there water in the air compressor exhaust?

We all know that the "humidity" of the air refers to the dryness of the air, that is, the air contains water.

The air compressor does not produce water, but only acts as a "porter" of water in the process of compressing air. When the air in the natural state is compressed or cooled, it will tend to a saturated state until it is supersaturated, and the water in the air will be precipitated, changing from a gaseous state to a liquid state, and water is thus produced.

With compressed air systems, compression is the purpose, and cooling begins after compression and continues throughout.

When the air compressor is working, because the gas is compressed to release a lot of heat, the internal temperature of the compressor head is very high (about 100 ℃). The water in the inhaled natural air will form water vapor during the compression process of the air compressor and be discharged with the compressed air.

Generally, an air cooler is equipped in the air compressor unit to force the cooling of the compressed air that is ready to be discharged from the air compressor. The purpose is to use the cooling and condensation effect to remove a part of the water in the compressed air.

This is still under the condition that the cooling and drainage function of the air compressor itself is sound, otherwise, the compressed air and water will flow to the back-end pipeline together.

Even if the drainage function of the air compressor body is normal and there is no liquid water at the outlet of the air compressor, the discharged compressed air is still saturated. With just a little cooling, liquid water will still condense out of the compressed air.

In the compressed air system, there are various pipes, air storage tanks, filters, etc. connected to the outlet of the air compressor. The temperature of these objects is lower than the discharged compressed air (generally, the exhaust temperature of the air compressor is the ambient temperature. 10°C or more), which will inevitably condense a large amount of water.

Especially in the gas storage tank, when the compressed air passes through the gas storage tank, the high-speed airflow hits the wall of the gas storage tank to cause a confluence, the temperature in the gas storage tank drops rapidly, and a large amount of water vapor liquefies to form condensed water.

How to remove water from air compressor exhaust?

It is impossible and unnecessary to completely remove water from compressed air, we just need to achieve the dryness we want.

Usually for most general compressed air applications, such as driving cylinders, purging, air tools, etc., as long as the gas end does not contain liquid water at the current ambient temperature.

For some occasions with higher requirements, such as spraying, textiles, electronics, food and medicine, etc., each has its own requirements for the moisture in the compressed air.

There are roughly three levels of moisture removal in air compressor exhaust:

1. Air compressor body

The air compressor body should be equipped with a gas-water separation device, and try to remove a part of the liquid water in the air compressor body. Some small or some simple air compressors do not have this function. If this device is missing or fails, the moisture removal from the compressed air will have to be undertaken by the back-end dewatering equipment, possibly resulting in overload.

2. Air compressor pipeline and daily life

The air storage tank, filter, and the end of the pipeline on the air compressor pipeline are several important drainage points. In particular, the gas storage tank is the most convenient and critical.

At present, in addition to manual ball valve device drainage, automatic drainage device has also been widely used. But whether manual or automatic drainage, daily operation and maintenance and inspection are still the most important.

3. Special water removal equipment

The special water removal equipment for the compressed air system mainly includes: pipeline gas-water separation device, refrigerated dryer, adsorption dryer, precision filter, etc., which can be reasonably configured according to the gas demand.

When does the air compressor usually drain?

Adjust according to the specific use environment and working conditions. Generally, if the manual ball valve is used for the drain outlet, it needs to discharge the condensed water regularly. If the automatic drainer is installed, it is necessary to regularly check the self-draining function.

The frequency of drainage or inspection mainly depends on the humidity of the intake air (season and environment, the humidity is higher and more frequent) and the outlet temperature of the air compressor (higher temperature requires more frequent).