Air storage tanks use the sealing and pressure resistance of the tank body to store compressed air or other gases, playing the role of buffering, storing and stabilizing pressure. In compressed air systems, a gas storage tank is usually installed between the air compressor and the gas-consuming equipment, and the gas is released through the outlet valve.
An automatic drain valve is a device used to drain liquid or gas, usually installed at the bottom of a pipe or pipeline, and automatically opens or closes according to changes in liquid or pressure. Since the gas may contain moisture and impurities, these substances accumulate in the gas tank and cause certain corrosion and impact on the equipment. Therefore, in order to ensure the quality of gas and the life of equipment, it is necessary to use an automatic drain valve to discharge moisture and impurities in the gas tank in time.
There are several important reasons for adding an automatic drain valve to an air tank:
I. Prevention of tank corrosion
- Corrosion generation mechanism: the air contains a certain amount of water vapor, when compressed air is stored in the tank, with the change of environmental conditions, the water vapor will condense into liquid water when it is cold and settle at the bottom of the tank. At the same time, compressed air inevitably carries impurities such as dust and oil during the generation and transmission process. These impurities mix with water and create conditions for electrochemical corrosion.In the case of a gas storage tank made of metal (e.g. carbon steel), for example, iron atoms (Fe), as an active metal, lose electrons in an electrolyte solution (standing water) containing impurities and are converted to ferrous ions (Fe²⁺). Oxygen in the air gains electrons and reacts with water to form hydroxide ions (OH⁻). Ferrous ions combine with hydroxide ions to form ferrous hydroxide (Fe(OH)₂). Ferrous hydroxide is easily oxidized to iron hydroxide (Fe(OH)₃) in the air, and eventually decomposes to form rust ( Fe₂O₃·xH₂O). As time goes by, rust continues to accumulate, the wall thickness of the tank gradually becomes thinner, and the structural strength and pressure resistance decrease significantly.
- Function of automatic drain valve: The automatic drain valve is installed at the bottom of the gas tank. It can automatically open the drainage channel according to the set conditions, such as timing or the depth of water accumulation, and discharge the accumulated water and impurities out of the tank in time. By reducing the contact time between water and the tank body, the occurrence of electrochemical corrosion is effectively curbed, greatly extending the service life of the gas tank.
II. Ensuring the quality of compressed air
- Strict requirements for gas-using equipment: In modern industry, many gas-using equipment have extremely high requirements on the quality of compressed air. Even a trace amount of moisture may cause chip short circuits and oxidation during the delicate process of chip manufacturing, resulting in serious quality problems or even scrapping of the product. The same is true in the food processing industry. If the compressed air in pneumatic equipment used in food packaging and transportation contains moisture and impurities, it will directly contaminate food and violate food safety regulations. In the paint shop, moisture mixed into the compressed air used for painting will cause defects such as orange peel and bubbles to appear on the paint surface, seriously affecting the painting effect and product appearance.
- The key role of the automatic drain valve: The automatic drain valve ensures that the compressed air output from the gas tank meets high quality standards by continuously and accurately discharging moisture and impurities in the gas tank, meeting the strict requirements of various gas-using equipment, and providing a solid guarantee for the normal operation of the equipment and product quality.
III. Maintaining stable gas storage tank performance
- Ensure effective volume: As moisture and impurities continue to accumulate in the gas tank, they will occupy a certain amount of space, causing the effective volume of the gas tank to gradually decrease. For example, if a gas tank with a designed volume of (10m³) has (1m³) of water and impurities accumulated at the bottom, then the actual space available for storing compressed air is only (9m³), which undoubtedly weakens the buffering and storage capacity of the gas tank, and may not be able to provide sufficient compressed air during peak gas demand.
- Stable air pressure supply: The presence of water and impurities will also interfere with the flow characteristics of compressed air in the air tank, causing the pressure fluctuations in the air tank to increase during the air intake and outlet process, making it difficult to stably provide the required air pressure for the air-using equipment.
IV. Improve the reliability and life of gas-using equipment
- Reduce the occurrence of failures: When the gas equipment is exposed to compressed air containing moisture and impurities for a long time, various failures are very likely to occur. In pneumatic tools, moisture can easily cause the internal mechanical parts to rust and wear, resulting in reduced performance of the tool, poor operation or even complete damage. If the channels of key components such as solenoid valves and cylinders in the pneumatic control system are blocked by impurities, they will not be able to work normally, causing the entire control system to fail. The automatic drain valve provides clean, dry compressed air to air-consuming equipment, significantly reducing the probability of equipment failure.
- Extend equipment service life: Clean compressed air can effectively reduce the wear rate of internal parts of gas-using equipment and reduce the risk of corrosion. Taking the air jet loom in a textile factory as an example, dry compressed air can reduce the blockage and wear of the air jet nozzle, enabling it to operate stably for a long time, greatly extending the service life of the air jet nozzle and the entire loom.
