Surprising! So Much Knowledge About Air Receiver Tanks!

The primary function of an air receiver tank within a compressed air system is to stabilize air supply. Compressed air precipitates condensate inside the tank, regulating air pressure fluctuations caused by unbalanced air consumption of pneumatic equipment, 

improving pressure stability for end users. In addition, it reserves a certain volume of compressed air. When the air compressor breaks down, this reserve air can be used for emergency handling of pneumatic equipment and control systems.

Selection of Air Receiver Tanks
1. Pressure Selection

Based on withstand pressure, air receiver tanks are categorized into high-pressure, low-pressure and atmospheric-pressure types. 

The rated pressure of the selected tank shall be greater than or equal to the discharge pressure of the air compressor. For example, if the compressor operates at 8 bar, the tank pressure rating shall not be lower than 8 bar.

2. Volume Selection

The recommended volume of the air receiver tank ranges from 0.3 to 0.5 times the air compressor’s free air delivery. If site conditions permit, 

a larger-volume tank is preferred, which can store more compressed air and realize better preliminary water removal.

Example: An air compressor with free air delivery of 1 m³/min and working pressure of 8 bar. According to the selection formula, 

the tank volume should be between 0.3 m³ and 0.5 m³ (no less than 1/5 to 1/3 of the compressor displacement). A 0.2 m³ or 0.3 m³ tank is recommended. 

If higher air demand will be added in the future, the tank volume can be appropriately enlarged, such as 0.5 m³, 0.6 m³ or 1 m³.

3. Material Selection

By material, air receiver tanks can be divided into carbon steel tanks, low-alloy steel tanks and stainless steel tanks. Matching with air compressors, refrigerated dryers, 

filters and other equipment, they form the compressed air station as power source for industrial production.

Most industries adopt carbon steel and low-alloy steel tanks. Low-alloy steel tanks feature higher yield strength and toughness than carbon steel tanks, 

with a relatively higher price. Stainless steel tanks are mainly applied in industries requiring comprehensive performance (corrosion resistance & formability), 

including food processing, pharmaceutical, chemical, microelectronics and other precision equipment manufacturing sectors. Users can make selections according to actual working conditions.

Service Life of Air Receiver Tanks

Air receiver tanks belong to special pressure equipment. Manufacturers provide a recommended service life, generally 10 years. 

This does not mean tanks cannot be used after 10 years. If the tank exceeds 10 years of age but passes annual inspection by the market supervision bureau, it can remain in service. 

However, tanks failing inspection before reaching 10 years must be decommissioned. Continued service is determined strictly based on official inspection results. 

It is recommended to purchase air receiver tanks from formal well-known large brands.

Generally speaking, tanks with volume ≤ 1 m³ and design pressure ≤ 10 bar (including 10 bar) are classified as simple pressure vessels, exempt from national periodic inspection. 

The nameplate and product quality certificate will mark it as a simple pressure vessel. It enjoys inspection exemption within the valid period of 7 years and does not require registration. 

Safety accessories shall be inspected in accordance with local market supervision bureau regulations.

Installation must be undertaken by qualified contractors.
Air receiver tanks with volume above 1 m³ and pressure above 16 bar must be submitted for inspection at the local quality inspection institute, and a special equipment usage registration certificate must be obtained.
Connection Ports of Air Receiver Tanks
Two types of inlet and outlet connections are available: threaded connection and flange connection.

Threaded Connection: Threaded ports adopt screw thread structure, suitable for small-diameter connections, marked with Rp (internal cylindrical pipe thread). For instance, 

Rp1/2 means the tank is equipped with Rp internal thread; Rp2 stands for 2-inch internal thread. Common sizes: 1.5 inch, 2 inch.

Flange Connection: Flanges are specified by DN (Nominal Diameter). DN50 refers to nominal diameter of 50 mm. During assembly, pipelines are fixed to flange plates, 

with flange gaskets placed in between, and two flanges are fastened together by bolts. Flange connections are easy to disassemble and deliver better sealing performance than threads. 

Large-diameter connections generally adopt flange type. Standard flange sizes include DN80, DN100, DN125, DN150; non-standard customized sizes such as DN200 and DN300 are also available.

Not all tank specifications come with both threaded and flange ports. There is no fixed rule for selection; the decision mainly depends on the interface size of the air compressor.
Operation of Safety Valves on Air Receiver Tanks

As a vital accessory fitted on air receiver tanks, safety valves play a critical role for the whole system. Due to its special characteristics, adjustment must be completed by professional operators, 

and pre-operation inspection is mandatory. Follow the steps below during inspection:

(1) Shut off the air supply source first;

(2) Supply water and start equipment for test operation. Observe the pressure gauge. If the safety valve fails to open at the set pressure, further adjustment is required. 

Adjust the bolt gradually to achieve proper opening pressure. Repeat inspection and adjustment cycles to confirm the safety valve can open reliably.

Air receiver tanks must be operated strictly in accordance with specifications. Safety valves and pressure gauges shall be installed correctly and submitted for annual inspection 

(subject to local market supervision bureau requirements). If production cannot be shut down, a spare set shall be prepared. No chances should be taken. Safety shall always be the top priority.

Operation Precautions for Air Receiver Tanks
The air receiver tank is prohibited from overpressure and overtemperature. Operators shall ensure the tank works under normal operating conditions.
Open flame is forbidden around the tank or on the vessel surface. Do not use open flame to check the tank interior. No maintenance, hammering or impact on the tank shell is allowed when the tank is under pressure.

For oil-injected air compressors, compressed air must go through oil removal and water treatment. The oil content, 

water vapor content, solid particle size and concentration grade of compressed air shall comply with Appendix A of GB/T3277-91 Quality Classes of Compressed Air for General Use before entering the receiver tank.

Contact between lubricating oil and air inside compressors may lead to carbon deposition, spontaneous combustion and oil explosion under excessive temperature (refer to GB10892-89). 

The temperature of compressed air entering the tank must not exceed the tank’s design temperature. To avoid excessive discharge temperature, the air compressor’s overtemperature shutdown device shall be inspected regularly; 

heat transfer surfaces (filters, separators, coolers) require periodic inspection and cleaning.

For oil-injected compressors, regularly inspect all pipelines, vessels (air receiver tanks) and accessories between the compressor discharge port and the point where compressed air temperature drops to 80°C. 

All carbon deposits (including carbon buildup on compressor cylinder heads) must be thoroughly removed.

Operation and maintenance of air compressors and air receiver tanks must strictly comply with Safety Rules and Operating Procedures for Stationary Air Compressors, 

Safety Requirements for Positive Displacement Air Compressors and Safety Requirements for Process Compressors.

Failure to comply with the above operation requirements and warnings by tank users may result in tank failure and severe explosion accidents. All users must bear this in mind!