1 Piston air compressor

1.1 The air compressor is to be fitted with a pressure gauge which may have the functions of water tightness, shock resistance and backlight as required.

1.2 A safety valve is to be set after each stage of compression. The set pressure of the inter-stage safety valve is not to be more than 1.2 times the maximum working pressure of the stage. The set pressure of the safety valve at the final stage is not to be more than 1.1 times the rated discharge pressure.

1.3 A safety valve is to be set when the volume of the crankcase of air compressor exceeds 0.6 m3. The total flow area of the safety valve is to be more than 0.07 times the volume of crankcase.

1.4 In the cooling system of water-cooled air compressor, anti-rust and anti-corrosion measures are to be taken for the components contacting cooling water and a cooling water drainage channel is to be provided for cylinder water drainage.

1.5 The water-cooled air compressor is to be fitted with coolers. The multi-stage water-cooled air compressor is to be fitted with an intermediate cooler and an after-cooler. A cooling water safety valve or bursting disc and a drain cock or valve is to be fitted to the cooler. The outlet of the after-cooler of air compressor is to be fitted with a small fusible plug or alarm device which is to be fused or give an alarm when the air temperature exceeds 121°C under the working pressure.

1.6 The air compressor is to be fitted with unloading mechanism. In the mode of automatic control, it is to be manually operated.

1.7 The air compressor is to be fitted with a liquid-air separator (the air-cooled air compressor with a nominal volume flow of not more than 24 m3/h may not be fitted).

1.8 The air suction port of air compressor is to be fitted with an air filter.

1.9 The exposed moving parts of air compressor are to be provided with a shield mainly made of metal wire meshes or steel plates.

1.10 For the high-temperature exhaust pipe of air compressor, a thermal baffle or other appropriate heat insulation measures are to be taken to ensure the temperature of possible human contact part does not exceed 60°C.

1.11 The air compressor may have the following automatic control functions with automatic control devices sensitive and reliable:

(1) Automatic start/stop

(2) Automatic unloading

(3) Automatic discharge

(4) Monitoring of air, oil and water pressure

(5) Monitoring of air, oil and water temperature

1.12 The exhaust air temperature of every stage of air compressor at the rated discharge pressure is to be not more than 200°C. The temperature of the air into the air receiver is not to exceed the water inlet temperature plus 30°C for the water-cooled air compressor, and not to exceed the ambient temperature plus 40°C for the air-cooled air compressor.

1.13 The temperature of lubricating oil in the crankcase of air compressor is not to exceed 70°C for the water-cooled air compressor, and not to exceed 80°C for the air-cooled air compressor.

1.14 When the air compressor operates under the rated condition, for medium and low pressure air compressors (rated discharge pressure ≤ 4.0 MPa), the vibration intensity is not to be more than 18 mm/s; for high pressure air compressors (rated discharge pressure ≥ 15 MPa), the vibration intensity is not to be more than 28 mm/s; for the air compressor with a rated discharge pressure between 4 ~ 15 MPa, the vibration intensity is not to be more than 25 mm/s.

1.15 The parts under air pressure (e.g. cylinder, piston, cylinder liner, cooler, liquid-air separator, air pipe, etc.) are to be able to be subjected to hydrostatic tests under a pressure 1.5 times the maximum working pressure. The hydrostatic test pressure of water channel and water chamber is to be generally 0.50 MPa. The connections between parts under air pressure are not allowed to have leakage under the maximum working pressure.

2 Screw air compressor

2.1 The air compressor is to be fitted with a pressure gauge. The pressure gauge may have the function of water resistance or backlight as required.

2.2 A sensitive and reliable safety valve is to be set after each stage of compression of air compressor. The set pressure of inter-stage safety valve is not to be more than 1.2 times the maximum working pressure of the stage. The set pressure of safety valve at the final stage is not to be more than 1.1 times the rated discharge pressure.

2.3 The air compressor is to be fitted with an automatic flow control device so as to meet the requirements of the users on flow variation.

2.4 The air suction port of air compressor is to be fitted with an air filter.

2.5 An oil-air separator is to be set at the exhaust side of air compressor.

2.6 The pressure-bearing parts such as the housing, exhaust end cover, exhaust chamber and oil pump housing of air compressor are to be subjected to hydrostatic tests under a pressure 1.5 times the maximum working pressure.

2.7 The speed-increasing gearbox of air compressor, if any, is to be subjected to a kerosene leakage test.

2.8 The rotor of air compressor is to be subjected to a dynamic balance test.

2.9 The vibration intensity of air compressor is not to be more than 5.1 mm/s.

2.10 For the high-temperature exhaust pipe of air compressor, a thermal baffle or other appropriate heat insulation measures are to be taken to ensure the temperature of possible human contact part does not exceed 60°C.

2.11 The air compressor may have the following automatic control functions with automatic control devices sensitive and reliable:

(1) Automatic start/stop

(2) Automatic unloading

(3) Automatic discharge

(4) Monitoring of air, oil and water pressure

(5) Monitoring of air, oil and water temperature

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