OUTLINE of the creation of drains
When normal air is compressed, drains are always concentrated. When air is compressed, the temperature rises to approx. 180°C and all of the moisture from the original volume of air is compressed into a smaller area. When this compressed air is cooled down as it passes through pipes on its way to a pneumatic device, any moisture that cannot be contained in suspension will form water droplets. These droplets trap tiny amounts of dust in the air, lubrication oil and metal powder that is created by the compressors' operation. The result is a concentration of drains. Unless these drains are eliminated, the problems that occur with precision pneumatic devices cannot be eliminated.
<Examples> For example, compress air at 20°C temperature with 65% relative humidity using a 30 HP compressor at a pressure of 7 kgf/cm2 (approx. 180°C). Operate a device using this compressed air for 6 hours. If all of the compressed air is returned to ambient temperature (20°C), 14 liters of moisture will be generated.
Volume of drains generated per hour by a compressor
Intake air temperature 30°CXX
Intake air humidity 80%XX
Pressure 7kgf/cm2XX
capacity (kw)
Liquid volume (L/h)
0.2 0.03
0.4 0.07
0.75 0.12
1.5 0.25
2.2 0.36
3.7 0.61
5.5 0.91
capacity (kw)
Liquid volume (L/h)
7.5 1.2
11 1.8
15 2.5
18 4.1
22 5.0
27 6.1
37 8.4
capacity (kw)
Liquid volume (L/h)
55 12.5
75 17.0
110 22.3
125 27.9
150 33.5
225 50.2
300 66.9
capacity (kw)
Liquid volume (L/h)
400 89.2
500 111.5
600 133.8
700 156.1
800 178.4
900 200.7
1000 223.0
Other major drain components besides moisture
From the atmosphere Dust, fine metal powder, textile fibers, powdered cement, etc.
Sulfur dioxide, hydrogen sulfide
From the work area Lubrication oil from compressors.
Rust, delaminated substrates
metal powder, powder from deteriorating seals and other parts in the compressor.
Disintegrating filter element material, etc.
Drains and their influence on equipment
Moisture Faulty insulation, clog and shorten life span of valves, freeze.
Oil and rust Elongation of rubber valves, shortened life span of equipment, pollution, unacceptable spray paint results, reduced airway size in equipment.
Carbon Seized valves, fire or explosion from accumulations of carbon, reduced airway size in equipment, shortened life span of equipment.
Dust Clogged filters, faulty seals
Problems in facilities and equipment caused by drains
Inside pipes Decreased flow rate and increased pressure drop due to the formation of rust, corroded pipes and tanks, and accumulation of rust.
Negative influence on equipment Faster clogging of filters.
Faulty operation of valves, cause of air leaks.
Malfunctions due to insufficient flow rate, increased pressure drop.
Damage from water hammering.
Faulty lubrication and malfunctions in parts.