Common marking methods for air compressors
In the 21st century, the air compressor market is highly competitive. When consumers choose products, they often consider the quality and price of the machine.
（1）. Four basic marking methods
Since this is the design data of the air compressor, it is only necessary to multiply the size of the cylinder by the number of revolutions, so this data z* is easy to obtain, and Grid is included in the purchase criteria. Therefore, we will explain the various labeling methods commonly used in the market, and do our part to protect consumers.
1. Use motor horsepower to express
This was feasible when the air compressor technology was not developed in the early days, but with the continuous development of technology, even if the same motor is used now,
Due to the pressure level, the air compressor manufacturer and the size of the model, the amount of air exhausted by the actual air compressor is very different.
Therefore, only motor horsepower is indicated on the catalog, which is an irresponsible practice of z*.
2. Use Piston displacement to indicate
Used by many manufacturers to mark. There is no certain relationship between this theoretical value and the actual gas output. It depends on the manufacturer’s technical capabilities.
It depends on the force.
3. Use Inlet volume to indicate
This method of expression is usually measured by an Orifice meter on the side of the air inlet, and is currently only used to indicate the size of a centrifugal air compressor. The unit used is I CFM, which is more accurate than the previous two methods, but because the internal loss is not accounted for, it is still higher than the actual gas output.
4. Use free air delivery to express
This method uses an aperture flow meter to measure on the outlet side. Because of its accuracy, it has become the world's main standard for measuring the actual air output of an air compressor, such as ISO, AS ME, J IS, etc. However, in some Japanese manufacturers catalogs In, using FAD to mark but adding Nominal capacity, it is usually
understandable that this FAD is not true, but just a design value.
It is a pity that it is one thing to have a standard, and it is another thing to do it or not. Therefore, unless the standard is stated in black on the original catalog, its credibility will be greatly compromised.
（2）. The actual air output shown in the table below under different working conditions The actual air output refers to the air output measured at the
outlet of the air compressor (after the after-cooler) after considering all losses, usually with the free air output (Free Air Delivery).
The so-called free air volume means that the volume of air compressed by the compressor is expressed by the free air condition (temperature, pressure, humidity, etc.) of the air inlet.
Therefore, even if the same test standard is used, the displayed number will differ by more than 20% due to the different "free air" used. The following are several commonly used free air conditions.
1. Normal Condition:
Representation method: Nm 3/min (or indicate the gas inlet condition used in the test)
Refers to the air condition: 760mmHg, 00C, 0%RH
Volume index: 1.00
2. Standard Condition:
Representation method: SCFM (or indicate the air intake condition used in the test)
Refers to the air condition: 1bar, 200C, 0%RH
Volume index: 1.05 (approximately)
3. Actual Condition:
Representation method: ACFM, I CFM (or indicate the gas inlet condition used in the test)
Referred air condition: 14.4psi, 350C, 60%RH
Volume index: 1.20 (approximately)
With the same air output, as long as you use different air conditions, you can increase the number by 20%.
（3）. The actual air volume tested under different pressures
The actual air output (FAD) value is related to the reference air condition, and also related to the test pressure.
