Air compressor marking methods and technical parameters

Air compressor four basic labeling methods

1, the use of motor horsepower to indicate:

This is not feasible in the early air compressor technology, but with the continuous development of technology, it is now to use the same motor, but also because of the level of pressure, compressor manufacturers and models of different sizes, leaving the actual The amount of air flow compressor row day difference. Therefore, it is the most irresponsible practice to list only the motor horsepower in the catalog.

2, the use of gas volume (Inltvolume) to indicate:

This representation is usually set on the inlet side with an orificemeter and is currently used only to indicate the size of the centrifugal compressor. The unit used CFM, which although more accurate than the previous method, but not because of internal losses, it is still higher than the actual amount of gas.

3, using the piston displacement (Pistondispiacent) to represent:

Since this is the compressor design information, simply multiply the cylinder size of the number of revolutions, so this information is the most readily available, but also used by many manufacturers marked. There is no certain relationship between this theoretical value and the actual air volume, depending on the manufacturer's technical capabilities.

This method is the use of aperture side flow meter side of the export side of the set, as accurate and thus become the world's main criteria used to determine the actual amount of compressor output, such as 150, ASME, JIs and so on. However, in some Japanese factory catalogs, F.A.D. is used. To mark, but raised NoinaloaPaoity, usually understandable statement is: The F.A.D. Not true, but just a design value. Regrettably, standards are the same thing. Whether it is done or not is the same thing. Therefore, the credibility of the standard should be greatly reduced unless the standard on which the black and white printed on the original catalog is based.

The actual air output under different operating conditions The actual air output refers to the amount of air taken into account at the outlet of the compressor (after the aftercooler) taking into account all the losses, usually expressed in Free Air Delivery. The so-called free air volume refers to the volume of air compressed by the compressor to the air inlet free air conditions (temperature, pressure, humidity, etc.) to represent. Therefore, even if the same test standard is used, it will be expressed differently depending on the free air taken

1, the normal condition (Noralcondition):

Method of representation: Nm: / Inin (or indicate the air condition used in the side test) Air condition: 760mmHg, 0 ℃, ORH, volume index: 1.00;

2, the standard condition (standardcondition):

Indication: SCFM (or indicate the condition of the gas used in the test) refers to the air condition: lbar, 200C, ORH Volume Index: 1.05 (approx)

3, the actual situation (Actualcondition):

Air flow: 14.4Psi, 35 ℃, 6ORH Volume index: 1.20 (about) The same output, as long as the use of different air conditions, Can make the figure bigger 20.

The actual value of actual air output (FAD) measured under different pressures is related to the reference air condition and also to the test under what pressure. For example, 55KW Roots blower measured at 0.5bar when the actual air output is about ground, 40M5 / min, 55kw micro-oil screw compressor at 8bar when the actual output of about 9.1m5 / min side, The actual air output measured at 13 bar is about 6.8 m 5 / min.

Therefore, when comparing the actual output of compressors of different brands with the same power, it is necessary to consider the most pressure of the test flow at the same time. There is no strict theoretical calculation formula to convert, but there is a recognized empirical formula can be used as a reference.

For oil-injected screw compressors, maintaining the same actual air output at increased pressure requires increased rotor speed while consuming as much as 67 motor power. For a fully oil-free screw compressor, you need to increase the power consumption by about 10. For example, suppose a 55kw micro-oil screw machine A in the bottom of 7bar actual air flow rate of 9.5m5 / min, the other 55kw micro-oil screw machine B in the bottom of the 8bar actual air flow was 9.1m5 / min, Is A high efficiency or B high efficiency? According to the above empirical formula, A to remain in the 8bal 9.54m5 / min air output unchanged, you need to increase the power consumption of more than 6, that is, 55kwtimes; 1.06 = 58.3kw The specific energy of the two are:

A: 58.3 kwdivide; 9.5 m 5 / min = 6.11 kw / (m 5 / min)

B: 55kwdivide; 9.1m5 / min = 6.04kw / (m5 / min) (6.11-6.04) divide: 6.04times:

100 = 1.16: This means that B compressor efficiency of 1.16.

Air Compressor Motor Power Air Compressor efficiency is related to the actual compressor air output and the power consumed by the motor. The actual amount of air due to the side of the test method and that different methods in the numerical differences. The same is true when looking at the compressor's motor power. At the same time, the compressor efficiency is also related to the service factor of the motor, the motor efficiency and the like.

1, Service factor (ServiceFactor) The air compressor motor power refers to the nominal power of the motor or rated power, but this does not mean that the actual power consumed by the motor. For domestic manufacturers in Europe and China, the motor power consumption is generally less than the nominal power rating plate, while the US manufacturers are accustomed to using a smaller motor, the service factor greater than 1.25; and at full load , The output of the motor can exceed the nameplate 15, such as the motor labeled looHP, the actual output of which makes the actual power consumption of the motor must be less than the rated power on the motor nameplate, the old rules were broken. Therefore, in general, for the same horsepower compressor, the European brand of air volume data than the US brand of air volume data for the above reasons. Now some European brand manufacturers have begun to laugh at the country's practice.

2, the specific pressure shaft horsepower People often used (specificenergy) a unit of output to measure the compressor power consumption efficiency, where the power consumption is said that the specific pressure shaft horsepower, meaning the compressor outlet pressure reaches a certain pressure point Time. Compressor spindle power consumed. Due to different manufacturers selected pressure points are not the same, which marked shaft horsepower is not the same as the efficiency of air compressor air compressor efficiency to consider its side-test method, said the state, the side of the test pressure point, the actual power consumption , But also consider the motor efficiency, because shaft horsepower is only a happy part of the motor, the user to pay the electricity cost is calculated according to the pleasant power, the efficiency of the compressor can not but consider the efficiency of the motor. Without an understanding of the standards used by each manufacturer in labeling compressors and motors, it would be almost pointless to compare the efficiency of their catalogs with their catalogs. In fact, even knowing all the details of the manufacturing plants is very difficult to compare, because the relationship between different standards is difficult to determine. Therefore, comparisons based on the information provided on the catalog are for reference only.