Air compressor labeling method

In the 21st century, the air compressor market is fiercely competitive. Consumers often choose machine quality and price as part of their purchasing standards. Therefore, a variety of marking methods commonly used in the market as a description, to contribute to the protection of consumer sports.

One. Four basic logo methods:

1. Use motor horsepower to indicate:

This is not feasible in the early days of air compressor technology, but with the continuous development of technology, even though the same motor is used now, but also because of the pressure level, air compressor manufacturers and models of different sizes, Air compressor row of the amount of wind there is a world of difference. Therefore, it is the most irresponsible practice to list only the motor horsepower in the catalog.

2. Use piston displacement (Piston displacement) to indicate:

Because this is the air compressor design information, only the cylinder size multiplied by the number of revolutions, so this information is the easiest to get, but also for many manufacturers used to mark. There is no certain relationship between this theoretical value and the actual air volume, depending on the manufacturer's technical capabilities.

3. Use the Inlet volume to indicate:

This representation is usually measured on the inlet side by an Orifice meter and is currently used only to indicate the size of the centrifugal compressor. The unit used by the ICFM, although more accurate than the previous two methods, but not included in the internal loss, it is still higher than the actual amount of gas.

4. Use Free air delivery to indicate:

This method is the use of aperture meter measured at the exit side, as accurate and thus become the world's main standard used to determine the actual air compressor output, such as ISO, ASME, JIS, etc. However, in some Japanese manufacturers directory, Use FAD to mark, but add Nominal capacity, it is generally understandable that: This FAD is not true, but only a design value.

It is a pity that standards are one thing and whether or not they are done is not the same thing. Therefore, the credibility of the original catalog will be greatly reduced unless it is based on the standard written on black and white on the original catalog.

Second, under different conditions showed the actual amount of air:

The actual air output refers to the air volume measured at the exit of the air compressor (after the aftercooler) taking all the losses into consideration, and is usually expressed as 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 standards are used, the numbers shown will differ by more than 20% from the "free air" taken. The following are some common free-air conditions.

1. Normal Condition (Normal Condition):

Said method: Nm3 / min (or indicate the test used in the gas situation)

Indicated air condition: 760 mmHg, 0 0C, 0% RH

Volume index: 1.00

2. Standard Condition (Standard Condition):

Said: SCFM (or indicate the test used in the gas situation)

Air condition indicated: 1 bar, 20 0C, 0% RH

Volume index: 1.05 (about)

3. Actual Condition (Actual Condition):

Representation: ACFM, ICFM (or indicate the gas condition used in the test)

Indicated air conditions: 14.4 psi, 35 0C, 60% RH

Volume index: 1.20 (about)

The same amount of gas, as long as the use of different air conditions, can increase the figure 20%.

Third, under different pressures tested out the actual amount of air:

The actual value of the air volume (FAD) is related to the reference air condition and also to the test under what pressure.

For example, a 55 kW Lurtz blower measured an actual air output of about 40 m3 / min at 0.5 barg and a 55 kW micro-oil screw compressor measured an actual air output at 8 barg of about 9.1 m3 / min, whereas the actual air output measured at 13 barg is about 6.8 m3 / min.

Thus comparing the actual power with different brands of different brands of air compressor output, to consider the pressure of the test flow. There is no strict theoretical calculation formula to convert, but there is a recognized empirical formula can be used as a reference.

For the injection screw air compressor, if the pressure is still rising to maintain the same actual air output, you need to increase the rotor speed, while consuming 6 ~ 7% of the motor power. For a completely oil-free screw air compressor, you need to increase the power consumption by about 10%.

For example, suppose the actual air output of a 55 kW micro-oil screw machine A measured at 7 barg is 9.54 m3 / min and that of another 55 kW micro-oil screw machine B measured at 8 bar is 9.1 m3 / min, whether A high efficiency or B high efficiency?

According to the empirical formula above, if the output of A remains at 9.54 m3 / min at 8 barg, the power consumption of more than 6% needs to be increased, that is, the specific energy of 55 kW × 1.06 = 58.3 kW is respectively:

A: 58.3kW ÷ 9.54m3 / min = 6.11kW / (m3 / min)

B: 55 kW / 9.1 m3 / min = 6.04 kW / (m3 / min)

(6.11-6.04) ÷ 6.04 × 100% = 1.16%

This means that B air compressor efficiency of 1.16% high.

Four air compressor motor power

Air compressor efficiency and the actual air compressor output and the power consumed by the motor. The actual amount of air due to different test methods and that there are significant differences in value. The same is true when examining the motor power of an air compressor. At the same time, the efficiency of the air compressor is also related to the service factor of the motor, the efficiency of the motor and the like.

1. Specific pressure shaft horsepower

People often use specific energy (Specific Energy) - the unit output of the power consumption to measure the efficiency of air compressor, where the power consumption is said that the specific pressure shaft horsepower, meaning the air compressor outlet pressure reaches a certain pressure point, air pressure Spindle power consumption. Due to different manufacturers selected pressure points are not the same, which marked the shaft horsepower is not the same.

Service factor

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 actual motor power consumption is generally less than the nominal power rating, while the US manufacturers are accustomed to using a smaller motor, its service factor is larger, such as 1.25, and at full load , The motor output can exceed the nameplate 15%, such as the motor identified as 100HP, the actual output may exceed 115HP. This made the old rule that "the actual power consumption of the motor must be less than the rated power on the motor's nameplate."

Therefore, in general, for the same horsepower air 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 the United States.

V. Compressor efficiency

As mentioned above, consider the efficiency of air compressor to consider the test method, said the state, the test pressure points, the actual power consumption, etc., but also consider the motor efficiency, because the shaft horsepower is only the output part of the motor, the user pays electricity according to the input power Calculated, the efficiency of air compressor can not but consider the efficiency of the motor.

In this way, it would be almost pointless to compare the efficiency of each manufacturer with the information on his catalog, without understanding the standards each manufacturer uses to identify its compressors and motors. 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 can only be "referenced."