Introduction To China Industrial Vacuum Pump

Introduction To China Industrial Vacuum Pump

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Introduction to vacuum pump
Vacuum pump provides sub-atmospheric pressure for a variety of industrial and scientific applications. Different technologies of pumps are used for industrial gripping and chucking, laboratory degassing, and purification in the fields of chemical and semiconductor processing. Typically, vacuum pumps are flow-rated according to the volume of air exhausted without a pressure differential across the pump. Motor power is a reference value used to characterize vacuum pump size.

Vacuum pump types
Vacuum pumps include mechanical type, high and ultrahigh vacuum type, and venturi jet type. A variety of mechanical compression/evacuation systems are used to produce low pressures; vacuum pumps typically operate most efficiently in the rough or medium vacuum range. Vacuum pumps are frequently used as a backing or preliminary pump for high-vacuum systems.
Mechanical types include both positive and non-positive displacement pumps. High and ultrahigh vacuum pumps are pumps that are efficient in the molecular flow regime and require a backing pump to operate effectively. At very low pressure or high vacuum levels, gases act like a collection of individual molecules and pump techniques that impart a preferential momentum, reduce the mean free path or trap molecules are employed. High vacuum pumps are utilized in thin film and semiconductor fabrication processes and on many types of analytical instruments. Venturi or fluid jet vacuum generators rely on a flow of compressed air, gas, or liquid as the "motive" fluid to pull or create a vacuum at a desired port. They contain no moving parts and require no other power than the compressed fluid.
Common configurations for vacuum pumps include individual vacuum pump, combination or multi-technology pump, and vacuum pump system or station. An integral backing pump is a high vacuum pump system that includes a mechanical, sorption, or other backing pump to provide preliminary vacuum level for the high vacuum stage of the pump.

Performance indexes of vacuum pump
(1) Vacuum degree
Vacuum degree is generally can be expressed by the following methods.
Vacuum degree can be expressed by absolute pressure P, the unit is kPa, Torr.
Vacuum degree can be expressed by relative pressure p , the unit is kPa, mmHg.
p (kPa)=101.32-p(kPa)
p ( mmHg)=760-p(Torr)
1 Torr=1 mmHg
(2) Exhaust speed
Exhaust speed refers to the gas volumeof a vacuum pump per unit time at its inlet under the suction state (i.e. volume flow rate of a vacuum pump at suction pressure and temperature), the unit is m /h or m /min. Exhaust speed of a vacuum pump is related to suction pressure. The lower the suction pressure is, the lower the exhaust speed is. When the ultimate vacuum is reached, the exhaust speed is zero.
(3) Ultimate vacuum
Ultimate vacuum refers to the minimum steady value of pressure reached by a vacuum pump while exhausting the air, also is known as maximum vacuum degree.
(4) Exhaust time
t=2.3 (V/S) lg (p1 / p2)
Where,
t exhaust time, min;
V -volume of the vacuum system, m;
S exhaust speed of vacuum pump, m / min;
p1 the initial pressure of vacuum system, Kpa;
p2 the final pressure of vacuum system, Kpa.

Estimate of air leakage from vacuum system
It is hoped that any vacuum system is completely gas tight so as to achieve the best application state. In fact, air always leaks into the vacuum system. The best way to know air leakage amount of the system is to measure by experiment. But for a new design or the occasion where experiment can not be conducted, air leakage of system can be obtained by estimated calculation.
(1) The leakage can be estimated based on the seal length of the connecting joint.
The estimated leakage based on the seal length of connecting joint
The seal quality of the connecting jointLeakage k / kg. (Hm)
Very good0.03
Good0.1
Normal0.2
(2) The leakage can be estimated based on volume of vacuum system.
The estimated leakage based on volume of vacuum system
Volume m0.11.035102550100200
Average air leakage
/kg.h0.10.50.51.0122436485108201030

Vacuum pump selection
Determine the vacuum degree:
The vacuum degree (absolute pressure) at pump suction inlet shall be determined based on vacuum degree of vacuum system and the pressure drop in inlet pipeline.
Determine the exhaust speed
Exhaust speed of vacuum system shall be determined according to the special calculation formula.
Convert the exhaust speed
The above-mentioned exhaust speed shall be converted into the exhaust speed under the conditions regulated in the sample book provided by the pump manufacturer.
Select the vacuum pump type
The type of vacuum pump can be determined based on the requirements for exhaust speed and vacuum degree.

About the Author:
China-ogpe.com (http://www.china-ogpe.com) is a professional B2B Website, which focus exclusively on providing you with detailed product and trade information in the field of oil, gas and petrochemical equipment made in China.



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