How to Select Roots Vacuum Pump Unit
How to choose Roots Vacuum Unit and what should we pay attention to? How to choose a good Roots vacuum machine? However, the choice of Roots vacuum machine to choose the right pressure, otherwise the enterprise will not be able to use, the following by the of share knowledge about Roots vacuum machine:
The selection of pumping speed ratio between Roots pump and front pump is very important for the vacuum unit of Roots pump. Because the compression ratio of the pineapple pump is very limited. This compression ratio determines the capacity of the front pump, because the compression ratio is the inverse ratio of the pumping speed. Generally, the compression ratio is chosen in the range of 2 to 10. In addition, consideration should be given to the requirement of pre-sampling time. Vacuum equipment is used as auxiliary equipment in various mechanical equipment. If the normal working time is much longer than pre-pumping time, a smaller front pump can be selected (compression ratio can be larger), and if the vacuum suffocation is larger, and the requirement of rapid pre-pumping, a larger front pump will be used. Sometimes in order to better play the efficiency of the equipment, the unit is equipped with a larger pre-pumping pump in front, which is stopped after normal operation, and maintained with a smaller pre-pumping, so as to save power.
Roots Vacuum Unit
The limit pressure requirement of Roots vacuum pump unit must also be considered when choosing the front stage pump. For the high limit vacuum (1 *10-3 pa~1 *10-2 Pa pressure), two-stage rotary vane oil seal mechanical pump or two-stage sliding mechanical pump are generally selected as the front stage pump. The limit vacuum degree requires that a single-stage oil seal mechanical pump be selected as the front-stage pump between (1*10-2Pa~1*10-1Pa) and a reciprocating vacuum pump or a liquid ring vacuum pump be selected as the front-stage pump between 133 and 1333 PA.
When the reciprocating or liquid ring rough vacuum pump is selected as the front pump of Roots vacuum pump, the speed of the front pump is generally 1/2-1/4 of that of Roots vacuum pump, which can not be too large, otherwise the compression ratio will be too large, resulting in high exhaust temperature of Roots vacuum pump and can not work normally. When choosing the front-stage pump, it is also necessary to consider whether there is corrosive medium in the pumped gas and whether it contains condensable gas, whether it is large or small. If there are corrosive gases, oil-seal mechanical pumps can not be selected. Oil-seal mechanical pumps are not suitable for extracting gases containing a large amount of condensable steam. Otherwise, the sealing fluid will be quickly emulsified. When extracting gases containing a small amount of condensable steam, oil-seal mechanical pumps with gas-ballast devices must also be used as the front-stage pumps.
In order to obtain high pumping rate at low inlet pressure (1-100pa), a Roots vacuum pump can be used as the first stage pump of another Roots vacuum pump to form a three-stage or four-stage unit. At this time, the pumping speed ratio of Roots vacuum pump is generally between 2 and 5.