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High Pressure Vacuum Pumps

The Vacuum or air pumps used with steam condensing plants are of four types: reciprocating piston, positive rotary displacement, hydro centrifugal, and steam jet. The earliest dry vacuum pumps were merely air compressors of the piston type which worked between a high vacuum and atmospheric pressure. These pumps receive saturated “air” at the pressure existing in the condenser and compress it to a pressure high enough to discharge it to the atmosphere. Some reciprocating pumps are arranged with a crank and flywheel and are known as rotative dry vacuum pumps. Leakage, defective jacket cooling, and re-expansion of the air in the clearance spaces make it difficult to maintain a vacuum of more than 26in. of mercury referred to a 30-in. barometer. Another disadvantage of the reciprocating air pump is the excessive size and the high cost when the pump is made for large capacity. Positive rotary displacement vacuum pumps are usually of vane type construction.

 

 

In the hydraulic air pump, also called hurling water pump, a rapidly rotating impeller continuously hurls thin sheets of water through suitable water passages into a Venturi shaped discharge cone where the high velocity water stream entrains the air from the condenser.
A volume of air is compressed between two successive sheets of water and carried into the discharge cone. This mixture of air and water then passes into an expanding diffuser cone, where energy of the high-velocity stream is converted into pressure to discharge the water and entrained air into the atmosphere. The hydraulic air pump requires more power than the reciprocating pump.
The stream jet air-ejector type of vacuum pump has practically supplanted other types of stream condensers when high vacuum are required and when large volumes of gases must be handled, because of its compactness, absence of moving parts, simplicity of operation, and high efficiency. The capacity varies with the steam pressure and the size and number of steam nozzles.

Water pump, Volute, turbine pump, axial flow units.

 

High pressure air Pump, vacuum pumps. .