Mechanical Seals for Zero LeakageWritten by Thomas Yoon
A centrifugal water pump contains a few basic components as follows:1) The housing for containing water. 2) The impeller attached to a rotating shaft that moves water. 3) The coupling that transmits rotating action of a motor (or other prime movers) to pump shaft. 4) The seal between housing and rotating shaft. 5) The bearings for ensuring that shaft turns smoothly. 6) The inlet and outlet ports for channeling water flow through pump. In order for a pump to work, pump impeller must generate pressures inside pump housing. The seal between housing and rotating shaft plays a critical role in making pump work. One of most common ways of sealing a rotating pump shaft is by using mechanical seals. The 3 components of a mechanical seal are: 1) The rotating component that moves together with rotating shaft. 2) The stationary component that is fixed to pump housing. 3) The spring that presses rotating component onto stationary component axially. Rotating Component This is a ring, usually consisting of 2 types of materials - a soft carbon piece with a highly polished axial surface, and a rubber material or o-ring that is able to grip shaft for sealing against water leak through shaft surface.
| | Simple But Powerful Centrifugal ChillersWritten by Thomas Yoon
Centrifugal chillers are used for cooling large buildings in a centralized air conditioning system. There are other types of chillers using screw compressors and reciprocating compressors. These are usually smaller in size. Today's topic is about centrifugal chillers - ultimate choice for any air conditioning installations higher than 500 RT (refrigeration tons)Basically, centrifugal chillers use centrifugal fans to move refrigerant within chiller circuit. As with any refrigeration circuit, there must be a compressor, a condenser, an expansion device, and evaporator. In case of centrifugal chiller, fan is compressor. Rotating at very high speeds, it is capable of pressurizing refrigerant gas so as to increase its temperature. Because pressure is so dependent on efficiency of impeller of compressor, impeller is very carefully designed to match system. The clearances between impeller and housing at mouth ring (impeller suction) are made very small so as to reduce leaks back to discharge. Usually inlet vanes that throttle gas control flow of gas, and thus chiller load. The expansion of liquid to gas is usually made through a fixed orifice.
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