whatis a mechanical seal ?

Question

used in centrifugal pumps.

Answer 1

A mechanical seal, is a type of seal utilised in rotating equipment, such as pumps and compressors. When a pump operates, the liquid could leak out of the pump between the rotating shaft and the stationary pump casing. Since the shaft rotates, preventing this leakage can be difficult. Earlier pump models used mechanical packing to seal the shaft. Since WWII, mechanical seals have replaced packing in almost all applications.

A mechanical seal is an improvement on gland type sealing pumps.It is highly recommended when chemical/fluid handled is costly,hazardous,toxic and it is used to save marginal amount of power.In gland type pump there is always leakage through a gland housing(1 drop/sec) which goes to ETP which has treat it and hence load on ETP WHICH IS ALSO A LOSS of power.Basically there are two types of mechanical seal:balanced and unbalanced. Balanced seal are recommended in high pressure applications.
A mechanical seal is a device which helps join systems or mechanisms together by preventing leakage (e.g., in a plumbing system), containing pressure, or excluding contamination.
Please visit for detailed information:
http://www.mcnallyinstitute.com/02-html/2-10.html
(The function of a mechanical seal is to seal the opening where the shaft enters the pump, preventing fluid leakage.Originally mechanical seals were developed to overcome the negative issues affiliated with packed stuffing boxes. Simple mechanical seals offered an alternative to fluid leakage; none, least not detectable with the naked eye. They eliminated the need for a routine maintenance schedule as once properly selected and installed they would function without attention until the seal faces themselves wore out which could be years later, versus packing months. While initial cost to purchase a pump with a simple seal may have been higher their were no post installation costs and the return for this investment could be realized immediately with virtually zero product loss over the life of the seal.
(http://answers.yahoo.com/question/index?qid=20061123085445AAkeCmS)

Answer 2

The secondary sealing elements especially of the Primary seal (which moves to compensate the seal faces wear) can be a o-ring or wedge ring of Metallurgy ranging from rubber to Teflon, these secondary seals have dynamic relative movements with the shaft or shaft sleeve when the Mechanical Seal is in operation. This Micromovements results in Localized heat generation which softens the shaft or sleeve material and tends to wear them away. This wear is more in the softer seals than the sleeve itself. But during a seal overhaul the soft spares are replaced whereas the sleeve being a costlier one is not replaced unless the damage is more that could warrant replacement. So during the course of time this wear area develops a leakage path and hence you see the leak. Hope this answers you.

Answer 3

Mechanical Seals have become a standard for Refineries, Chemical plants, waste water plants, Ships, and other critical leakage control industries, as well as applications applicable to the everyday consumer including automobile water pumps, and swimming pool pumps. They offer exceptional leakage control, and have increasingly replaced braided packing. Usage of mechanical seals will only expand as environmental hazards in developing nations become larger issues and need to be addressed.

Answer 4

It is a seal that separates the motor housing from the wet end of the pump. It is installed behind the impeller. Since the impeller must be surrounded by water and is also connected to the motor (which cannot be wet), a mechanical seal is used to prevent water from leaking from the pump volute (were the impeller is located), down the motor shaft. It allows the motor shaft to rotate without leaking.

Answer 5

the seal that is palced mechanically, like some gasket to seal two parts together (eg head of the centrifugal pump)

Answer 6

it's a seal that is made when two mechanical or physical components seal an opening to create vacuum or pressure. As an example carbon vane compressors work when the carbon vane is spun and scrapes the outside of the cylinder under induced gravitational force to create pressure.

Answer 7

a device, or part if you will, which seperates two areas, such as the inside and outside of the pump, or the propulsion chamber from the intake. perhaps as simple as clever design with an ' o-ring' to allow for vibration and movement of the device ( pump )