subject: The Static Type Of Mechanical Seal [print this page] Special medium of Mechanical Seal Selection
1. Labile media
The labile media, such as some hydrocarbons, when the temperature 175 , and the air in contact with carbonation; temperatures continue to rise, when the temperature 260 , the temperature and touch, they will aggregate and cracking, the formation of sticky wax Web results and solid plastic.
Avoid this approach is:
(1) using metal bellows seal,
(2) Simultaneous use of hot steam quench and to ensure continuous steam rushed to mechanical seal end surface.
(3) high temperature media, when parking should be steam quench.
2. Room temperature is a solid medium
The room temperature is a solid medium, such as heavy hydrocarbons, caprolactam, sulfur, etc., may consider taking the following measures:
(1) with heating jacket.
(2) The static type of mechanical seal, while rapid cooling by thermal steam, and to ensure continuous steam rushed to pump seal end surface.
(3) should also be heat pump sealed seat.
(4) The drive should take measures to ensure that medium to work in the liquid.
3. Easy to medium crystal
For the temperature drop, easy crystallization of the medium, should ensure that the pump seal between the inside temperature is always above the saturation temperature, but should also take the steam quench.
For the temperature drop, easy to mold, and re-heating, can melt the media, such as carbamates and caprolactam and other media, the solution is to use stationary metal bellows, while heat pump sealing gland, to take the steam quench and set a Anti-Coke baffle to prevent coking.
4. Incompatible media
Incompatible media means there are two kinds of media or more mutually insoluble components, such as oil and water.
May consider the following measures:
(1) Heavy type with driving elements.
(2) matching materials should be used on tungsten carbide, or SiC bronze on CW. In the face of such media as the liquid film formed between the unstable, resulting in dynamic and static force ring is also highly volatile.
5. Polymerization of liquid trade
No matter what kind of trade for the polymerization of liquid, are required to take the following measures:
(1) to take measures to prevent the occurrence of polymerization.
(2) General should take a double seal with pressure bellows.
(3) The narrow seal faces (knife-like sealing surface of sealing well, of course, overly fragile).
(4) matching materials should be used hard materials such as SiC on SiC, or SiC TC ring on the stationary ring.
6. ABS serous
John Crane to solve a transportation company in South Korea when the ABS pump problems slurry very typical.
The original is as follows:
(1) ABS slurry and air, water and heat will aggregate.
(2) intermittent operation of the pump, stopping when the air will enter the pump.
(3) the use of a single seal, the seal between the slurry and easy to gather.
John Crane measures are:
(1) the use of rubber bellows pressurized double seal, water as liquid separation, to ensure the purity of ABS slurry.
(2) Matching materials for the narrow-side face of SiC static TC Central.
(3) to increase the inside of the axial seal gap.
Actual usage as follows:
(1) a small amount of polymer will occur, but because there are large inter-face contact stress, be able to grind out the grout sealing surface, so leakage does not increase.
(2) South Korea for a device with the pump, the seal life from 2 to 4 weeks to 1 year.
