There are three main reasons for the failure of mechanical seals添加时间:2017-01-07 10:58:00
(1) sealing surface open
In the repair of mechanical seals, 85% of the seal failure is not due to wear and tear, but before the wear has been leaking.
When the sealing cover is opened, the solid particles in the medium under the action of liquid pressure into the sealing surface, the sealing surface is closed, the solid particles embedded soft ring (usually the right ink ring) on the surface of it into a "wheel" will damage the hard surface.
Because the ring or rubber ring fastening on the shaft (sleeve), when moving, moving ring can not be fit, and the sealing surface and sealing surface of the open, closed backward into the sealing surface, made of solid particles in.
At the same time shaft (sleeve) with solid particles also exist between the influence of sliding and sliding parts, rubber ring or ring (the common faults of relative dynamic sealing point.). In addition, the media will be in the rubber ring and the shaft (sleeve) friction parts produced in the crystal, spring will have solid material, so that the sealing surface will open. Mechanical seal
(2) over heat
Because of the heat on the sealing surface, the temperature of the rubber ring should be lower than the design specification. The use of fluorine rubber and PTFE temperature is 216 DEG C, the use of NBR temperature is 162 DEG C, although they are able to withstand the high temperature, high heat but because the sealing surface is generated, so the rubber ring is dangerous to sulfide, eventually lose their elasticity and leakage. (cold zone)
Between the sealing surface but also because of heat induced crystallization of the media, such as carbon, caused by sliding parts stuck and sealing surface by condensation. And some of the polymer due to overheating and coking, some fluid due to overheating and loss of lubrication and even flash fire.
Overheating can change the state of the media, but also increase its corrosion rate. Due to the deformation of the metal parts, the cracking of the alloy surface, and the cracks of some coatings, the design should adopt a balanced mechanical seal to reduce the pressure to prevent overheating.
(3) super poor
Tolerance is correct, it is necessary for the installation of mechanical seal, shaft (sleeve) must have the appropriate surface roughness and the correct size, but the manufacturer provides little tolerance data, these data is key to the installer. (depend on experience and common sense)
The dimensional accuracy and the shape and position tolerance of mechanical seals must meet the requirements of drawings.