About Mechanical Seals
Sino-Holding Co.,Ltd  作者:admin  来源:本站  发表时间:4/2/2006  点击:41    Font size:Large  Small

The basic concept of mechanical seal:

Mechanical Seal is defined as at least one rotation axis perpendicular to face compensation mechanism in the fluid pressure and stretch (or magnetic) and the secondary seal under the action of the Post merged with the relative sliding to maintain, constitute a device to prevent fluid leakage. Elastic loading mechanism and the secondary seal is a metallic bellows mechanical seal which we call metal bellows seal. Sealed in the light, there are also used as an aid to sealing rubber bellows, rubber bellows stretch limited, generally need to meet the load supported by elastic springs.

Centrifugal pump mechanical seal consists of:
There are four main parts.
a. main components: dynamic ring and stationary ring.
b. secondary seals: seals (with O-shaped, X-shaped, U-type, wedge, rectangular flexible graphite, PTFE coated rubber O rings, etc.).
c. elastic compensation mechanism: spring, pushing ring.
d. transmission parts: elastic and key, or a variety of Kei seat screws.

Mechanical seal should pay attention to the problem:

1. Installation Notes

a. the installation to be very careful to avoid bias arising from the installation
(1) the gland coupling alignment should be carried out after the bolts should be evenly supported to prevent the gland face skewed, with a feeler check points, the error is not greater than 0.05 mm.
(2) Check the gland and the shaft or sleeve diameter with the gap (ie concentric), four weeks should be uniform, with a feeler points tolerance no more than 0.01 mm.
b. the amount of compression according to the provisions of the spring, allowed the phenomenon is too large or too small to require error 2.00 mm. Than the pressure may increase the end, the other face wear rate. Too small will cause less than the pressure seal and can not play a role.
c. ring installed, it will ring after the spring pressure should be able to automatically bounces back.

2. Disassembly Note

a. In the installation, carefully remove the mechanical seal is prohibited to use hand-hammer and flat blade, so as not to damage the sealing elements. If the scale demolition of no less than should be cleaned before demolition.
b. If the pump mechanical seal both ends, in the assembly, the demolition process to take care of each other, to prevent the other.
c. mechanical seal on the run-off, where a loose gland seal is moved to the situation, the static rings parts must be replaced, not re-tighten the continued use. Because loose track after the friction will be a change in the original operation, the contact surface of the seal is very easily damaged.

Normal operation and maintenance of mechanical seal problems:

1. Before the start of the preparatory work and notes

a. comprehensive inspection of multi-stage pump mechanical seals and ancillary equipment and piping installation is complete, compliance with technical requirements.
b. Hot water pump mechanical seal before the start of the static pressure test, check whether the mechanical seal leakage. If the leak more, should find out the reason for trying to eliminate. If still ineffective, should be demolished and re-check the installation. General static test pressure for 2 to 3 kg / square centimeter.
c. rotation by turning the pump, check whether the light evenly. Such as turning difficult or does not move when the assembly should check whether the size error, the installation is reasonable.

2. Installation and outage

a. shall remain sealed before the start of cavity filled with fluid. Solidification of the medium for transmission, the application will be sealed vapor chamber heat to medium melt. Start before turning to prevent a sudden start caused by soft ring fragmentation.
b. For use outside the seal oil system pump mechanical seal, seal oil system should be launched. After stopping the last stop the seal oil system.
c. heat pump can not immediately stop after the outage seal oil and seal chamber cooling water seal at the oil temperature should be reduced to below 80 degrees, it can stop the cooling water to avoid damage to the seal parts.

3. Operation

a. If the pump starts minor leakage should be observed for some time. 4 hours continuous operation, such as, leakage is still not reduced, they should check the pump stops.
b. the operation of the pump pressure should be stable, the pressure fluctuation is less than 1 kg / square centimeter.
c. pump in operation, should avoid taking the time to the phenomenon of dry friction in order to avoid sealing surface and seal damage.
d. Always check the seal condition. Operation, when the leakage exceeds the standard, heavy oil is not more than 5 drops / min, light oil is not more than 10 / min, still no signs of improvement, such as 2-3 days, you should check the pump stops bolt seals.


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