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Mechanical sealing skills

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One. Basic knowledge of mechanical seals:
1. The basic concept of mechanical seal:
Mechanical seal refers to a device for preventing fluid leakage caused by at least one pair of end faces perpendicular to the axis of rotation under the effect of fluid pressure and compensating for the elastic force (or magnetic force) of the tissue and the cooperation of the auxiliary seal. 1. The auxiliary seal is a metal bellows called a bellows mechanical seal.
2. The composition of the mechanical seal:
There are four main types of components.a. Primary seal: moving ring and static ring. b. Auxiliary seal: seal ring. c. Pressing parts: spring, push ring.d. Transmission parts: magazine holder and key or fixing screw 2. The machine seal operation should focus on the problem:
1. Matters needing attention when equipment
a. It is necessary to pay great attention to prevent equipment errors in the equipment. (1) The tightening gland should be carried out after the coupling is aligned; the bolts should be evenly supported; the end face of the gland should be prevented from deflecting; the points should be viewed with the feeler gauge; Not more than 0. 05 mm.
(2) Check the cooperation gap between the gland and the outer diameter of the shaft or bushing (ie concentricity); the circumference should be uniform; the tolerance of each point with the feeler gauge is not more than 0. 01 mm.
b. The amount of tension spring tightening should be carried out according to the rules; no excessive or too small appearance is allowed; the demand error is 2.000 mm. The end face specific pressure is added over the assembly; the other end face wears. If it is too small, the specific pressure will be insufficient to seal. effect.
c. After the moving ring device, ensure that it can move sensitively on the shaft; after pressing the moving ring to the spring, it should be able to rebound back.
2. Matters needing attention when disassembling
a. Be careful when disassembling the mechanical seal; do not use the hand hammer and the flat shovel; prevent damage to the sealing element. Do a pair of wire hooks; extend into the gap of the drive seat in the direction of self-supporting profit; pull out the sealing device. When the scale is not disassembled; it should be cleaned and then disassembled.
b. If the mechanical seal is used at both ends of the pump; in the equipment; take care of each other during the disassembly; prevent the stretch.
c. Mechanical seals that have been worked; any condition in which the gland is loose to cause the seal to move; then the dynamic ring parts need to be replaced; it should not be used continuously from the head. Because of the turbulence after the conflict; The sealing of the touch surface is very simple and damaged.
three. Machine seal normal work and protection problems:
1. Preparation before starting and matters needing attention
a. View all mechanical seals; and whether the subordinate equipment and pipeline equipment can be complete; can match the skill needs.
b. Static pressure test before mechanical seal launch; check whether the mechanical seal can have leakage appearance. If there are more leaks; the cause should be found to be eliminated. If it is still invalid, it should be disassembled to view and de novo equipment. Usually static pressure test pressure 2 ~3 kg / cm 2 .
c. According to the pump, turn to the car; check whether it is light and even. If the car is struggling or not moving, you should check whether the equipment scale is faulty; whether the equipment is reasonable.
2. Equipment and outage
a. Before starting, the liquid in the sealed chamber should be filled. When transporting the condensed medium, use the steam to heat the sealed chamber to melt the medium. It is necessary to drive the vehicle before starting; to prevent the soft ring from breaking.
b. Regarding the mechanical seal using the pump external sealing oil system; the oil sealing system should be started first. After the parking, the oil sealing system is finally stopped.
c. After the hot oil pump is stopped, the cooling water of the sealing oil chamber and the end face seal cannot be stopped immediately; the oil temperature of the end face seal should be reduced to below 80 degrees; the cooling water can be stopped; the sealing parts can be prevented from being damaged.
3. jobs
a. If there is a slight leakage after the pump is launched, it should be investigated for a period of time. If it is connected for 4 hours, the amount of leakage is still not reduced. 蛴ν1 eyebrows.
b. The operating pressure of the pump should be stable; the pressure should not be more than 1 kg/cm 2 .
c. The pump is in operation; it should prevent the appearance of convulsions; prevent the formation of sealing surface conflicts and seal damage.
d. The sealing condition should be checked frequently. During work; when the leakage exceeds the standard; the heavy oil is not more than 5 drops/min; the light oil is not more than 10/min; if there is no improvement trend within 2-3 days, the pump should be stopped. Sealing equipment.

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