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How Can Mechanical Seal Technology Master The Essentials?
May 02, 2018

How can mechanical seal technology master the essentials?

1. The basic concept of mechanical seals:

The mechanical seal refers to a device for preventing fluid leakage that is constituted by at least a pair of end faces perpendicular to the rotation axis that are held against and combined with relative slip under the action of fluid pressure and compensation mechanism elastic force (or magnetic force) and auxiliary sealing. The auxiliary seal of the compensation ring is a metal bellows called a bellows mechanical seal.

2. The composition of mechanical seals:

There are mainly four types of components. a. Main seals: moving ring and stationary ring. b. Auxiliary seals: seals. c. compression parts: spring, push ring. d. Transmission: magazine holder and key or fixing screw

二. Mechanical seal work should pay attention to the problem:

1. Precautions during installation

a. Be very careful to avoid the installation deviation caused by the installation

(1) The tight packing should be done after the coupling is aligned. The bolts should be evenly supported to prevent deflection of the cover surface. Check the points with a feeler gauge with an error of no more than 0.05 mm.

(2) Check the clearance (ie, concentricity) between the gland and the outer diameter of the shaft or bushing. The circumference should be uniform. Check the tolerance of each point with the feeler gauge is not more than 0.01 mm.

b. The amount of spring compression must be carried out according to regulations. No excessive or small phenomenon is allowed. The required error is 2.00 mm. Over the General Assembly to increase the end face pressure, the other speed end wear. Too small will cause insufficient specific pressure and can not play a sealing role.

c. After the ring is installed, it can be moved flexibly on the shaft. After the ring is pressed against the spring, it should spring back automatically.

2. Precautions when removing

a. Be careful when disassembling the mechanical seal. Do not use the hand hammer and flat spade to avoid damage to the sealing element. A pair of wire hooks can be made, and the seal device can be pulled out by extending into the gap of the transmission seat in the direction of self-financing. If scaling does not remove, clean it and remove it.

b. If mechanical seals are used on both ends of the pump, take care of each other in the process of assembly and disassembly.

c. For a mechanical seal that has been operated, if the gland is loosened and the seal moves, the moving and stationary ring parts must be replaced and should not be used again. Because after this kind of turbulence, the original running track of the friction pair will change, and the sealing of the contact surface will be easily damaged.

III. Normal operation and maintenance issues of the mechanical seal:

1. Preparation and precautions before starting

a. Fully inspect the mechanical seal, and whether the attachment and pipeline installation is complete and meet the technical requirements.

b. Before the mechanical seal is started, perform a static pressure test to check whether the mechanical seal leaks. If there are more leaks, you should find out the reasons and try to eliminate them. If it is still invalid, it should be dismantled and reinstalled. General static pressure test pressure with 2 ~ 3 kg / square centimeter.

c. Press the pump to rotate the disc and check if it is light and even. If the bicycle is difficult or not moving, you should check whether the assembly size is wrong and whether the installation is reasonable.

2. Installation and outage

a. Keep the sealed chamber filled with liquid before starting. For conveying a solidified medium, steam is applied to heat the sealed chamber to melt the medium. Before start-up, it is necessary to start the car to prevent the soft ring from cracking due to sudden start-up.

b. For mechanical seals that use pump-outside oil seal systems, start the oil seal system first. Stop the oil seal system after parking.

c. After the thermal oil pump is stopped, the sealing water of the sealing cavity and the end face cannot be stopped immediately. The cooling water should not be stopped until the oil temperature drops below 80 degrees at the end face seal to avoid damaging the sealing parts.

3. Operation

a. If there is a slight leakage after starting the pump, observe for a while. If continuous operation for 4 hours does not reduce the leakage, pump inspection should be stopped.

b. The operating pressure of the pump should be stable and the pressure fluctuation should not exceed 1 kg/cm2.

c. When the pump is in operation, evacuation should be avoided so as to avoid dry friction and seal damage on the sealing surface.

d. Sealing conditions should be checked frequently. During operation, when the leakage exceeds the standard, the heavy oil is no more than 5 drops/minute, and the light oil is no more than 10/minute. If there is still no improvement in the trend within 2-3 days, the pump should be stopped to check the sealing device.

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