Water pump is to fire fighting what mechanical seal is to water pump! Improper seal will lead to leak. Let’s study the knowledge of water pump together!

Questions 41 - 50:

41.What are the main characteristic parameters of mechanical seal?

(1)Diameter of axle: The size of the mechanical seal is selected based on the strength requirements.

(2)Rotate speed: Same with the speed of pump;

(3)The average circle speed of the sealing surface: refer to the sealing surface of the circumference of the average diameter. The average linear velocity of the sealing surface has great influence on the heat and wear of the sealing surface.

(4)Face pressure: refer to contact pressure on the seal face. The sealing of face pressure should be controlled within a reasonable range, which will reduce seal performance when the face pressure is smaller and aggravate the heating and wear when the it is larger.

41. What are the contents of inspection before mechanical seal assemble?

(1) General inspection:

Mainly check the parts' models, specifications, performance, fit size and the damage of the gaps, pit, deformation and crack.

(2) Inspection of dynamic and static ring: seal surface should keep clean and bright and to check if there is the damage of collapse, pit, groove and scratch. It should further inspect if graphite annulus has crack. 

43. What are the requirements for the inspection of mechanical seal assisted sealing ring?

(1) The surface of the auxiliary sealing ring should keep smooth. No bubbles, cracks or gaps are allowed. The face dimensions should be uniform. The edges of O - shaped sealing ring should be 45 degrees angle to the working face;

(2) The hardness of the auxiliary sealing ring should be selected according to the pressure. High sealing pressure is equipped with high hardness; Lower sealing pressure is equipped with low hardness; Synthetic rubber material is used in auxiliary seal;

(3) The compression of auxiliary sealing ring should be suitable. Larger compression volume has good seal effect, but it is hard to assemble and has bad compensation ability at work.

(4) The compression of the auxiliary sealing ring should consider its other roles. The static O - shaped sealing ring has a dual function of sealing and anti-rotation. The amount of compression of sealing ring should be larger, so that the static ring will not turn and seal failure. Dynamic O - shaped sealing ring should reduce compression volume on the premise of ensuring the seal effect, avoiding that excessive compression and excessive resistance restraint floating compensation.

44.What is the inspection of mechanical seal spring?

The spring inspection includes the total winding number, the effective winding number, the free height, whether the axis is perpendicular to the end plane and the spring turns. But the spring must check the rotation, and the multiple springs don't need to check the rotation. The new spring should check its original free height. The free height should be measured. Compared with the original record, the residual deformation should be replaced. After cleaning the old spring, measure its elasticity and replace those spring that reduce 20% elastic force. The free height difference of multi-spring mechanical seal shall not be less than 0.5mm. 

45. What are the requirements for inspection of the shaft before mechanical seal installation?

(1) Check the coordinate dimensions, surface roughness, chamfering, axial direction of the shaft and the radial pulse.

(2) Check the wear of the shaft. The shaft may also be worn by O ring seals because of mechanical vibration and compensation for dynamic rings. It should be repaired and changed if there is worn.

(3) The sleeve seat and sleeve shall be in good condition.

46. What are the precautions for assembling the auxiliary sealing ring?

(1) Rubber-  auxiliary sealing ring can not be washed with gasoline or kerosene, so as to avoid large deformation and premature aging.

(2) O - shaped sealing ring is installed on the static ring assembly;

(3) When pushing the components, prevent the O - shaped sealing ring from damage, including drop, tear, bruise, coil edge and twist.

47.What are the considerations when installing static ring components?

(1) The static ring assembly shall be checked in from the rear of the static ring, and the static ring component shall be loaded into the gland or sealed chamber. In any case, it is not allowed to apply wallop to mechanical seals or components. The pressed surface should be covered with clean board or cloth to avoid damage to the sealing face.

(2) Whether the vertical degree of the sealing face of the shaft or axle sleeve is in line with the requirements.

(3) For the static mechanical seal, the static ring component of the anti-resale leads should be accurate; When advancing the static ring group, the pin groove of the component is aimed at the pin. After advancing in place, measure the distance from the end of the assembly to the end of the seal chamber and determine whether the installation is in place.

(4) When the bolt is pressed tightly to the end cover, it should be uniform and symmetrical, and it will be screwed out several times, not at once, so as to avoid deflection and even crushing graphite ring.

48. What are the requirements for inspection after mechanical seal assembly?

(1) Turning inspection. Due to the unfilled fluid, there are only a few lubricating oil on the sealing end of the ring seal, so it should not be used to avoid damaging the sealing end.

(2) Liquid inspection. Check if there is leakage, it can make car-test if not.

49. What are the inspection criteria for seal leakage?

(1) Padding sealing points are not more than 60 drops per minute.

50. What are the requirements for filling and adjusting padding?

(1).When filling padding, it is prohibited to use pneumatic or electric tools to turn the packing bolts. It should use the manual tool to turn the padding bolts. Padding should not be overstuffed, which can be added separately.

(2).Padding seal allows for leakage of media based on the principle of padding seal.  

When adjusting the compaction degree of the padding, the padding should not be compacted tight. When it needs to adjust the compaction degree, it can be adjusted separately.

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