Classification of mechanical seals leaking

The location of mechanical seal leakage is quite extensive, involving almost all fluid transport and storage objects. The forms and types of leaks are also varied. First, the classification of leak forms is introduced:

1. Classification according to the mechanism of leakage

(1) Interface leakage: a leakage between the surface of the seal (gasket, packing) and the surface of the contacting part. Such as leakage between flange and gasket, packing and shaft or stuffing box.

(2) Infiltration leakage: The medium penetrates through the capillary tube of the seal (gasket, packing) body, and this leakage occurs on the seals made of materials such as plant fibers, animal fibers and chemical fibers with poor compactness.

(3) Destructive leakage: a dangerous leakage caused by the increase of the leakage gap of the seal due to rapid wear, deformation, deterioration, failure and other factors.

2. Classification by leakage

Liquid medium leakage is divided into five levels

(1) No leakage: No leakage detected shall prevail.

(2) Leakage: A slight leak. There are obvious signs of medium leakage on the surface, like oozing sweat. The traces were wiped off and the leak traces reappeared a few minutes later.

(3) Drip: The medium leaks into a water ball, slowly flows down or drips, wipes off the traces, and reproduces the water ball leakage within 5 minutes is a drip.

(4) Heavy leakage: The medium leakage is relatively heavy, and it continuously flows down or drips in the form of water beads, but it does not reach the level of flow.

(5) Flow: The medium leaks seriously, and the medium spews continuously and flows in a line.

Gaseous medium leakage is divided into four levels

(1) No leakage: use a small piece of paper or fiber to check the static state, and use soapy water to check that there is no bubble.

(2) Leakage: Use a small piece of paper to check for slight fluttering, use soapy water to check for air bubbles, use wet litmus paper to check for signs of discoloration, and light-colored smoke can be seen in colored gaseous media.

(3) Leakage: fly when checking with a small piece of paper, check bubbles in a string with soapy water, change color immediately with wet litmus paper, and the colored gas is clearly visible.

(4) Heavy leakage: The leaking gas produces noise, which is audible.

3. Classification according to the time of leakage

(1) Frequent leakage: a leakage that occurs from the beginning of installation, operation or use. Mainly due to construction quality or poor installation and maintenance quality and other reasons.

(2) Intermittent leakage: leakage occurs after operation or use for a period of time, and it stops when it leaks. This kind of leakage is caused by factors such as unstable operation, changes in the medium itself, the level of groundwater levels, and changes in outside air temperature.

(3) Sudden leakage: sudden leakage. This leakage is caused by misoperation, overpressure and overtemperature, and is also related to factors such as fatigue damage, corrosion and erosion. This is a very dangerous leak.

4. Classify according to the leaked sealing part

(1) Static seal leakage: a leakage between seal pairs without relative motion. Such as leakage of joint surfaces such as flanges, threads, boxes, and rolls. Relatively speaking, this kind of leakage is easier to manage.

(2) Dynamic seal leakage: there is a kind of leakage between the relative moving seal pairs. Such as the leakage of dynamic seals between the rotating shaft and the shaft seat, between the reciprocating rod and the packing, between the moving ring and the static ring. Such leaks are more difficult to manage.

(3) Leakage of closing parts: a leakage between closing parts (gate, disc, ball, cock, throttle cone, slider, plunger, etc.) and closing seat (valve seat, cock body, etc.). This type of seal is different from static seal and dynamic seal. It has the functions of cut-off, reversing, throttling, adjustment, decompression, safety, non-return, separation, etc. It is a special sealing device. Such leaks are difficult to manage.

(4) Body leakage: a kind of leakage caused by materials such as shell, pipe wall, valve body, ship hull, and dam body. Leakage of defects such as blisters, cracks, etc.

5. Classification according to the hazard of leakage

(1) Leakage is not allowed: Refers to special working conditions where no leakage at the sealing part can be detected by feeling and general methods. Such as extremely flammable, explosive, highly toxic, radioactive media and very important parts, leakage is not allowed. Nuclear power plant valves are required to be used for decades and remain intact.

(2) Permissible micro-leakage: refers to the working condition where the medium allows micro-leakage without causing harm.

(3) Allowable leakage: refers to the leakage of water and air media under certain circumstances.

6. Classification according to the flow direction of the leaking medium

(1) External leakage: a phenomenon in which the medium transfers mass from the inside to the outside space.

(2) Inward leakage: a phenomenon in which the material in the external space transfers mass to the inside of the pressurized body. Such as air and liquid penetration into vacuum equipment containers.

(3) Internal leakage: a phenomenon in which the medium in the sealing system produces mass transfer. Such as leakage after the valve is closed in the sealing system. Internal leaks are difficult to detect and manage.

7. Classification according to the type of leakage medium

Such as air leakage, steam leakage, water leakage, oil leakage, acid leakage, alkali leakage, salt leakage and so on.