How is the pumping ring applied in the mechanical seal circulation system (II)

Pumping rings of mechanical seal devices are commonly used to drive seal fluid circulation in API schemes 23, 52, and 53. This article follows the previous article and introduces schemes 52 and 53.

1.API scheme 52
API plan 52 is that the external liquid storage tank provides buffer fluid for the outer seal of arrangement II (each set of manifold seals has two pairs of sealing surfaces, and the pressure between the two pairs of sealing surfaces of the mechanical seal is lower than the medium to be sealed),to discharge the medium steam leaked from the front seal in time, and ensure that the buffer fluid pressure is lower than the medium pressure.The storage tank used in this scheme is usually a pressure tank, and there is a coil cooling buffer in the tank. Under normal circumstances, this scheme can ensure that the process medium is not leaked into the atmosphere. By detecting the liquid level or pressure change of the buffer liquid in the liquid storage tank, it can be known whether there is a large amount of leakage in the front seal, so as to know the working condition of the main seal. API scheme 52 is often used in olefin chemical media pumps. The main performance of the cartridge seal depends on the front seal, and it can be used together with API scheme 11, 21, etc.

2. API scheme 53
API plan 53 is to use a spacer liquid storage tank with a pressure higher than the medium to provide liquid circulation for the front seal and outer seal of arrangement III, and the spacer liquid circulation is driven by the pumping ring of the mechanical seal auxiliary system. API scheme 53 is subdivided into three structures: 53A, 53B, and 53C.(1) The spacer fluid of 53A is directly pressurized by nitrogen gas, and it is used in the working condition with a pressure lower than 2MPa, and the liquid storage tank is a pressure tank; （2）Cooled by a heat exchanger, used for working conditions with a pressure higher than 2MPa, the liquid storage tank is a heat exchanger; (3) The 53C spacer fluid is indirectly pressurized by the medium through the booster tank, and is used for medium pressure In the case of large fluctuations, the liquid storage tank is a pressurized tank.

In practical applications, the working condition of the front seal is analyzed by detecting the liquid level or pressure change of the spacer liquid in the liquid storage tank and observing the leakage of the outer seal. With the sealing system of API scheme 53, the leakage direction of the pre-stage seal in normal operation is the medium, that is, the spacer fluid leaks to the medium, so it can ensure zero escape of the medium, which is conducive to environmental protection requirements. It is often used in sealing for toxic, flammable, explosive, strong corrosion, etc media.