Version of the seal for
rotating shafts

Sealing device consists of a fixed housing and installed in it with the ability to move in the radial and axial directions a stuffing box with a packing, and fitted with a console. The root of the console is connected to the housing through a rubber O-ring and the free end of the console is connected through another rubber O-ring with the stuffing box. A gland to tighten the packing is attached to the stuffing box.

In this version the stuffing box has a separator with a thrust balls and rests on an front flange through these balls. Balls are placed with the possibility of rolling on both the bearing surfaces of the front flange and the stuffing box.


How does the sealing
device operate?

The stuffing box with the packing and the gland are self-aligning coaxially with the shaft and when you turn on the equipment they begin to vibrate together with the shaft as a whole tracing the radial vibrations of the shaft due to the possibility of free inclination of the console in the radial directions.

Such a sealing device has an increased movability of stuffing box, which ensures reliable and long-term operation of equipment, even at large radial oscillation of the shaft and under high pressure of working medium.

To run the scheme of seal:
Stop the motion:
Basic information about the self-aligning
seal for the centrifugal pump type of SE 2500-60

As an example here it is demonstrated the sealing device for district heating network pump type of SE 2500-60 with a shaft diameter of 122mm and rotation rate of 1500rpm.

The design is based on the principle of radially movable stuffing box that become automatically self-centering coaxially with the shaft.

The device compensates the dynamic vibration of the shaft (up to 0.5mm on the radius) and the misalignment of the shaft (up to 1.5mm on the radius).


The sealing device is available as an assembly unit and additionally includes protective sleeves of the shaft and the packing rings set.

To install the sealing device on the pump you have 1) to screw the protective sleeves onto the shaft, 2) to put the sealing devices on both sides of the rotor, 3) to install of the pump cover, 4) to fasten the devices with bolts M16 to the pump and then 5) to load the stuffing box with packing rings.

The warranty period for the sealing device is 48 months.

The scheme of self-centering sealing device
and a description of the principle of its operation

The essence of the seal design is based on the known idea of radially movable stuffing box installed in a stationary seal housing. The main difficulty here is how to provide the maximal non-rigidity of the connection the moveable stuffing box with the immovable seal housing.

This coupling must be satisfied at least the following requirements:

● the stuffing box should be able to radially shift on "large" quantities;

● it should be able to execute multiple oscillatory movements in any radial direction;

● a resistance force preventing the displacement of the box should be as small as possible;

● an increase of the working medium pressure should not make the coupling to become more rigid.

As we developed the radial movability of stuffing box is achieved due to the fact that it is installed on the free end of the console, located in the sealing device housing. When the radial displacement of the shaft (rod, plunger) appears then the stuffing box with packing and a gland shift on the same value due to the free inclination of the console in the radial direction.

Thus even when misalignment of the shaft is up to 3mm on the radius, the stuffing box has the ability to self-align and to track radial vibrations of the shaft during operation of the equipment.

To reduce the friction forces arising at high dynamic displacement of the shaft, the stuffing box is equipped with a separator with the thrust balls, which serve as a bearing for the stuffing box and provide the ease of its motion.

For small dynamic displacements of the shaft, which is common in case of high speeds of rotation, as a bearing for the stuffing box can effectively serve a rubber O-ring that is thick enough (with a big size of its cross-section).

Due to the possibility to self-align the packing works with minimal contact pressure of the shaft, so it ensures reliable operation.

Shown below a schematic diagram represents only one of many possible embodiments of sealing device of console type. However some less essential details of the design (as well as a know-how) in the scheme have been omitted.

The design is protected of Eurasian (EAPO) patents # 1968 and # 013095 and patents of Ukraine # 47533 and # 86162 on the inventions.

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