Shaft sealing devices

Dual seals and anxiliary shaft sealing devices (see data sheets). ... 

Rig. 1.14 Classification of shaft sealing devices with regard to system pressure and the shaft speed... 

SHAFT SEAL - Device used to prevent leakage between shaft and housing. 

Labyrinth Seals The labyrinth is one of the simplest of the many sealing devices. It consists of a series of circumferential strips of met extending from the shaft or from the bore of the shaft housing to form a cascade of annular orifices. Labyrinth seal leakage is greater than that of clearance bushings, contact seals, or filmriding se s. 

The shaft seal (see subsection Shaft Seals ) generally is a close-clearance labyrinth-type seal. It is desirable that there be available a suitable pressurized buffer gas for injection into the intermediate point in the seal, such gas to be available at an absolute pressure well above the highest shaft pressure to be sealed. Then the seal-gas system may consist of only a filter, a flow-indicating device, and a throttle... 

Centrifugal (radial inflow) turboexpanders are well adapted to such energy conservation schemes and, with recent developments that have increased their reliability, are suitable for unattended service on a 24-hour, 7-day week operational basis. Some of the recent developments include better shaft seals, thrust bearing monitoring, and superior control devices. 

A typical mechanical contact shaft seal has two major elements, as seen in Figure 13-30. These are the oil-to-pressure-gas seal and the oil-to-unconta-minated-seal-oil-drain seal or breakdown bushing. This type of seal will normally have buffering via a single ported labyrinth located inboard of the seal and a positive shutdown device, which will attempt to maintain gas... 

In dealing with the problem of mechanical stress one has to distinguish between the aspects which concern device construction and those which are of concern to the device users. Information over the mechanical forces, which operate on the stirrer, the shaft, the shaft bearings and the shaft seal, together with the critical stirrer speed etc., can be obtained from the brochures of the stirrer manufacturers [0.14, 526] and from research papers such as [123, 393, 420]. In this section only those aspects which are of interest to the comparatively large group of users of mixing equipment will be considered. 

The temperature of the water in the seal assembly is maintained within acceptable limits by a water-cooled heat exchanger. Water is also injected into the seal area from an external seal injection system. The performance of the shaft seal system is monitored by pressure and temperature sensing devices in the seal system. The seal assembly can be replaced without draining the pump casing or removing the shaft. 

Lip seal device utilizing the planned interference between a rubber lip and a mating surface (such as a shaft) to prevent leakage. 

Fig. 10. The Groth ZG 5 centrifuge. R, rotor R, stationary shaft T, Teflon seal K, K, chambers for gas scoops S, S2, scoops V, gas supply M, manometer Z, Z2, tapping points for enriched and depleted gas P, P2, vacuum chambers E, electromagnet for eddy current heating Tb, Tb2, temperature measuring devices K, cooling coil and D, D2, labyrinth seals.

An effective auxiliaiy device frequently used with packing and rotary shafts is the seal cage (or lantern ring), shown in Fig. 10-110. The seal cage provides an annulus around the shaft for the introduction of a lubricant, oil, grease, etc. The seal cage is also used to introduce liquid for cooling, to prevent the entrance of atmospheric air, or to prevent the infiltration of abrasives from the process liqmd. 

O Ring A device used to seal a shaft of a device or a pipeline that is conveying a fluid. 

A device that effectively seals a pump against leakage around the shaft by means of various rubber/fiber packing materials. 

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