A primary technical goal of a mechanical seal device of the present invention is to decrease assembly cost thereof as well as machining cost thereof and to prevent wear of seal surfaces by preventing occurrence of squealing noises of the seal surfaces. The mechanical seal device comprises a first seal ring which is one of a pair of seal rings and disposes an engagement portion at the outer circumferential surface, a retainer ring which has a first support portion supporting an inner diameter surface of the first seal ring and a second support portion engaging the engagement portion and is fixed with either a seal housing or a shaft, and a gasket which joins the retainer ring and the first seal ring in a sealing manner, wherein an engagement clearance (C) formed in a rotational direction between the engagement portion and the second support portion is within 0.5 mm.

Mechanical seal device

A mechanical seal (10) of the invention includes relatively rotatable seal rings (15)(16) and a secondary seal (65) therefore. The secondary seal (65)(140) is a C-shaped spring (71)(141) loaded gasket having upper and lower gasket legs (67)(68). The gasket (65)(140) is provided between two of the seal components, for example, between an axially movable seal ring (16) and a bellows flange (97). The gasket (140) has one leg thereof confined axially to transmit axial loads between the seal ring (16) and the bellows flange (97). Also, the upper and lower gasket legs are biased axially apart by a spring (71)(141) to permit radial movement between the seal ring and the bellows flange and also accommodate different rates of thermal expansion between the seal ring (16) and bellows flange (97).

Bellows seal with spring-loaded radial secondary seal

A process pump is provided including pressurized dry motor and integrated adapter cavities. The pump also includes a hermetically sealed motor housing and a specially arranged seal assembly. In accordance with one embodiment of the present invention, a hermetically sealed pump is provided including a motor, a motor housing, a gas supply port, a drive shaft, first and second rotational supports, an integrated adapter, a pump housing, a seal assembly, and an impeller. The motor is arranged to impart rotational movement to the drive shaft. The first and second rotational supports are arranged to support the drive shaft. The second rotational support is accommodated by the integrated adapter. The drive shaft is coupled to the impeller such that rotation of the drive shaft causes rotation of the impeller. The motor housing is disposed about the motor and defines a front end, a rear end, and a motor cavity. The pump housing is disposed about the impeller and defines a process fluid cavity. The integrated adapter is arranged to define an adapter cavity and to couple mechanically the rear end of the motor housing to the pump housing. The motor cavity and the adapter cavity are in fluid communication with one another and collectively define a hermetically sealed pressurized gas cavity having a motor cavity portion and an adapter cavity portion. The gas supply port is arranged to introduce pressurized gas into the pressurized gas cavity. The seal assembly is arranged to inhibit the passage of fluid from the process fluid cavity to the adapter cavity and to permit the passage of pressurized gas contained in the adapter cavity portion of the pressurized gas cavity to the process fluid cavity.

Hermetically sealed pump with non-wetted motor

A bellows type mechanical seal including a sealing ring and a mating ring, wherein either one of the sealing ring or the mating ring is retained in a housing and the other one is mounted on a shaft and wherein the sealing ring is supported by a bellows and the bellows has a retainer welded thereto on one of the sides for retaining the sealing ring and a collar welded on the other side to form a bellows assembly, is characterized in that the entire surface of the bellows assembly is covered by an erosion-resistant film formed by the physical vapor deposition, such as ion-plating.

Bellows type mechanical seal

A pump assembly (10) is provided including a motor (22), a motor housing (20), a dual-bearing rotational drive assembly (30), an integrated adapter (40), a pump housing (50), a seal assembly (54), and an impeller (52). In accordance with one embodiment of the present invention, the dual-bearing rotational drive assembly (30) comprises a drive shaft (32) and first and second bearings (36, 38). The motor housing (20) is disposed about the motor (22) and defines a front end and a rear end. The pump housing (50) is disposed about the impeller (52). The integrated adapter (40) is arranged to couple mechanically the rear end of the motor housing (20) to the pump housing (50). The motor (22) is arranged to impart rotational movement to the drive shaft (32) about a drive shaft axis. The drive shaft (32) is coupled to the impeller (52) such that rotation of the drive shaft (32) causes rotation of the impeller. The drive shaft (32) defines a first end disposed proximate the front end of the motor housing (30) and a second end disposed proximate the impeller (52) such that the drive shaft (32) extends from the front end of the motor housing (30), through the rear end of the motor housing (30), and to the pump housing (50). The first rotational support (36) is arranged proximate the front end of the motor housing (30). The second rotational support (38) is accommodated by the integrated adapter (40). The pump assembly (10) is arranged such that the drive shaft (32) and the first and second rotational supports (36, 38) define a rotational drive assembly characterized by the absence of additional rotational support between the first rotational support proximate the front end of the motor housing (30) and the second rotational support accommodated by the integrated adapter (40).

Pump assembly including integrated adapter

An improved gas seal having inboard and outboard seal units each defined by a pair of opposed and relatively rotatable seal faces, one face of each pair having appropriate grooves which communicate with a pressurized barrier gas, preferably an inert gas such as nitrogen. The inboard seal unit, at its other seal periphery, communicates with a process fluid being handled by a rotating equipment, namely a pump. Each seal unit has one of the seal rings, the nonrotating ring in the preferred embodiment, urged axially toward its opposed ring by a compact bellows which axially cooperates between the respective seal ring and a backing member. The bellows is positioned to create an isolation between the barrier and process fluids and to provide an effective diameter to provide desirable balance of pressures as imposed on the axially moving seal ring to optimize seal performance. The bellows at one end is connected to a support ring which is urged toward the adjacent seal ring with an annular gasket maintaining a soft sealed contact therebetween. The other end of the bellows is connected to a pressure piston which seats against a stationary gland. The process fluid urges the pressure piston into contact with the support ring to increase the sealing pressure at the gasket in the event of an improper balance between the pressures of the barrier and process fluids.

Double gas seal with bellows supported by backing and support rings

An improved gas seal having inboard and outboard seal units each defined by a pair of opposed and relatively rotatable seal faces, one face of each pair having appropriate grooves which communicate with a pressurized barrier gas, preferably an inert gas such as nitrogen. The inboard seal unit, at its other seal periphery, communicates with a process fluid being handled by a rotating equipment, namely a pump. Each seal unit has one of the seal rings, the nonrotating ring in the preferred embodiment, urged axially toward its opposed ring by a compact bellows which axially cooperates between the respective seal ring and a backing member. The bellows is positioned to create an isolation between the barrier and process fluids and to provide an effective diameter to provide desirable balance of pressures as imposed on the axially moving seal ring to optimize seal performance. The bellows is preferably a single convolution which is free of fixed securement to the moving seal ring.

William V. Adams

Papers

Double gas seal with bellows supported by backing and support rings

Double gas seal having an improved bellows arrangement

The Role Of Off-Design Pump Operation On Mechanical Seal Performance

Dual Gas Sealing Technology For Pump