Static seal

A pump assembly including a static pump casing, an impeller and a shaft mounting the impeller and being mounted for rotation within the pump casing, and a composite seal arrangement for sealing between rotary components connected to the shaft and static components connected to the casing, both under stationary and running conditions, characterised in that the composite seal arrangement includes static seal components including a static seal, comprising:

• a rotary seal body having an annular base portion which is drivingly mountable on a rotary component such as a drive shaft mounting an impeller of a pump, and an annular, axially extending, cantilever portion connected at one end to the base portion, an opposed end of the cantilever portion being unconnected;
• a rotary seal face fast with the cantilever portion;
• and
• circumferential weights or masses connected to the cantilever portion, characterised in that the cantilever portion comprises a radially inner sleeve portion and a plurality of axially extending, circumferentially arranged, fingers fast with the radially inner sleeve portion and divided by grooves or interruptions to define individual body formations along a radially outer face of the cantilever portion,
• wherein the masses are in the form of elongate mass bodies, embedded in the cantilever portion toward the unconnected end of the cantilever portion, each mass body being located on a pin, the mass bodies and pins being integrally moulded at least partially within the cantilever portion.

A method of operating a static sealing arrangement characterised in that the static sealing arrangement includes a static seal comprising

• a rotary seal body having an annular base portion which is drivingly mountable on a rotary component such as a drive shaft mounting an impeller of a pump, and an annular, axially extending, cantilever portion connected at one end to the base portion, an opposed end of the cantilever portion being unconnected;
• a rotary seal face fast with the cantilever portion;
• and
• circumferential weights or masses connected to the cantilever portion, characterised in that the cantilever portion comprises a radially inner sleeve portion and a plurality of axially extending, circumferentially arranged, fingers fast with the radially inner sleeve portion and divided by grooves or interruptions to define individual body formations along a radially outer face of the cantilever portion, the masses being in the form of elongate mass bodies, embedded in the cantilever portion toward the unconnected end of the cantilever portion, each mass body being located on a pin, the mass bodies and pins being integrally moulded at least partially within the cantilever portion co-axially fast with a rotor of a pump, and a stationary, circumferential sealing face, co-axially arranged relative to said rotor, and fast with a casing of the pump, the static seal face being complemental to the rotary seal face of the static seal, the method including:
• during rotation of the rotor, causing at least part of the cantilever portion of the seal body to dilate radially under the influence of centrifugal force generated by the masses which rotate, to establish a running clearance between the rotary seal face and the static seal face;
• and
• when the rotor is stationary, urging the rotary seal face into sealing contact with the static seal face.

A method of retrofitting a static seal into a pump assembly, characterised in that the method comprises the steps of:

• removing an existing seal from the pump assembly;
• and
• replacing the existing seal with a static seal which comprises a rotary seal body having an annular base portion which is drivingly mountable on a rotary component such as a drive shaft mounting an impeller of a pump, and an annular, axially extending, cantilever portion connected at one end to the base portion, an opposed end of the cantilever portion being unconnected;
• a rotary seal face fast with the cantilever portion;
• and
• circumferential weights or masses connected to the cantilever portion, characterised in that the cantilever portion comprises a radially inner sleeve portion and a plurality of axially extending, circumferentially arranged, fingers fast with the radially inner sleeve portion and divided by grooves or interruptions to define individual body formations along a radially outer face of the cantilever portion, the masses being in the form of elongate mass bodies, embedded in the cantilever portion toward the unconnected end of the cantilever portion, each mass body being located on a pin, the mass bodies and pins being integrally moulded at least partially within the cantilever portion.

A pump assembly including a static pump casing, an impeller and a shaft mounting the impeller and being mounted for rotation within the pump casing, and a composite seal arrangement for sealing between rotary components connected to the shaft and static components connected to the casing, both under stationary and running conditions, characterised in that the composite seal arrangement includes static seal components including a static seal comprising:

• a rotary seal body having an annular base portion which is drivingly mountable on a rotary component such as a drive shaft mounting an impeller of a pump, and an annular, axially extending, cantilever portion connected at one end to the base portion;
• a rotary seal face fast with the cantilever portion;
• and
• circumferential weights or masses connected to the cantilever portion, characterised in that the masses are in the form of elongate mass bodies, embedded in the cantilever portion toward the unconnected end of the cantilever portion, each mass body being located on a pin, the mass bodies and pins being integrally moulded at least partially within the cantilever portion which is in the form of a moulding.

A method of operating a static sealing arrangement characterised in that the static sealing arrangement includes a static seal comprising:

• a rotary seal body having an annular base portion which is drivingly mountable on a rotary component such as a drive shaft mounting an impeller of a pump, and an annular, axially extending, cantilever portion connected at one end to the base portion;
• a rotary seal face fast with the cantilever portion;
• and
• circumferential weights or masses connected to the cantilever portion, characterised in that the masses are in the form of elongate mass bodies, embedded in the cantilever portion toward the unconnected end of the cantilever portion, each mass body being located on a pin, the mass bodies and pins being integrally moulded at least partially within the cantilever portion which is in the form of a moulding, co-axially fast with a rotor of a pump, and a stationary, circumferential sealing face, co-axially arranged relative to said rotor, and fast with a casing of the pump, the static seal face being complemental to the rotary seal face of the static seal, the method including:
• during rotation of the rotor, causing at least part of the cantilever portion of the seal body to dilate radially under the influence of centrifugal force generated by the masses which rotate, to establish a running clearance between the rotary seal face and the static seal face;
• and
• when the rotor is stationary, urging the rotary seal face into sealing contact with the static seal face.

A method of retrofitting a static seal into a pump assembly, characterised in that the method comprises the steps of:

• removing an existing seal from the pump assembly;
• and
• replacing the existing seal with a static seal comprising:
• a rotary seal body having an annular base portion which is drivingly mountable on a rotary component such as a drive shaft mounting an impeller of a pump, and an annular, axially extending, cantilever portion connected at one end to the base portion;
• a rotary seal face fast with the cantilever portion;
• and
• circumferential weights or masses connected to the cantilever portion, characterised in that the masses are in the form of elongate mass bodies, embedded in the cantilever portion toward the unconnected end of the cantilever portion, each mass body being located on a pin, the mass bodies and pins being integrally moulded at least partially within the cantilever portion which is in the form of a moulding.