Vacuum pumps

Claim 2

A vapour vacuum pump including a vertically arranged housing having an inlet at its upper end and seating an internal vapour jet assembly at its lower end, means defining upper and lower vapour nozzles within said hoousing; a flanged isolation valve secured to the inlet in a vacuum-tight manner, means for cooling the housing by heat transfer to a fluid coolant, said housing flaring outwardly and downwardly from below the inlet defining a region of maximum internal diameter from which it tapers inwardly and downwardly to a cylindrical portion circumscribing the lower part of said vapour jet assembly, said portion of maximum internal diameter positioned adjacent and extending above the level of said upper vapour nozzle, a plate assembly defining with said housing an annular gap for the flow of gas from the inlet to the interior of the housing, said plate assembly including a ring fixed to said housing and having a cap detachably mounted thereon to cover the opening in said ring, the internal diameter of said ring being greater than the external diameter of said vapor jet assembly, said cap including a depending skirt dimensioned to circumscribe and extend below said upper nozzle, said maximum diameter and flared portions of the housing defining with said plate assembly a baffle inhibiting the back-streaming of vapour molecules to the inlet, and said internal diameter of the cylindrical portion of said housing being approximately equal to the internal diameter of the inlet.

Claim 3

A vapour vacuum pump as claimed in claim 1, in which the plate assembly includes cooling means.

Claim 4

A vapour vacuum pump as claimed in claim 2, in which the coolant for the plate assembly is the same as that which is used to cool the housing.

Claim 5

A vapour vacuum pump as defined by claim 1 in which said cap includes a depending member in contact with a projection on the top of said vapour jet assembly to preclude lateral movement thereof.

Claim 6

A vapour vacuum pump as defined by claim 1 in which a resilient strap is secured to said ring and extends diametrically across the top of said cap to bias said cap into engagement with said ring.

Claim 7

A vapour vacuum pump including a vertically arranged housing having an inlet at its upper end, an isolation valve secured to said inlet, said valve including an annular flange attached to said housing encircling said inlet, a rotary shaft extending through at least a portion of said flange and across said inlet, a valve plate detachably mounted on said shaft and seated within said flange, said shaft dimensioned for axial withdrawal from said flange to provide unobstructed access to the interior of said housing through said inlet, a vapour jet assembly including upper and lower vapour nozzles positioned within said housing and seated at the lower end of said housing, means for cooling said housing by heat transfer to a fluid coolant, said housing including portions flared outwardly and downwardly from the inlet to a region of maximum internal diameter, said housing further configured to taper inwardly and downwardly connecting with a cylindrical housing portion circumscribing the lower portion of said jet assembly disposed therewithin, said portion of maximum internal diameter being disposed at least partially at the level of and encircling the uppermost vapour nozzle, a plate assembly which together with said housing defines an annular gap for the flow of gas from the inlet to the interior of said housing, said portion of said housing of maximum internal diameter and said flared portions of said housing together with the plate assembly defining a baffle inhibiting the backstreaming of vapour molecules from the interior of said housing to the inlet when said pump is in operation, the diameter of the opening in said flange of said isolation valve being approximately equal to the internal diameter of the cylindrical portion of the housing and of greater diameter than the maximum external diameter of said vapour jet assembly.

Claim 8

A vapour vacuum pump including a vertically arranged housing having an inlet at its upper end, an isolation valve secured to said inlet, said valve including an annular flange attached to said housing encircling said inlet, a rotary shaft extending through at least a portion of said flange and across said inlet, a valve plate detachably mounted on said shaft and seated within said flange, said shaft dimensioned for axial withdrawal from said flange to provide unobstructed access to the interior of said housing through said inlet, a vapour jet assembly including upper and lower vapour nozzles positioned within said housing and seated at the lower end of said housing, means for cooling said housing by heat transfer to a fluid coolant, said housing including portions flared outwardly and downwardly from the inlet to a region of maximum internal diameter, said housing further configured to taper inwardly and downwardly connecting with a cylindrical housing portion circumscribing the lower portion of said jet assembly disposed therewithin, said portion of maximum internal diameter being disposed at least partially at the level of and encircling the uppermost vapour nozzle, a plate assembly which together with said housing defines an annular gap for the flow of gas from the inlet to the interior of said housing, said portion of said housing of maximum internal diameter and said flared portions of said housing together with the plate assembly defining a baffle inhibiting the backstreaming of vapour molecules from the interior of said housing to the inlet when said pump is in operation, the diameter of the opening in said flange of said isolation valve being approximately equal to the internal diameter of the cylindrical portion of the housing and of greater diameter than the maximum external diameter of said vapour jet assembly.

Claim 9

A vapour vacuum pump as claimed in claim 6 in which said flange includes conduit means selectively connectable to the interior of said pump and in communication with the space above the valve plate when the latter is in its closed position.

Claim 10

A vapour vacuum pump as defined by claim 7 in which an auxiliary vacuum pump assembly is selectively connectable with the said conduit.