Cryogenic device operable in single or dual phase with a range of nozzle sizes and method of using the same

In combination:

• a Dewar chargeable with liquid cryogen;
• means for delivering cryogen into an expansion chamber equipped with a readily detachable nozzle located exteriorly of said Dewar;
• a pressure regulated source of pressurized gas connected to said expansion chamber;
• manually controlled means for venting gas from said expansion chamber while simultaneously reducing substantially the flow of gas thereto from said pressurized gas source and effective in one of two normal operating positions thereof to provide single phase gas flow from said nozzle and to provide two phase gas and liquid particle cryogen flow from said nozzle in the other position thereof, irrespective of any size of nozzle between 0.010 and 0.045 inches in diameter.

That method of selectively dispensing a jet of cryogen in gaseous phase only and in a jet of gas and finely divided liquid particles at the user's option from any selected one of dispensing nozzles ranging in size from 0.010 to 0.045 inches in diameter which method comprises:

• storing liquid cryogen in a Dewar under a predetermined pressure;
• releasing liquid cryogen from said Dewar through an orifice into an expansion chamber in heat exchange with the atmosphere and equipped with means for mounting a selected one of said dispensing nozzles thereon;
• providing said expansion chamber with means for venting gas therefrom to the atmosphere independently of said nozzle in an amount to lower the expansion chamber pressure less than about one psig and effective to convert a jet of single phase gaseous cryogen to a jet of dual phase gas and liquid cryogen particles when a nozzle of about 0.021 inches in diameter or smaller is in use;
• providing said expansion chamber with a flow-controllable connection to a source of pressure regulated gas;
• and
• opening said gas venting means while reducing the flow of gas from said pressure regulated source when a nozzle larger than about 0.021 inches in diameter is in use and thereby effective to convert the jet of cryogen dispensed from said nozzle from single phase cryogen to two phase gas and liquid cryogen particles.

A cryogenic device for selectively dispensing either a single phase or a dual phase jet of cryogen from nozzles of different diameters at the user's option comprising:

• means for storing liquid cryogen at a predetermined miximum pressure;
• an expansion chamber in communication with said pressurized cryogen via an expansion port;
• means for detachably connecting any one of a plurality of nozzles to an outlet port of said expansion chamber and which nozzles have a port diameter ranging between 0.010 and 0.045 inches;
• venting passage means for said expansion chamber equipped with a normally closed venting valve operable, when open, to reduce the pressure in said expansion chamber by a major fraction of one pound;
• adjustable means for regulating the flow of pressurized gas to said expansion chamber from a pressure regulated source thereof;
• and
• manually operable means to open said venting valve and to interrupt the flow of gas from said pressure regulated source to said expansion chamber and thereby substantially instantly convert the jet dispensed from the one of said nozzles then in use from single phase gas to two phase gas and liquid cryogen particles.

In a cryogenic device:

• a container for normally pressurized liquid cryogen;
• an expansion chamber connected to said container to receive liquid cryogen therefrom;
• a nozzle having an internal diameter between 0.010 inches and 0.045 inches;
• first means to reduce the pressure in said expansion chamber to effect an increase in the flow of pressurized liquid cryogen into said chamber from said container and to change the flow of fluid from said chamber through said nozzle from single phase to dual phase with said nozzle having a diameter in the range of 0.010 inches to 0.021 inches;
• and
• second means to provide gas under pressure to said chamber to raise the pressure therein to approximate the pressure present when a smaller nozzle with a nozzle connected having a diameter in the range of 0.033 inches to 0.045 inches is connected in order to effect a flow of single phase gas through said nozzle, said flow changing from single phase to dual phase upon the substantial closing of said second means and the opening of said first means.

In a cryogenic device:

• a container for liquid cryogen
• an expansion chamber connected to said container to receive liquid cryogen therefrom in which the entering cryogen vaporizes partially or totally to gas depending upon the pressure present;
• a nozzle having an internal diameter in the range of 0.010 inches to 0.045 inches;
• a source of gas under pressure connected to said expansion chamber to produce a suitable pressure in the chamber to limit the flow of cryogen into said expansion chamber from said container to produce a flow of single phase cryogen through a nozzle having an internal diameter greater than 0.021 inches;
• first means operable to reduce the pressure in said expansion chamber to increase the flow of liquid cryogen from said container into said expansion chamber resulting in a change in the cryogen jetting from said container through said nozzle from single phase to dual phase flow with the nozzle connected to said chamber having a diameter in the range of 0.010 inches to 0.045 inches;
• and
• second means operable to stop the flow of pressurized gas into said expansion chamber from said source to cause the flow of cryogen through the nozzle to change from single phase flow to dual phase flow when the nozzle has a diameter greater than 0.021 inches.