Cryogenic apparatus

Claim 2

Cryogenic apparatus including a control unit, a probe and switching means, the control unit being connected to a gas source whereby gas can be passed through the unit to the probe, a restricted orifice in the probe to direct gas to the probe tip to thereby effect cooling of the tip, the apparatus having control means so that the gas flow to the probe is prevented unless the gas pressure and flow rate are within predetermined limits.

Claim 3

Apparatus as claimed in claim 1 wherein the switching means operates a solenoid gas valve, the driving unit for which is interconnected with a level detector sensitive to the output of gas pressure and flow detector whereby on the gas pressure being greater or less than a predetermined maximum the driving unit is prevented from operating.

Claim 4

Apparatus as claimed in claim 2 wherein operation of the level detector also initiates the operation of a warning device.

Claim 5

Apparatus as claimed in claim 2 wherein a delay circuit is provided to prevent the operation of the level detector during a period corresponding to the time in which the unit is flushed.

Claim 6

Apparatus as claimed in claim 1 wherein there is provided a gas pressure and flow detector having associated with its output a level detector arranged to provide a warning on the gas pressure being slightly below a predetermined minimum.

Claim 7

Apparatus as claimed in claim 1 wherein the switching means operates a solenoid gas valve including a flushing system which must be operated before the switching means is effective including a manual flushing circuit, an automatic flushing circuit which operates when the unit is in itself actuated, a latching system controlling all other functions initiated by operation of one of the flushing circuits, operation of the flushing circuit also causes operation of the solenoid valve for a predetermined period, the arrangement being such that if the valve does not operate the latching system drops out.

Claim 8

Apparatus as claimed in claim 6 wherein the latching system is barred from operating if the probe is attached to the control unit.

Claim 9

Apparatus as claimed in claim 6 having a warning device which operates until flushing is completed.

Claim 10

Apparatus as claimed in claim 7 wherein after completion of the flushing operation means are provided so the solenoid valve driving unit cannot operate until a probe is attached.

Claim 11

Apparatus as claimed in claim 1 wherein the probe includes a thermocouple interconnected to a first level detector in the control unit which level detector controls a visible indication that the temperature of the probe has dropped below a preselected minimum temperature.

Claim 12

Apparatus as claimed in claim 1 wherein the probe includes a thermocouple interconnected to a second level detector in the control unit which level detector controls a visible indication that the temperature of the probe has risen above a preselected maximum temperature.

Claim 13

Apparatus as claimed in claim 1 wherein the probe includes a thermocouple connected to a third level detector in the control unit, and a heating unit in the probe to prevent the probe body from freezing and to heat the probe tip when necessary, the heater being controlled by operation of the level detector at a preselected thermocouple temperature.