초록 ▼

In an apparatus for producing liquid nitrogen by supplying to a nitrogen gas separated from the atmosphere and then purified by an air separating device (4) into an insulated container (1) equipped with an extremely low temperature refrigerator, there are provided a pressure sensor (21) for detectin

In an apparatus for producing liquid nitrogen by supplying to a nitrogen gas separated from the atmosphere and then purified by an air separating device (4) into an insulated container (1) equipped with an extremely low temperature refrigerator, there are provided a pressure sensor (21) for detecting a pressure within a product vessel (20) of the air separating device (4) and a negative pressure sensor (16) for detecting a negative pressure within the insulated vessel (1) respectively. When at least one of both sensors (21) (16) detects a freezing of an impurity gas contained in the supplied nitrogen gas by reaching a predetermined pressure, an operation of the extremely low temperature refrigerator is stopped depending on the detection by one of both the sensors.

대표청구항 ▼

An apparatus for producing liquid nitrogen comprising: a refrigerant storage vessel composed of an insulated container, said refrigerant storage vessel including an opening formed at an upper end thereof; an extremely low temperature refrigerator having a cold head associated therewith, said cold he

An apparatus for producing liquid nitrogen comprising: a refrigerant storage vessel composed of an insulated container, said refrigerant storage vessel including an opening formed at an upper end thereof; an extremely low temperature refrigerator having a cold head associated therewith, said cold head projecting into the opening formed in said refrigerant storage vessel; means for producing a supply of nitrogen gas including a device for separating nitrogen gas from air, the nitrogen gas being supplied to said refrigerant storage vessel in a gaseous phase such that the nitrogen gas is liquified by a cold heat supplied from said cold head, said device including a product vessel; a pressure sensing instrument disposed in said product vessel; a negative pressure sensor connected to within said refrigerant storage vessel; and control and indication means, responsive to said pressure sensing instrument and said negative pressure sensor, for interrupting operation of said cold head and providing an alarm upon detection by said pressure sensing instrument that a pressure within said product vessel has lowered to a predetermined pressure or upon detection by said negative pressure sensor that a pressure within said refrigerant storage vessel has lowered below a predetermined negative pressure.