• 600 Automatic On 50 Liter Dewar2
  • 855 Automatic Gas Pump 1
  • 100 Liter Dewar

855 N2 Cold Gas Supply System

Specifications and Options

NORHOF N2 Cold Gas Supply System #855 Series

Norhof manufactures N2 cold gas supply systems. Nitrogen  (LN2) is used as the cooling medium and is taken from a storage vessel (Dewar) with low pressure (max. 300 mBar) and delivered (pumped) through a line to the application in a gaseous cold flow

Working principle

The pressure above the liquid level inside the Dewar is built by heating a small amount of liquid in the bottom of the Dewar. With only up to 300 mBar of overpressure, the cold gas will gentle flow out of the outlet pipe.  In these systems a pressure less storage Dewar is used as a reservoir for LN2. On the Dewar our unique cold gas pump is mounted. Inside the housing of the pump a microprocessor is used to control the various actions, depending upon the mode selected. The selection of a particular mode is made by a 16-position switch, also located inside the pump housing. By controlling the pressure at time of cold gas transport, the flow is controlled and thus any temperature between ambient and -160°C can be realized.

cold N2 gas supply may have its application advantages, however, important to know it has much lower heat removal capacity compared with liquid Nitrogen

Any #855 series model will work without modifications as:

– autonomous stand-alone unit;
– direct remote controlled unit;
(controlled by your existing PID controller, PLC, computer with A/D conversion card, etc.);
– will operate on 24 V, DC or with our power supply (115V or 230 V);
– a system with almost no installation time required.
– no need for a pressurized supply of LN2;
– no need for a cryogenic solenoid valve ;
– no need for additional control instruments.

When LN2 is required, a small overpressure is generated by a small heater element in the LN2, and liquid flows out of the system like water from a tap, without spilling, noise, vibrations etc.




To display sensor temperature, vessel pressure, status of LED’s on the pump etc. our Norhof Monitoring software is included with #855 series pump. This software works under Windows ’98 – 2000 – ME – NT – Vista – W7 – Windows 10


855 series Technical Specifications

Static evaporation rate < 0,5 liters per day
Flow rate adjustable from 0.01mBar to 270 mBar (by potmeter on pump)

== up to 60 liter / minute

(with a fill line of 2 meter and 6.6 mm ID)

Maximum working pressure < 300 mBar
Reaction time +/- 1 minutes for cooling down the fill line (with 2 meters fill line)
Power connection 115V / 230V AC with supplied power supply or 24 Volt DC
Power consumption average 125 Watts, during pumping 250 watts
Storage container volume 50 Liter 100 Liter
Outside dimensions (diameter) 500  mm 500 mm
Height dimensions  875  mm 1235 mm
Weight (empty, full) 17 / 57,5  kg 32 / 113 kg
Standard fill line 9.6 mm OD, 6.6 mm ID PTFE tube, with 32mm foam insulation
System includes Dewar, pump, fill line 2.00 m, power supply, cables, 2 level sensors,

PC software.

Working modes #855, working mode 1 to 7 for control
External control #855, 5 volt signals for ON, OFF and RS232 signals for ON, OFF
PC software Monitor software, to monitor pump behavior, and for some working modes to adjust some parameters.
Alarms/warning                 acoustical/ visual / mechanical Dewar empty, Dewar 5 liters LN2 left, broken sensor(s), frozen

alarm, mechanical overpressure protection valve.

Options Transport trolley 5 wheels (10 cm height)

Stand for pump (when Dewar is refilled)

Custom built adaptor to fixate sensor(s) on application


Summary of #855 series

Model:   #855
autonomous operation      √
remote control by TTL signal      √
remote control by +24V signal      √
display system status on PC screen      √

Norhof pump stand

Norhof Trolley

50 liter Dewar with trolley

50 liter Dewar with trolley strapped

50 liter Dewar

100 liter Dewar

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