Liquid Nitrogen – An Intelligent system

News 1 April 2019



F-DGSi manufactures Liquid Nitrogen Plants (LNPs) and are designed to reliably produce liquid nitrogen (LN2) directly from air. F-DGSi Engineering –  We use PSA Nitrogen technology. These units produce high purity gaseous Nitrogen from Air. F-DGSi LN2 units are integrated with a Cryorefrigerator to convert gas to liquid Nitrogen inside your laboratory. With F-DGSi fully integrated Liquid Nitrogen plant, the customer only needs to connect power.


How does it work?

F-DGSi manufactured Liquid Nitrogen Plants are designed to produce Liquid Nitrogen (LN2) directly from air inside your premises. The Liquid Nitrogen plant comprises of below components:

  • Air Compressor – It is required for providing air into the Nitrogen Generator. It is present inside the Liquid Nitrogen generator itself.
  • Air Filters – Multiple filters (oil, dust etc.) are used to purify the compressed air before it enters the PSA Nitrogen generator.
  • PSA technology Nitrogen Generator – The Nitrogen Generator works on the principle of Nitrogen separation from air. For this F-DGSi recommends and uses only PSA (pressure swing adsorption) technology for no compromise in purity.
  • Dewar Assembly – Once the liquid Nitrogen is produced, it is taken to a Dewar assembly. The Dewar assembly is designed for storage and extraction of LN2. The Dewar is a stainless steel, vacuum jacketed container built for the purpose of storing liquid nitrogen with minimal boil off (losses). With different models comes different storage capacities of Dewar.
  • Level Indicator/Switch – The operation of the LNP is automatically controlled by the level indicator mounted on Dewar. The level indicator is preset to turn off the cryo-refrigerator when the Dewar is full, and places the Liquid Nitrogen plant in standby mode.
  • Cryorefrigerator – The Cryorefrigerator consists of a cold head, Helium compressor package and a pair of stainless steel flexible helium lines. The cold head is mounted into the top of the Dewar. The cold head extends down into the neck of the Dewar for the purpose of cooling the nitrogen entering the Dewar to -196 ̊ C. The Nitrogen gas liquefies on contact or continuous touch with the cold head or heat exchanger. The liquefied Nitrogen drips off the heat exchanger down into the Liquid Nitrogen plant inside the Dewar.


Liquid Nitrogen Generator consists of?

  1. Air Compressor
  2. PSA Nitrogen Generator
  3. Helium Compressor
  4. Dewar
  5. Hose Pipe
  6. Water Chiller (Optional)
Max L/Day 10 20 30 40 60
Dewar Capacity (L) 35 100 160 210


Liquid Nitrogen Benefits for the customer

Autonomy, reliability and availability of liquid Nitrogen

Easy to operate

Customer needs to provide only power connection

Round-the-clock liquid Nitrogen availability

No more waiting for liquid container delivery from vendor

Minimal Maintenance


Liquid Nitrogen Applications

Flow Diagram

Double Casing SS Tank

The liquid nitrogen reservoir is a double-casing stainless steel tank. A vacuum is made between these two envelopes in order to avoid a transfer of heat or cold.


Water Chiller Operation

Water Chiller unit is designed to cool the Helium compressor by facilitating a heat exchange water helium oil from the He compressor.

It’s purpose is to send cooling water to a constant temperature of 20°C in the helium compressor exchanger in order to cool:

– The oil of the helium compressor necessary for its recompression,

– Helium from the phenomenon of recompression and actuation of the cryogenic head


Helium Compressor

The Helium compressor acts a Heat Exchanger for the Liquid Nitrogen generator Cold Head. To keep the Cold Head cool while the gaseous Nitrogen is passing through it. Helium is the element that actually will convert the N2 gas to Liquid, because Nitrogen will get converted in liquid form at -197 degree Celsius.



At standard pressure, the chemical element helium exists in a liquid form only at the extremely low temperature of − 270 °C (about  4 K or − 452.2 °F). Hence it is able to perform its function.