What is nitrogen used for in hospitals?

Driving surgical tools

ISO 7396-1:2016 includes nitrogen for driving surgical tools in the scope of medical gas pipeline systems, and ISO 9170-1:2017 covers terminal units for the supply and disposal of nitrogen and air for driving surgical tools. HTM 02-01, the NHS England guidance (2026 edition), says that where nitrogen is available on site it may be used as an alternative source of supply to 700 kPa surgical air. Its Table 2 groups the two as surgical air/nitrogen at 700 kPa, with a test flow of 350 L/min in orthopaedic and neurosurgical operating rooms and 100 L/min elsewhere; surgical tools typically need flows of up to 350 L/min at 700 kPa at the point of use.

HTM 02-01 notes that BS EN ISO 5359 gives the connectors for nitrogen for driving tools and that the body of the NIST connector should form the wall outlet. It also lists a pipeline identification for surgical nitrogen. Where nitrogen powers tools, the guidance asks for the potential for oxygen depletion to be considered and for additional environmental monitoring in areas of high nitrogen use. It also notes that surgical air use is declining with the introduction of battery and electrically powered tools.

In Canada, CSA Z7396.1:22 lists nitrogen NF as a medical support gas, alongside instrument air, separately from the medical gases. A 2025 British Columbia training textbook (SkilledTradesBC) on CSA testing gives a concentration of at least 99% at the outlet for nitrogen and a terminal unit pressure drop limit of 70 kPa for nitrogen, against 30 kPa for the other medical gases.

Liquid nitrogen

HTM 02-01 (2026) says liquid nitrogen should be managed and controlled in accordance with the requirements for medical gases. It is supplied in mobile dewars and decanted for distribution to the points of use. It is primarily used for cryotherapy (cryosurgery), which freezes and destroys abnormal tissue, and also for the cryopreservation of biological samples. Its storage needs a risk assessment that considers asphyxiation hazards.

Brazing and pressure testing

Oxygen-free nitrogen (OFN) is also used when the pipelines are built. HTM 02-01 asks for all medical gas pipelines to be brazed with OFN as an internal inert gas shield, to prevent oxides forming inside the pipes and fittings, and for the carcass pressure tests to be performed with nitrogen, so that remedial action can be taken immediately in the event of a leak or cross-connection. The oxygen content of the ambient air should be monitored when brazing in a confined space, and the contractor and site engineer should keep a record of the nitrogen cylinders on site, kept separate from medical gas cylinders at all times. See why pipes are brazed with nitrogen.

Ultra Controlo lists single-stage cylinder pressure regulators for oxygen, nitrogen and CO2 cylinders among its pipeline accessories.