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Chemical collection and stock control for UK schools, universities and hospitals

Nitrogen (CAS 7727-37-9): storage and disposal

Compressed nitrogen is held in cylinders in university, pathology and histology laboratories, usually to feed an instrument or to keep air away from sensitive work. It is a gas under pressure that may explode if heated, and refrigerated forms can cause cryogenic burns or injury. Nothing happens to the gas as it ages, so handling is decided by the cylinder: who owns it and what state it is in.

CAS number
7727-37-9
Form
Gas
Storage class
General
Signal word
Warning
Usual EWC code
16 05 05
  • Gas under pressure pictogramGas under pressure

This chemical is a manual enquiry

This is held as a compressed gas. Cylinders are usually returned to the supplier or handled separately, and they do not go into a laboratory pack.

Held as a compressed or liquefied gas in a pressure container.

It cannot be priced through a form. Please do not open or move it. Call us or send an enquiry and we will talk through the safe next step, which is often a store assessment.

What to do this week

  1. Leave it where it is. If it looks old, crystalline or damaged, do not open or move it and keep people away from the shelf.
  2. Write down the label wording, the rough age and where it is stored, from a safe distance.
  3. Send us those details, and a photo if you can take one without touching it.

Safe storage in a school or lab

In a university lab a nitrogen cylinder usually stands chained to a wall or a bench stand next to the instrument it feeds, with a regulator left permanently in place. That is a reasonable home, provided the chain is actually fastened and the cylinder sits clear of radiators, ovens and direct sun. Spares and part used cylinders are often less well kept: leaning in a corridor or a corner of a store, unchained, with no valve protection. Each needs to stand upright and secured, in the same way as the one in use. Mark which are full and which are finished, because a nitrogen cylinder gives no hint of its contents by weight or look. Never puncture or vent one to tidy a store.

How to tell it has deteriorated

Age does not change this gas, so there is nothing about the contents to look for and a very old cylinder may hold exactly what its label says. What does change is the cylinder. A sound one has a readable supplier label, an intact valve guard, a clean body and a test mark. Look for rust at the base where it has stood on a damp floor, dents, a bent valve or a missing guard. A hiss from a fitting suggests a leak, and it should be reported to the supplier or your site contact. A missing label is the other common fault, since colours and shoulder markings alone are not a safe way to identify a gas.

How it must be disposed of

This does not go through our standard collection route. It is arranged by manual enquiry, and never goes down the drain or into general waste.

It normally leaves the way it arrived, on the supplier's lorry, as most cylinders are their property and go back to them. Pressure containers stay out of lab packs, and this site does not quote for cylinders online, so nothing here applies through the online path. Read the label for an owner and contact them first. Where no owner can be found, send a manual enquiry with a photograph, the wording on the label, the size and its location, and a store assessment is recommended. Leave it upright and secured until advice arrives. Do not vent it or puncture it or try to run it down beforehand. It must not go to scrap, or into a general waste bin or skip.

Waste codes and transport details for Nitrogen
EWC code, laboratory chemicals16 05 05
Hazardous wasteNo

Gases in pressure containers are assessed by manual enquiry, usually with return to the cylinder owner.

The code depends on where the waste came from and what it is mixed with. Use the waste code finder to see why.

Common quantities we collect

Usually held as: cylinder.

Part-used bottles and full containers are both fine. Tell us the size and how many, and an estimate is enough for a first price.

Where it is commonly held

Hazard statements

  • H280 Contains gas under pressure; may explode if heated.
  • H281 Contains refrigerated gas; may cause cryogenic burns or injury.
Precautionary statements
  • P282 Wear cold insulating gloves and either face shield or eye protection.
  • P336+P317 Thaw frosted parts with lukewarm water. Do not rub affected area. Get medical help.
  • P403 Store in a well-ventilated place.
  • P410+P403 Protect from sunlight. Store in a well-ventilated place.

Substance as classified, dilutions may differ.

Questions

We have a cylinder from a supplier we no longer use. Who collects it?

That supplier still usually owns it, so contact them first, even if the account has closed. They can normally arrange its return. If they no longer trade or do not recognise it, send a manual enquiry with a photograph and keep it upright and secured.

Is it safe to run the cylinder down so that it can go as scrap?

No. Do not vent or empty a cylinder to get rid of it, and do not send it to scrap. An apparently empty cylinder is still a pressure container. Close the valve, keep it upright and secured, and ask the owner to take it back.

An old cylinder has rust around the base. Should we still move it?

Do not move it until someone has looked at it. Rust at the base usually comes from standing on a damp floor, and how deep it goes cannot be judged by eye. Keep it secured, photograph it and raise it with the owner or through a manual enquiry.

Guidance only. Check your own risk assessment and your supplier's safety data sheet.

Hazard data source: PubChem GHS Classification, retrieved 31 Oct 2026. Formula N2. EC number 231-783-9.

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