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

Propane (CAS 74-98-6): storage and disposal

Propane is a liquefied fuel gas supplied in cylinders, found in schools and colleges that run burners without mains gas and in university labs and workshops. It is classified as extremely flammable and is held under pressure. Because the vapour is heavier than air, where a cylinder stands matters as much as how it is secured. Most cylinders go back to the gas supplier, and others need a manual enquiry.

CAS number
74-98-6
Form
Gas
Storage class
Flammable
Signal word
Danger
Usual EWC code
16 05 04*
  • Flammable pictogramFlammable
  • 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

Extreme flammability decides where a propane cylinder stands: somewhere well ventilated, away from ignition sources and oxidisers, and never below ground level. The vapour is heavier than air and will run along a floor and settle in a cellar or pit, so airflow low down matters more here than it does for lighter gases. Keep it upright, which holds the liquid away from the valve, and secured so it cannot tip. A cylinder feeding a school burner line should sit out of the sun and clear of boilers or heaters, because it may explode if heated. Acids and corrosive stock belong elsewhere, as their fumes attack seals and fittings. Never puncture or vent it.

How to tell it has deteriorated

Flaking paint and rust at the foot ring are the marks to look for on a propane cylinder, since it often stands on a damp floor. After that, check for a faded hire label and a bent valve or a missing valve cap. The gas itself does not age and gives few visible signs, so an old cylinder can still be close to full. Fuel grade propane carries an added smell, which means a gas smell at floor level suggests a leak. Frost on the valve when nobody is drawing gas points to escaping liquid cooling as it turns to vapour. Either one needs reporting straight away, with ignition sources kept clear and hands off the valve.

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.

Under code 16 05 04*, a propane cylinder counts as gas in a pressure container holding a hazardous substance, whatever level is left inside. In practice ownership matters more than the code. Most cylinders belong to the gas supplier and return to them, so look for a supplier name and ask them to take it back. The harder cases are cylinders from a supplier no longer trading, or one bought for a field project and forgotten. Those go to a manual enquiry with the markings, the rough size and where it stands. A lab pack is not an option for pressure containers, it is not quoted online, and a store assessment is recommended. Until advice comes it stays upright and secured. It must not go in a skip, and nobody should vent or puncture it.

Waste codes and transport details for Propane
EWC code, laboratory chemicals16 05 04*
Hazardous wasteYes

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.

Do not store with

  • OxidiserOxidisers can ignite flammable materials or make a fire far more intense.
  • AcidOxidising acids can ignite flammable materials, and acid fumes attack containers and seals.
  • CorrosiveA leak of corrosive stock can break down flammable containers and feed a fire.

Named chemicals to keep apart

  • Acetic acidOxidising acids can ignite flammable materials, and acid fumes attack containers and seals.
  • Calcium hypochloriteOxidisers can ignite flammable materials or make a fire far more intense.
  • Hydrochloric acidOxidising acids can ignite flammable materials, and acid fumes attack containers and seals.
  • Hydrogen peroxideOxidisers can ignite flammable materials or make a fire far more intense.
  • Nitric acidOxidising acids can ignite flammable materials, and acid fumes attack containers and seals.
  • Potassium nitrateOxidisers can ignite flammable materials or make a fire far more intense.
  • Potassium permanganateOxidisers can ignite flammable materials or make a fire far more intense.
  • Sulfuric acidOxidising acids can ignite flammable materials, and acid fumes attack containers and seals.
Show 2 more
  • Thionyl chlorideA leak of corrosive stock can break down flammable containers and feed a fire.
  • Zinc chlorideA leak of corrosive stock can break down flammable containers and feed a fire.

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

  • H220 Extremely flammable gas.
  • H280 Contains gas under pressure; may explode if heated.
Precautionary statements
  • P203 Obtain, read and follow all safety instructions before use.
  • P210 Keep away from heat, hot surfaces, sparks, open flames and other ignition sources. No smoking.
  • P222 Do not allow contact with air.
  • P280 Wear protective gloves, protective clothing, eye protection and face protection.
  • P377 Leaking gas fire: Do not extinguish, unless leak can be stopped safely.
  • P381 In case of leakage, eliminate all ignition sources.
  • 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

Can a propane cylinder stay inside the prep room?

That depends on the store assessment and what the gas supplier advises for the size you hold. It should never go below ground level, because the vapour is heavier than air and would settle there. Wherever it stands, it needs ventilation low down and no ignition sources nearby.

How can we tell how much propane is left in a cylinder?

A gauge, if fitted, tells you little, because pressure depends mainly on temperature while any liquid remains. Suppliers judge contents by weight. Assume a used cylinder still holds liquid or vapour and remains extremely flammable, and never release what is left to find out.

The cylinder is years old. Does propane go off?

No, propane does not break down in a sealed cylinder, so age does not make it less flammable. What changes is the cylinder itself: rust at the foot, a worn valve and test markings that are long out of date. Report those to the supplier rather than connecting it.

Could we just run an old cylinder down on a burner to get rid of it?

No. A cylinder of unknown age or condition should not be connected to anything, and it should never be burned off or vented to empty it. Even a cylinder that feels light still counts as a pressure container, so the supplier or a manual enquiry remains the route.

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 C3H8. EC number 200-827-9.

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