LPG Cylinder Storage Rules for Food Trailers UK

Last updated: August 2026

In 30 seconds:

• Propane cylinders live outside the food prep area — in a vented box or locker that is sealed off from the inside of the trailer.
• Always upright, valve uppermost, and strapped so nothing moves when you tow.
• The compartment needs vents top and bottom. Propane vapour is heavier than air, so it sinks and pools if it cannot drain out.
• No electrics, no sparks, no smoking inside or right next to the cylinder space.
• Spare cylinders count too. Your CP44 certificate records how many your unit is signed off for — work to that number.

Not sure how many cylinders you actually need on board? Work it out first with our LPG cylinder run-time calculator, then size the storage around that answer.

Why storage gets people in trouble. Most traders think about the cooking kit and treat the cylinders as an afterthought. Then an environmental health officer or a gas engineer looks at the unit and the cylinders are the thing that fails it.

Why propane sinks. Propane vapour is roughly one and a half times heavier than air. A small leak does not drift away like a smell would — it runs downhill and settles in the lowest space it can find. That is why the bottom vent matters more than the top one.

Why “outside” really means outside. A cylinder compartment has to be sealed from the trailer interior. If a leak can find its way into the serving area, the compartment has failed, no matter how tidy it looks.

Honest summary: the biggest mistake we see is a spare cylinder rolling loose in the back of the van or tucked under a prep bench “just for today”. It is the single quickest way to fail a gas safety inspection and the single most likely thing to hurt someone.

Where LPG cylinders are allowed to go on a food trailer

There are only three acceptable places for a propane cylinder on a mobile catering unit.

• An external cylinder box or locker bolted to the A-frame or chassis — the most common setup on trailers.
• A dedicated internal compartment that is vapour-tight to the inside of the unit and vented directly to open air.
• Standing outside the unit on level ground, upright and restrained, for static pitches where the gas engineer has signed that arrangement off.

Anywhere else is a fail. That includes under counters, inside cupboards that open into the kitchen, in the tow vehicle boot, and behind the serving hatch.

What the compartment itself has to do

• Seal against the interior — a solid bulkhead, no gaps around cable runs or pipe entries.
• Vent low — an opening at floor level so sinking vapour drains straight to outside air.
• Vent high — so the space cannot become an oven in summer.
• Drain to open air — never into an under-floor void, a wheel arch or a closed skirt.
• Keep ignition sources out — no sockets, switches, batteries, inverters or light fittings inside.
• Resist fire — steel construction with sealed joints, not plywood and a tarpaulin.

The purpose-built option: an LPG cylinder storage box

Building a compliant compartment from scratch is possible, but most traders end up buying a box that already does the job. Ours is made in the UK for exactly this use.

LPG Gas Cylinder Storage Box

Quick specs

• Model A: holds 2 × 19 kg cylinders — 1000H × 400D × 700W mm, 27 kg
• Model B: holds 2 × 13 kg cylinders — 800H × 400D × 700W mm, 23 kg
• Outer: 0.9 mm plastisol-coated steel
• Inner liner: 0.9 mm galvanised steel
• Joints: sealed with fire-retardant silicone
• Ventilation: integrated grills top and bottom
• Finish: 50+ RAL colours, hinged front door or top-opening lid
• Price: from £899, cylinder securing kit +£45

Best for trailers, coffee vans and street food units that need a signed-off cylinder space without a custom fabrication job.

What it does

• Keeps cylinders upright and out of the weather
• Vents at both levels so vapour cannot pool
• Gives the gas engineer a compartment they recognise at CP44 time
• Matches the van when you pick the RAL colour

Don’t use it for

• Storing anything other than cylinders — no cloths, no cleaning chemicals, no spare parts
• Mounting inverters, batteries or leisure electrics
• Cylinders larger than the model is built for

Trade-off. The bare box is supplied without fixings. Add the securing kit unless you already have straps and brackets you trust — a cylinder that can move is a cylinder that can shear a hose.

You can see the current build options and colours on the LPG Gas Cylinder Storage Box product page.

Securing cylinders for towing

Storage rules and transport rules are the same rules. The cylinder does not know whether you are parked or doing 55 mph on the A1.

1. Close every cylinder valve before you move, even if the appliances are already off.
2. Stand each cylinder upright, valve at the top. A propane cylinder on its side can pass liquid into the regulator.
3. Strap them individually to a fixed bracket, not to each other.
4. Check the hose has slack but is not trapped by the door or the strap.
5. Latch the box and confirm the vents are clear of mud, leaves and road salt.

Never carry a spare cylinder loose in the cab of the tow vehicle. If you have to move one in a car, it goes upright, restrained, with a window open and the journey kept short.

Spare cylinders and changeover

A spare on board is stored LPG. It follows the same rules as the one you are running: same compartment, same upright position, same restraint, and it counts towards what your unit is certified for.

Full and empty look the same. Mark empties the moment you swap them. A trader hunting for the full one during a lunch rush is a trader taking shortcuts.

Automatic changeover. If running dry mid-service would cost you a queue, an automatic LPG changeover valve switches to the reserve cylinder on its own and shows you when the first one is spent. Ours is fitted with an over pressure shut-off, from £129. It is a fitted part, so it belongs on the gas engineer’s list, not a Sunday afternoon job.

Ventilation, ignition sources and fire kit

Keep the vents clear. Grills get blocked by pressure-washing debris, insulation offcuts and gaffer tape. Look at them weekly.

Keep drains and gullies at arm’s length. Site the unit so the cylinder compartment is not sitting over a drain, gully or cellar hatch. Around a metre of clear ground is the working rule — sinking vapour needs somewhere harmless to go, not a hole to fill.

Keep ignition away. No generators, extension leads, hot plates or cigarette breaks alongside the cylinder space.

Carry the right fire kit. A dry powder extinguisher and a fire blanket, both in date, both reachable without leaning across the cooking line.

Hoses, regulators and the annual check

The cylinder is only as safe as the parts bolted to it.

• Regulator: 37 mbar for propane. That is what commercial mobile catering appliances are built to run on.
• Hose: orange LPG hose to the current British Standard, with the date stamp still readable. Replace on the manufacturer’s interval — commonly five years — or sooner if it is cracked, sticky or crushed.
• Clips and fittings: proper hose clips or crimped ends. Never a jubilee clip on a hose that was designed for a crimp.
• Bubble tester or leak spray: cheap, fast, and the only honest way to check a joint. Never a lighter.

All of it gets inspected when your unit is certified. Our guide to the CP44 gas safety certificate for mobile catering walks through what the engineer looks at and how often you need it. For the wider picture on appliance installation and daily checks, see the gas safety and equipment guide for mobile catering units.

Picking the right cylinder size for the space you have

Storage and sizing pull against each other. A 47 kg cylinder runs longer but is heavy, tall, and needs a bigger box. A 19 kg is easier to lift and swap but you will change it more often.

The practical answer for most trailers is a pair of 19 kg propane cylinders in an external box, one running and one on reserve. It fits the standard box footprint, it is liftable by one person, and swaps are available almost anywhere.

If you are still deciding, our breakdown of LPG cylinder sizes for mobile catering covers vaporisation rate as well as capacity — the bit that catches people out on cold mornings when a small cylinder cannot give up vapour fast enough.

Weekly storage checklist

• Vents clear top and bottom
• Cylinders upright and strapped, no movement by hand
• Hose date stamp readable, no cracks or crush marks
• Joints leak-tested with spray or a bubble tester
• Empties marked and swapped out, not stacked in the corner
• Box interior dry, empty of clutter, latch working
• Extinguisher and fire blanket in date and reachable

Frequently asked questions

Can LPG cylinders be stored inside a food trailer?

Only in a compartment that is sealed off from the trailer interior and vented directly to open air, top and bottom. A cupboard that opens into the serving or prep area does not count, however neat it looks. Most traders find an external box on the A-frame or chassis simpler to get signed off.

How many propane cylinders can I carry on a mobile catering unit?

Your gas safety certificate records the number your unit is certified for, including spares, so work to that figure rather than a number you read online. Adding cylinders beyond what the engineer signed off changes the installation and needs re-certifying.

Can I use butane instead of propane in the trailer?

No. Propane only. Butane stops vaporising properly at around 2°C, so on a normal British trading morning the cylinder simply will not give up vapour fast enough to feed the burners. Butane is for patio and camping use. Commercial mobile catering appliances are rated for propane at 37 mbar.

Do spare cylinders have to be stored the same way as the one in use?

Yes. A spare is stored LPG whether it is full or empty. Same compartment, upright, valve closed, restrained. Empty cylinders still hold vapour and are treated exactly like full ones.

Can I lay a cylinder on its side to fit it in?

Never. Propane cylinders are designed to deliver vapour from the top. On their side they can push liquid propane into the regulator and hose, which is both dangerous and destructive to the appliance. If the cylinder will not stand up in the space, the space is wrong.

Does the cylinder box need to be steel?

It needs to resist fire and contain a leak, which in practice means a steel-lined compartment with sealed joints and integrated vents. Timber and plastic boxes may look the part but will not satisfy an engineer at certification.

What should I do if I smell propane around the cylinder box?

Close the cylinder valves, do not touch any electrics or switches, keep flames away, and let the compartment air. Do not restart trading until a Gas Safe registered engineer qualified for LPG mobile catering has found and fixed the fault.

How often should the LPG hose be replaced?

Follow the date stamp and the manufacturer’s interval, commonly five years, and replace immediately if the hose is cracked, sticky, crushed or chafed. Hoses live outdoors in UV and road salt, so they age faster than people expect.