LPG vs Natural Gas for Mobile Catering: Why Propane Wins
Last updated: August 2026
In 30 seconds:
- Mobile catering in the UK runs on propane. There is no mains natural gas pipe at a pitch, a festival field or a layby.
- Natural gas and propane are not interchangeable. The same Parry hob burner gives 5.557 kW on natural gas and 4.351 kW on propane, and needs a different injector for each.
- Propane carries far more energy in far less volume. That burner draws 0.588 m³/hr of natural gas but only 0.178 m³/hr of propane.
- Swapping the fuel without changing the injector is dangerous. Conversion is a Gas Safe registered engineer job, both ways.
- Budget from £150 a year for the gas safety check that keeps you trading, whichever fuel you end up on.
Work out how long a cylinder will actually last you with the LPG cylinder run-time calculator.
Propane supplied at 37 mbar is widely regarded as the standard fuel for UK mobile catering appliances. Natural gas is the standard for buildings. That single split explains almost everything below.
Why does this come up at all? Because natural gas appliances and propane appliances look identical on a supplier’s website. Same stainless steel box. Same burners. Often the model code differs by one letter. People buy the wrong one every week.
What is LPG, exactly? LPG means liquefied petroleum gas. It covers propane and butane. Mobile catering uses propane only. Butane stops vaporising properly around 2°C, so it quits on you on a cold British morning, which is exactly when you are busiest.
Why does the appliance care which one it gets? Because the fuel arrives at a different pressure and a different energy density. The tiny brass injector behind each burner is drilled to suit one fuel. Feed it the other and the flame is either starved or wildly over-gassed.
The honest summary: the expensive mistake is not choosing the wrong fuel. Almost nobody chooses natural gas for a trailer. The expensive mistake is buying a natural gas appliance by accident, because it was cheaper or in stock. Then assuming someone will sort a converter on the morning of the event. Conversion is a booked engineer visit, not a fitting from a box.
Natural gas vs propane: what actually differs
Five things change, and they all matter.
| Natural gas (G20) | Propane (G31) | |
|---|---|---|
| How it reaches you | Piped, metered, fixed to a building | Cylinders you carry and swap |
| Supply pressure | 20 mbar | 37 mbar |
| Appliance category | I2H | I3P or I3B/P |
| Burner injector | Stamped 185 | Stamped 105 |
| Bypass screw | Stamped 85 | Stamped 50 |
| Hose | Natural gas hose | LPG hose, with a regulator |
| Works off-grid? | No | Yes |
The injector numbers are the part worth remembering. A propane injector has a smaller hole than a natural gas one. That looks backwards until you check the pressures. Propane arrives at nearly double the pressure, and it carries far more energy per unit of volume. Smaller hole, higher pressure, same job.
Getting the hose right matters too. Natural gas hose and LPG hose are different parts, and propane also needs a regulator to step the cylinder pressure down. The LPG hose and regulator standards guide covers the specifications and replacement intervals.
The same hob, two fuels: real numbers
The Parry Alpha boiling hob is sold in both versions off the same chassis. The natural gas models are AG2H, AG4H and AG6H. The propane models add a P: AG2HP, AG4HP, AG6HP. Identical steelwork, different injectors. That makes it the cleanest like-for-like comparison on file.
| Per burner | Natural gas G20 at 20 mbar | Propane G31 at 37 mbar |
|---|---|---|
| Heat input | 5.557 kW (18,959 Btu/h) | 4.351 kW (14,846 Btu/h) |
| Gas rate, full | 0.588 m³/hr | 0.178 m³/hr (0.313 kg/hr) |
| Gas rate, low flame | 0.125 m³/hr | 0.041 m³/hr |
| Injector | INJECT185 | LPGINJECT1.05 |
Scale that up and the pattern holds across the range.
| Model | Natural gas total | Propane total | Propane use, all burners on |
|---|---|---|---|
| 2 burner (AG2H / AG2HP) | 11.113 kW | 8.702 kW | 0.627 kg/hr |
| 4 burner (AG4H / AG4HP) | 22.226 kW | 17.404 kW | 1.253 kg/hr |
| 6 burner (AG6H / AG6HP) | 33.340 kW | 26.107 kW | 1.880 kg/hr |
So the natural gas version is more powerful? On paper, yes. Around 21% more heat input per burner. In a food trailer that is irrelevant, because you cannot connect it to anything. A 17.4 kW propane four-burner boils stockpots perfectly well.
The propane kg/hr column is the useful one for trading. A four-burner propane hob with every burner flat out uses 1.253 kg an hour. A 47 kg cylinder therefore gives you roughly 37 hours of absolutely everything on, which nobody ever does. Real service is closer to two burners on low and two on high, so most traders get a week or more out of a cylinder. The LPG cylinder sizes guide covers which bottle suits which setup.
Why propane wins for mobile catering
It travels with you. A cylinder goes where the trailer goes. Mains natural gas is a fixed connection to a building with a meter on it. You cannot take a meter to a county show.
It works with no infrastructure at all. Pitches, fields, car parks and street markets have no gas supply. Many have no mains electricity either. Propane plus a generator is the whole off-grid kitchen.
It stores dense. That 0.178 m³/hr figure is the point. Propane is stored as a liquid under modest pressure. It expands to vapour as you draw it off, so a bottle you can lift holds days of trading.
It works in the cold. Propane keeps vaporising down to around minus 42°C. Butane gives up around 2°C. For outdoor trading through a British winter, propane is the only sensible answer.
The whole market is built for it. Commercial mobile catering appliances are supplied for propane at 37 mbar as standard. Fryers, griddles, hobs, oven ranges, bain maries and water boilers are all specified that way, so spares, hoses, regulators and engineers are easy to find.
If you are fitting out from scratch, the how to convert your food van to LPG guide walks through cylinder location, pipework and ventilation.
Where natural gas genuinely does win
It would be dishonest to pretend propane wins everywhere. If you have a fixed site, natural gas has real advantages.
- Cheaper per unit of heat. Piped natural gas is normally the cheaper fuel per kWh in the UK.
- It never runs out mid-service. No cylinder change at the worst possible moment.
- No handling. No lifting 47 kg bottles, no delivery schedule, no storage cage.
- More heat from the same appliance. Roughly 21% more on the Parry range above.
- No cylinder storage rules to satisfy. One less compliance item on a fixed site.
So if you are opening a unit, a dark kitchen or a permanent takeaway, ask about natural gas. If the kitchen has wheels, it is propane.
Buying the right version first time. Check the model code before you order, not after. The propane versions of most ranges carry a P, an LPG or a G31 marker in the code. Choosing between models? The best LPG hob for mobile catering buying guide and the best LPG oven range guide both list propane-specified units only.
Can you convert an appliance between the two?
Often, yes. Many commercial appliances are designed to be converted, and manufacturers sell kits both ways. The Parry Alpha hobs are a good example of what a kit actually contains.
- A burner injector per burner. Natural gas to propane swaps INJECT185 for LPGINJECT1.05.
- A bypass screw per tap, which sets the low flame. Stamped 85 for natural gas, stamped 50 for propane.
- A new data label, so the appliance is correctly marked for the fuel it now burns.
- Written conversion instructions for the engineer.
Three things to be clear about before you assume conversion is the answer.
It is engineer-only work. The manual is explicit that conversion should be carried out by a Gas Safe registered engineer. That engineer needs LPG on their registration, not just natural gas.
Not every appliance can be converted. Some are single-fuel by design. The data plate and the manual tell you. If there is no conversion section and no kit part number, treat it as not convertible.
The output changes. Converting a natural gas appliance to propane lowers its rated heat input, on the Parry range by roughly a fifth. Size for the propane figure, never the natural gas one on the brochure.
How to check which fuel your appliance is set for
Ten minutes with a torch settles it. Do this before you book an engineer, and before you buy anything second hand.
Step 1: Find the data plate
It is usually a small metal or foil plate on the rear panel, under the base, or behind the kick plate. Photograph it now so you never have to crawl behind the unit again.
Step 2: Read the gas category
I2H means natural gas. I3P or I3B/P means LPG. If the plate lists both, it is a convertible appliance and the marker or label tells you which fuel it is currently set for.
Step 3: Read the supply pressure
20 mbar is natural gas. 37 mbar is propane. This one line resolves most arguments on its own.
Step 4: Check the G number
G20 is natural gas. G31 is propane. G30 is butane, which you should not be running in a food trailer.
Step 5: Compare the heat input to the brochure
If the plate says 22.226 kW and the propane brochure says 17.404 kW, you are holding the natural gas version. A mismatch here is the clearest warning sign there is.
Step 6: Have an engineer confirm it before first use
A Gas Safe registered engineer will check the burner pressure at the test point and read the flame picture. That is the only reliable proof, and it feeds straight into your certificate.
Once it is signed off, keep it that way with the LPG maintenance and safety check schedule.
What it costs to get this right
Conversion pricing varies by appliance and by engineer, so get a quote rather than a rule of thumb. The certification side is more predictable.
- Conversion kit: priced per appliance by the manufacturer, and normally per burner.
- Engineer time to convert and recommission: quoted per visit.
- Mobile catering gas safety certificate: from £150 to £350, commonly with £25 to £40 per additional appliance.
- Ongoing certification: budget from £150 to £250 a year.
Most event organisers and councils expect to see a current certificate before you trade. The CP44 gas safety certificate guide explains what the inspection covers and how often it is typically required.
Six mistakes worth avoiding
- Buying on price without checking the model code. The natural gas version is often the cheaper listing because demand is lower.
- Assuming a regulator converts the appliance. A regulator sets pressure. It does not change the injector, and the injector is the appliance.
- Reusing the wrong hose. Natural gas hose and LPG hose are different parts, and propane needs a regulator as well.
- Sizing off the natural gas kW figure. Propane output is lower on the same chassis. Plan your service around the propane number.
- Converting it yourself. Beyond the safety issue, uncertified work will fail your inspection and can invalidate insurance.
- Trying butane because it was in the shed. It fails in the cold, and commercial appliances here are specified for propane.
Frequently asked questions
Can I run a natural gas appliance on propane?
Not without converting it first. A natural gas appliance has larger injectors sized for 20 mbar, so feeding it propane at 37 mbar badly over-gasses the burners. That means a dangerous flame, sooting and a failed inspection. A Gas Safe registered engineer with LPG on their registration fits the conversion kit and recommissions the appliance.
What pressure does propane run at in UK mobile catering?
37 mbar. Commercial mobile catering appliances are specified for propane at 37 mbar, and the regulator on the cylinder sets that pressure. Natural gas appliances run at 20 mbar instead. The figure is printed on the appliance data plate, so you can confirm it in seconds without tools.
Is propane cheaper than natural gas?
No. Piped natural gas is normally cheaper per kWh in the UK. Propane wins on portability rather than price. For a trailer that is the only comparison that counts, because there is no pipe to connect to. On a fixed site the cost gap is worth taking seriously.
Can I use butane instead of propane?
No. Butane stops vaporising properly around 2°C, so it fails on cold mornings and through the winter, which is when outdoor trading is hardest. Commercial mobile catering appliances are specified for propane at 37 mbar. Butane belongs on patio heaters and camping stoves, not in a food trailer.
How do I tell whether an appliance is natural gas or propane?
Read the data plate. I2H, G20 and 20 mbar mean natural gas. I3P or I3B/P, G31 and 37 mbar mean propane. Cross-check the stated heat input against the manufacturer’s figures, because the propane rating is lower on the same chassis. An engineer confirms it at the test point.
Who is allowed to convert an appliance from natural gas to LPG?
A Gas Safe registered engineer, and specifically one whose registration covers LPG and commercial catering appliances. Natural gas qualification alone is not enough. The engineer fits the manufacturer’s kit, updates the data label and recommissions the appliance, then that work supports your gas safety certificate.
Do I need a different hose for propane?
Yes. Natural gas hose and LPG hose are supplied as different parts, and propane also needs a regulator to step cylinder pressure down to 37 mbar. Hoses have a replacement interval as well, typically five years, and inspectors do check the date. Fitting the wrong hose is a common inspection failure.
Does converting an appliance change how powerful it is?
Yes, and it is worth planning for. On the Parry Alpha hobs, each burner drops from 5.557 kW on natural gas to 4.351 kW on propane. A four-burner unit goes from 22.226 kW to 17.404 kW, around 21% less. Size your kit from the propane figure, not the brochure headline.
The short answer
If your kitchen moves, you are on propane, and the only real decision is cylinder size and how many you carry. If your kitchen is bolted to a building, price up natural gas properly, because it is usually cheaper to run.
What you should never do is treat the two as the same fuel with a different label. They arrive at different pressures, through different hoses, into different injectors, and they produce different heat. Check the data plate, buy the version that matches your setup, and let a Gas Safe registered engineer sign it off.