How to Safely Swap a Gas Bottle on Your Caravan

How to Safely Swap a Gas Bottle on Your Mars Caravan

Swapping a gas bottle on your van is a 5-minute job that's safe to do yourself — provided you follow the order. Skip a step and you risk a leak; do it properly and you'll never have an issue.

What You'll Need

  • The replacement gas bottle (right size, in test date)
  • A small spray bottle of soapy water (1 tsp dish soap in water)
  • Adjustable spanner (only if needed — most pigtails are hand-tight POL or quick-connect)
  • Bare hands, not gloves — better feel for fittings

Before You Start

  • Make sure all gas appliances inside the van are OFF — cooktop, hot water, heater.
  • No naked flames or sparks anywhere near the gas locker — no smoking, no camp lighters, no portable BBQs running nearby.
  • Work outside or in a well-ventilated area.
  • Position the new bottle near the locker before you start, ready to lift in.

Step-by-Step Bottle Swap

1. Turn the Empty Bottle OFF at the Valve

Open the gas locker. Find the bottle that's empty (usually the one currently feeding the appliances if you have a changeover regulator and gas just stopped). Turn the bottle valve fully clockwise to OFF.

2. If You Have a Changeover Regulator — Switch It Over First

If you've still got gas in the second bottle, switch the changeover lever so the full bottle is now feeding the appliances. You'll regain gas immediately. Now you can take your time changing the empty bottle.

3. Disconnect the Pigtail

The pigtail (flexible hose) attaches the bottle to the regulator. Connection types:

  • POL fitting — left-hand thread. Unscrew anti-clockwise (looking at the fitting). Hand-tight usually; spanner if needed.
  • Quick-connect — push the collar back and pull. Newer fittings; common on some Mars builds.

Cap the pigtail end with the protective cap if one is fitted, or rest it carefully so the fitting stays clean.

4. Remove the Empty Bottle

Lift it out of the locker. Set it aside.

5. Inspect the Replacement Bottle

  • Check the test date stamp — must be within 10 years.
  • Look for any obvious damage to the valve.
  • Make sure the bottle valve is OFF.
  • Remove the protective cap (if fitted).

6. Install the New Bottle

  • Lift it into the locker and position so the valve faces the regulator.
  • Make sure the bottle is upright and secure in any retention strap or bracket.

7. Connect the Pigtail

  • Inspect the rubber sealing washer inside the POL nut — replace if cracked or perished.
  • Hand-thread the POL nut onto the bottle valve (left-hand thread — turn anti-clockwise looking at the bottle).
  • Tighten firmly by hand, then a gentle nip with a spanner if needed. Don't over-tighten — you're crushing the rubber seal, not metal-on-metal.
  • For quick-connects: push fitting fully home until the collar clicks into place.

8. Slowly Open the Bottle Valve

Open the bottle valve slowly — about a quarter turn at a time. Slow opening lets the regulator equalise without slamming it. A fast open can trigger the excess-flow safety device and shut gas flow off (you'll then need to wait several minutes for it to reset).

Open the valve fully (it normally has a hard stop).

9. Test for Leaks With Soapy Water

This step is essential. Spray soapy water on:

  • The POL/quick-connect fitting between bottle and pigtail
  • The fitting between pigtail and regulator

Watch for bubbles. No bubbles = no leak. Any bubbles forming = leak. If you see bubbles:

  1. Turn the bottle valve OFF immediately.
  2. Wipe off the soapy water.
  3. Inspect the fitting — check the seal, check the connection.
  4. Re-tighten or reseat the fitting.
  5. Re-open the bottle valve slowly and test again.
  6. If it still leaks, do not use the bottle. Lodge a ticket or contact a gas fitter.

10. Test an Appliance

Light a burner on the cooktop briefly to confirm gas is flowing properly. You may hear a hiss for a few seconds while the line repressurises. The flame should be steady and blue.

11. Close Up

Close the gas locker. If you're not using gas immediately, turn the bottle valve OFF again for safety.

What If You Don't Have a Changeover Regulator?

Older or simpler installs may have a single bottle in service. Same process, just no switch step — you simply lose gas supply between disconnecting the empty and connecting the full.

What Not to Do

  • Don't use Teflon (PTFE) tape on POL fittings. POL connections seal on the rubber washer, not the thread. Tape can prevent proper seal and leak.
  • Don't force a fitting. If it won't thread, check thread direction (POL is left-hand) and check alignment.
  • Don't skip the soap test. A small leak you can't smell can still be dangerous.
  • Don't use a damaged bottle. If the valve is damaged, the bottle is dented, or the test date is expired — don't use it. Take it back to the swap point.
  • Don't smoke or have any ignition source nearby. Obvious but worth saying.

If You Smell Gas at Any Point

Stop immediately, turn the bottle off, open everything up to ventilate, and see "I Can Smell Gas" — What to Do Right Now.

One Final Note

Soapy water is the cheapest and most reliable leak test there is. Carry a small spray bottle of it in your van. Use it every time you swap a bottle. It takes 10 seconds and might save your van — or your life.

Related: Gas System 101· "I Can Smell Gas"· Annual Gas Certification


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