A bubble tester can be installed instead of a test point. They detect gas flow and provide a visual way of seeing if your gas system has a leak.
(Click on the pictures to enlarge the image.)

To ensure your LPG system is leak free there needs to be a means for testing it. There are two solutions:

1) Have a readily accessible approved test point in the pipework

2) Install a Bubble tester in the gas locker (which allows easy checking of the system at any time without the need for tools or equipment).
A bubble tester must be mounted in the gas locker, they are not allowed in the cabin.

Regulators and high pressure components that are not directly attached to the cylinder valve (e.g a changeover kit) must be secured in a position that protects them from mechanical damage.