Tanks 80% shut off fill valve with check valve
All GAS IT bottles and gas tanks have a automatic check valve fitting in the 80% shut off fill valve, so should you remove the fill hose or the fillhose gets cut then the check valve in the tank or bottle will see a full pressure drop and automatically shut off.
Don't forget that there is a high possible chance the fill hose will have full pressure liquid LPG in it so when you come to remove the fill hose you need to 100% commit to removing the hose for the check valve in the bottle or tank to shut. If you only open the hose fitting a little way then the liquid will come out, it will freeze the fittings and might then not shut off - plus it will likely empty the tank or the bottle fully.
If you are removing the fill hose we always recommend that you have a the 2 parts from the GAS IT removal kit to hand so that you can shut off the hose ( if your removing the fillpoint ) or the fill valve elbow ( if you removing the fill hose from the bottle or tank. These are our Part number GI-FH-032 & GI-FH-033
Before you do any work on LPG products or anything that has had gas in them its safety, safety safety.
We always recommend getting a trained GAS IT dealer to carry out any LPG work on your GAS IT products because liquid LPG freezes the skin on contact so wear gloves with a coating that stops them getting wet with liquid LPG, wear safety glasses and evena full face mask to stop liquid LPG hitting your face, cover up exposed skin. Watch out for ignition sources from naked flames, electrical connections ( 240 or 12 volt ) and also make sure you are not near open holes or grids as LPG is heavier than air and will find the lowest point and will float on water.