Secure the on/off valvel on an oxygen tank

I'm on oxygen 24/7, and have to take two tanks with me any time I go out, as I am on too high a liter flow for just one tank to last me long enough. As you can see in this picture, the on/off valve on the tanks is a flip-lever, and if the tank is laying on the floor or the seat in the car, it can be flipped up accidentally very easily, turning the tank on. When this happens with no gauge on the tank, all the oxygen can drain out in just seconds---for me, this is a catastrophe!

I tried taping it closed with all kinds of tape, but they all left sticky residue behind or else the tape wasn't strong enough to hold the lever in the closed position. sugru to the rescue!

Thank you for inventing sugru!

Laurel from South Carolina, USA