make a normal gas mask lockable

I am looking for a solution to lock the gas mask for a certain time, 
a chain around the head with a timer padlock is unfortunately not sufficient, 
I can pull the mask up and take it off, anyone have a creative solution?

when i work from home i like to put these on and then for a certain amount of time that it can't be taken off, 
of course if you tie your hands behind your back you can't get to it, but in this case an office job at home

Yes, it can be done, however the easiest way to keep you from pulling it off your head would be an Open Face lockable hood.

The other way requires a ring, around the tube, and locking it to a collar.
You may also need a locking strap from the collar, behind your head to the top of the mask.
Use D-rings to keep straps in place.