As has been explained above, not with a klinger glass. It wouldn't normally with a UK type glass either. However, I have been on a loco when a glass broke, and the ball valve on the water side did not seat. Obviously, the water flashes straight to steam when released, making it impossible to see or breathe in the cab. Quite disorientating, even on a loco you are well used to. Jacket over the head job to be able to get near it, and a colleague off to A & E to get a scalded hand seen too. If that had happened in a situation where there had been a "cab full", someone could easily have been seriously hurt.