For clarification, I didn’t call your thread elementary…
 
I called the using the term “tube” elementary as it could mean the sleeve or the bulb… and the manual used the term “tube”, not you…
 
UV-C rays to not penetrate glass very far at all… but do penetrate quartz quite well… Thus any UV lamp will use a quartz sleeve if they are to have any effect what so ever…
But if the manual said it uses a "glass tube" you had every reason to wonder... and I would be very hesitent to trust a manufacturer who would print such misinformation...