Someone use oxygen propane torch to vacuum sealing off glass tube.Does it work well? However you would really need a oxygen-hydrogen torch because the melting point is much higher. Oxygen-propane torches can just about soften quartz,but not melt it sufficiently for sealing off.
If you need high vacuum quartz sealing effect,the whole necessary machines should be included oxyhydrogen generator,oxygen hydrogen torch,rotary vacuum sealing device,mechanical pump. Some accessories such as 1m Stainless corrugated pipe with KF25 adapter,flanges are connected between mechanical pump and rotary sealing device.
What is the vacuum level required? What kind of pump?
It depends what sort of vacuum you want to end up with inside the tube. The molten glass is very soft and will start collapsing even under very poor vacuums, say half an atmosphere. Final pressures used could be anything from a few tens of Torr for a gas discharge tube, down to 1E-6 torr, for a thermionic tube.

 

How does quartz glass tube connect with rotary vacuum sealing device?
You should put the quartz glass tube into casing and then put on the seal.Secondly,you can connect with another part of casing on the rotary device.
 

Before sealing quartz tube,you can turn on oxyhydrogen generator firstly. When the pump is power on,you can ignition the oxyhydrogen torch. We use hydrogen and oxygen flame torch to evenly heat the middle of the quartz glass tube, and gradually soften inside glass tube to form the gourd or fillet shape. At the same time, the glass tube is filled the nitrogen gas to separate it from the air under vacuum pressure.