This piece is similar to the corresponding CG-1239 model, but vacuum jacketed to improve efficiency. The thermometer bulb and stem serve as column packing. Upper hose connections are for cooling lines and the lower connection is for connetion to vacuum or inert atmosphere. Available with optional Vigreux indentations to improve efficiency.
The 14/20 lower joint size versions accept a 1" immersion 7/12 or 10/18 thermometer, while the 24/40 lower joint versions accept a 2" immersion, 10/30 or 14/20 thermometer.
Application note: Some vacuum distillations need to be performed at a specific pressure rather than full dynamic vacuum. To maintain a relatively low vacuum (~2-50 torr), once can use an adjustable bubbler such as item #AF-0513-A-21 as a low-tech vacuum control (manostat). For those situations where you need to operate at pressures as high as 760 torr or want to avoid the use of mercury (a good idea), consider a Mano-Watch™ vacuum controller/monitor, item #20900-A.