In practice, there are many applications where it is necessary to connect hard-walled tubing (e.g. made of PTFEGlossaryPTFEPolytetrafluoroethylene , PFAGlossaryPFA Perfluoroalkoxy , FEPGlossaryFEPTetraflouroethylene-Perflouropropylene) or tubes (e.g. made of glass, metal, plastic) with devices with GL threadGlossaryGL threadGlass thread (glass thread). BOLA Laboratory Screw Joints are ideal for making these connections.
Each laboratory screw joint consists of a screw cap with a female GL threadGlossaryGL threadGlass thread and bore as well as three inner parts: v-ring, tapered ring and sealing ring.
Assembly can easily be made by hand:
First, the inner parts are pushed on the tubing. After that, the tubing has to be put into the counterpiece and the screw cap has to be tightened. The screw cap presses the sealing ring and tapered ring tightly on the counterpiece. At the same time, the v-ring is compressed and the tubing is fixed tightly. The connection is absolutely tight and even suitable for vacuum. The laboratory screw joints for GL 14, GL 18 and GL 25 resist pressures of max. 10 bar at room temperature.
It is easy to choose the suitable laboratory screw joint:
First of all, the outer diameter of the tubing or tube and the size of the GL threadGlossaryGL threadGlass thread to which the laboratory screw joint shall be connected have to be determined. The size of the GL threadGlossaryGL threadGlass thread corresponds to the outer diameter of the thread, i.e. a GL 25 thread has an outer diameter of 25 mm. Further assistance for the determination of threads can be found in our technical appendix.
Also the application is decisive: Will there be temperatures of more than +150°C? If so, the BOLA HT Laboratory Screw Joints (page 57), which also provide a good chemical resistance, are the right choice. Or is it more important to have a very high chemical resistance? Then you have to choose BOLA Laboratory Screw Joints made of ETFE (red). These can be used up to temperatures of +150°C.
For big flexibility, all screw caps and inner parts are available separately.
BOLA Swivelling Screw Fittings for GL threads or ground joints are ideal for fixing all kinds of probes, tubes or hard-walled tubing safely in a specific angle. It is possible to position supply tubes or probes independently from the angle of the neck.
Damages of supply tubes or probes due to collision with the stirrer shaft can be avoided.