Live T Switch - Siemens Maxum II PD PA AP Service Manual

Valves

4.7 Live T Switch

4.7 Live T Switch
The Live T Switch is a valve-less switch that can be used in place of a valve for switching
columns. The Live T switch is virtually maintenance free since it has no moving parts, no
temperature limitations and the sample only comes into contact with metal parts inside the
switch. It can be used for heartcut and backflush functions.
The Live T Switch is essentially a tube with special built in air vents that are used to control
carrier flow through the tube. Carrier gas is connected to the vents. Carrier gas pressure at
the vents is adjusted such that carrier sample flow can be either stopped, diverted, or allowed
to pass unimpeded through the switch,
Example Application
The following is an example of an actual application using the live tee. Actual flows and
pressures are indicated and chromatograms are provided to illustrate the set up process.
P
A
Injector
Pre Column
Split and
Backflush
Vent
Figure 4-36 Live Tee Switch Example Application
Switching Configuration:
Pre Column:
Main Column:
Oven Temperature:
100
Pm (+)
Pm (-)
NV Purge
NV Cut
Cut Vent
to FID
Purge Vent
to TCD
Main Column
To FID
Split Vapor Injection
Backflush To Vent With Heartcut (Cut Vent Flow To FID)
Purge Flow to ITC (TCD)
50 m, 0.32 mm id, 1.2 um, Carbowax FSOT
50 m, 0.32 mm id, 5 um, ALOX Na2SO4 FSOT
100°C
Maxum II Valves and Oven Components
Service Manual, 10/2018, A5E42019844001