Figure 2-19. Basic T750 With Multiple Calibration Gas Mfcs - Teledyne T750 User Manual

M
ULTIPLE
An optional third mass flow controller can be added on the calibration gas stream. When
this option is installed, the T750 has both calibration gas MFCs on the same gas stream,
installed in parallel (see Figure 2-19 and Figure 2-20). The calibrator turns on the MFC
with the lowest flow rate that can accommodate the requested flow and can therefore supply
the most accurate flow control. When a flow rate is requested that is higher than the highest
rated MFC (but lower than their combined maximum flow rating), both controllers are
activated.
EXAMPLE:
•
•
Calibration gas flow rates:
When the third MFC option is installed, the Dashboard parameters that show the MFC
actual and target flows, Cal Flow Actual and Ca Flow Targ, show the sum of the flows of
all the active MFCs. On the other hand, the Dashboard parameter that show the pressure
measurement, Cal Gas Press, shows the pressure for only one MFC, not the sum as it is
assumed that gas pressure is the same for all MFCs.
Instrument Chassis
DILUENT
INLET
DILUENT
Valve
CAL GAS
INLET
GAS INPUT MANIFOLD

Figure 2-19. Basic T750 with Multiple Calibration Gas MFCs

083730750B DCN8606
C S G
ALIBRATION OURCE
Calibrator with one calibration gas MFC configured for 0-5 SLPM:
Maximum gas flow = 5 SLPM
Minimum gas flow = 500
Calibrator with two calibration gas MFCs configured for 0-1 SLPM and 0-5
SLPM:
5.001 to 6.000 SLPM; both MFCs active
1.001 SLPM – 5.000 SLPM; High MFC active;
0.100 SLPM – 1.000 SLPM; Low MFC active
brn
brn
DILUENT
PRESSURE
SENSOR
CAL GAS
PRESSURE
SENSOR
orn
orn
yel
yel
MFC'
AS S
/min
cm 3
brn
Diluent
Mass Flow Controller
Cal Gas
Mass Flow Controller 1
blu
yel
yel
yel
Cal Gas
Mass Flow Controller 2
yel
yel
On Output Panel
EXHAUST
CAL GAS
OUTPUT
blu
45