Permeation Tube Calculation - Teledyne T700 Operation Manual

Getting Started
Note

3.3.4. PERMEATION TUBE CALCULATION

72
The name of the gas produced by the permeation tube generator MUST be
different from the name of any bottle connected to the calibrator.
SETUP X.X PERM TUBE 1:10.0 NGM NO2
0 1 0 .0
4. Enter the gas flow through the permeation tube. This should be done with the flow
standard connected at the outlet of the perm tube oven.
SETUP X.X PERM TUBE 1:0.105 LPM
0 .1 0 5
The permeation tube concentration is determined by the permeation tube‟s specific
output or elution rate (which is normally stated in ng/min), the permeation tube
temperature (C) and the air flow across it (slpm). The elution rate of the tube is
normally stated at an operating temperature of 50°C and is usually printed on the tube's
shipping container. By design, there is nominally 100 cm3/min of air flow across the
tube and the tube is maintained at 50°C. The output of the calibrator is the product of the
elution rate with the total of the 100 cm3/min through the generator and the flow of
dilutant gas.
The temperature is set at 50.0C. Check SETUP-MORE-VARS and scroll to the IZS-
TEMP variable to verify that the temperature is properly set. It should be set to 50C
with over-and-under temperature warnings set at 49C and 51C. There is a 105
cm3/min flow across the permeation tube at all times to prevent build-up of the gas in
the tubing.
This permeation tube source gas is diluted with zero air to generate desired
concentration of the specific gas. The calibrator‟s output concentration (gas
concentration) can be calculated using the following equation:

P Km

C
F
Where:
P = permeation rate, ng/min @ 50C.
24 . 46
Km = , where 24.46 is the molar volume in liters @ 25C
MW
and MW is the molecular weight.
760mmHg . Km for SO
1.436.
F = total flow rate (sum of 100 cm
Teledyne API – Model T700 Dynamic Dilution Calibrator
NGM NO2 ENTR
ENTR
= 0.382, NO
2
3
/min and diluent flow), LPM.
EXIT
EXIT
= 0.532, H S = 0.719, and NH
2 2
06873E DCN7106
=
3