Excellent for use in the field
Operate at room temperature
Available with arsine and phosphine
Patented G-Cal permeation tubes offer a proven and
repeatable means of generating a desired gas or vapor
concentration. The permeant gas escapes through the
proprietary membrane system and mixes with a carrier gas
at a controlled flow rate to obtain a known mixture in ppm
or ppb. Applications include calibration of gas monitoring
systems and chromatographs, accuracy check of gas
detectors, and generation of known test atmospheres for
a specific application.
G-Cal devices exhibit the lowest temperature sensitivity
among available similar products. The permeation rate of
the polymer used in G-Cal devices changes only 1-3% per
degree C, eliminating the need for a temperature-controlled
chamber.
Over 100 different substances are available, including
arsine, phosphine, and gas phase devices such as CO,
NO, and methane. Available permeation rates range from
less than 200 ng/min to 30,000 ng/min. Each G-Cal device
is individually calibrated and vertified to generate a given
output (ng/min) vs. temperature. A graph which shows
permeation rate vs. temperature from 0 to 50°C is included
with each device.
Description
Temperature Sensitivity
&
G-Cal Permeation Devices
*
Analytical
Components
Systems
VICI Metronics Inc.
US Patent No. 4,399,942
Permeation rates and sizes shown are approximate. Overlapping
may occur.
Device Selection
Devices for most substances are available with various
permeation rates as indicated by the model number digits
in the table at left. Use this formula to calculate the
permeation rate your application requires:
where C is the desired concentration in ppm, F is the carrier
gas flow rate in ml/min, and K is the molar constant from
the substance charts on the next page.
For example, if a concentration of 20 ppm of H
2
S (Model
GC23-700_) is desired with a flow rate of 300 ml/min of
air:
Therefore, G-Cal Model GC23-7003 with a permeation rate
in the range of 5,000 to 14,999 is the appropriate choice.
Permeation rate P in ng/min =
C x F
K
20 x 300
= 8356 ng/min.
0.718
Comparison of G-Cal permeation devices
and Dynacal PTFE permeation devices
20,000
ng/min
5,000
ng/min
6,000
7,000
8,000
9,000
10,000
15°C
20°C
25°C
30°C
35°C
Typical G-Cal device
Typical PTFE device
1
1
/
2
" diameter x 9" long
1" x 4
1
/
2
"
or
1" x 3
1
/
2
"
1" x 4
1
/
2
"
or
1" x 3
1
/
2
"
1" x 6
1
/
2
"
1
1
/
2
" x 6
1
/
2
"
0
1
2
3
4
100 to 2,999
10 to 99
100 to 4,999
5,000 to 14,999
15,000 to 50,000
Model number
(last digit)
Rate range
(ng/min)
Size
(approximate)
Website : www.chromtech.net.au E-mail : info@chromtech.net.au TelNo : 03 9762 2034 . . . in AUSTRALIA