TVOC 2 MANUAL
Ion Science Ltd
Page 6 of 32
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Introduction to TVOC 2
TVOC 2 is a fixed continuous monitor for the detection and measurement of total volatile organic compounds, which
can be dangerous from both a poisoning and explosive perspective. Total VOC’s are detected using PID (Photo ionisation
detection) technology.
TVOC 2 has a number of user selectable features which define its operation and will be application dependent. The user
can define the detection ranges or 0.01 - 10ppm, 0.1 – 100 ppm or 1 – 1,000 ppm (Default); detection units, either ppm
or mg/m
3
.
IMPORTANT:
TVOC 2 can be calibrated on alternative gases to Isobutylene however to ensure it remains within
specification, the correct concentration for the alternative gas must be chosen.
Example: Benzene gas has a response factor of 0.5 which means only half as much concentration is required to produce
the equivalent to Isobutylene.
The ideal gas / concentrations used to set the calibration SPAN are shown below: -
Lower limit
Upper limit
10 ppm range
8 ppm
12 ppm
Isobutylene equivalent
100 ppm range
90 ppm
110 ppm
Isobutylene equivalent
1,000 ppm range
900 ppm
1100 ppm
Isobutylene equivalent
How to calculate alternative concentration of gases for gases other than Isobutylene: -
Calibration
Ideal response
Response
Ideal calibration gas
Gas
for Isobutylene
factor
concentration
Benzene
100
x
0.5
=
50 ppm
Isoprene
100
x
0.9
=
70 ppm
Isobutylene
100
x
1.0
=
100 ppm
Carbon disulfide
100
x
1.4
=
140 ppm
Ethyl acrylate
100
x
2.3
=
200 ppm
For other gas response factors please refer to the Ion Science web site or contact Ion Science Ltd.
https://www.ionscience.com/product-range/search-by-gas/
Warning:
Ignoring these guide lines may result in calibration failure, loss of resolution or loss of range.
The default settings of TVOC 2 are:
Detection range
-
1 – 1000 ppm
Units
-
ppm
TVOC 2 gives a continuous 4-20 mA output which can be integrated into a DCS control system to give an indication of
VOC levels in the operating environment. Note the 4-20 mA output must be externally powered with 8-35 V.
In addition to the 4-20 mA output TVOC 2 has an LCD display showing gas concentration and 4 colour LEDs. LED functions
are as follows:
Green
- is an indicator of TVOC 2’s working status
Red
- is the fault indicator
Yellow x 2
- are calibration status indicators
Please see Calibration for more information on LED status.