TVOC 2 MANUAL
Ion Science Ltd
Page 11 of 32
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Installation
Location
There are many variables involved in defining the optimum location for a gas detector. Obvious though it may sound,
the most important rules are:
•
A detector will not detect gas unless gas actually reaches the detector.
•
TVOC 2 should be mounted in the location most likely to detect gas.
•
TVOC 2 must be mounted vertically with the sensor underneath the case. This avoids water, dust and debris
blocking the access to the detector cell.
•
If possible, mount TVOC 2 near the ceiling to target VOC gases that are lighter than air or just above floor level
to detect VOC gases that are heavier than air.
•
Mount TVOC 2 in an area that has good air circulation. Restricting natural air current may result in delayed
detection.
•
Never mount TVOC 2 in direct sunlight or over a heat source such as a radiator. This may cause the unit to
exceed its certified working temperature range.
•
Do not mount TVOC 2 in areas likely to flood.
•
Mount TVOC 2 units in locations that are easily accessible for servicing.
•
Percentage variations in the composition of air (78% Nitrogen, 21% Oxygen and 1% Argon) may affect the
detected signal.
Please refer to the technical specifications of the instrument under Technical Specifications of this manual before
beginning a TVOC 2 installation.
Cable and gland requirements
The screw terminal sockets for connecting wires in the TVOC 2 accept wires of 0.5mm
2
to 2.5mm
2
Cross-
Sectional Area (CSA)
Screened cables for both power and signal out are necessary to achieve EMC compliance. Cable screens must
be terminated at both ends for them to be effective in achieving electromagnetic compatibility (EMC). The
screens should be terminated to the TVOC 2 enclosure using EMC compatible cable glands. It is important for
an EMC compatible gland to make electrical contact to the enclosure. This is usually done using a serrated
washer or EMC lock nut that bites through the paint making electrical contact. EMC lock nuts have been
provided. These locknuts are orientation specific the points should be facing against the case in order to cut
through the paint during tightening.
Two M20 cable glands and one blanking plug have been supplied as standard to ease installation in most
circumstances. These parts will not be appropriate for all applications, so they should be used at the discretion
of the installation engineer. It is recommended that the manufacturer’s instructions are followed for the gland
and blanking plug installation. The M20 blanking plug has been included to enable installations using a single
cable entry (for example a three-wire system) to be implemented.
While Ion Science cannot recommend the cable gland suitable for every application the following information
may be useful to the installation engineer for the selection of the appropriate type:
•
For intrinsically safe operation using safety barriers, the only requirements on the cable glands are
that they are better than IP20 rated. This may seem extraordinary however, where the power is safely
limited to the TVOC 2 it is intrinsically safe so does not rely on the prevention of dirt or moisture into
the enclosure.
•
For safe operation in Zone 2 without safety barriers, cable glands must be ATEX or IECEx rated (Ex e,
Ex n or Ex d) and at least IP54.
Installation of the TVOC 2 depends on preferences of the installer, intrinsically safe operating legislation and
the application.
Ion Science suggests connecting the screens from cables via a gland as shown on the diagrams and under Installation
Section of this manual. There may however be technical circumstances where connection to the PCB is necessary.
