Ion Science TVOC - Manual (Page 11)

TVOC MANUAL Ion Science Ltd
Page 11 of 32
Unrivalled Detection. www.ionscience.com
Installation
Location
There are many variables involved in defining the optimum location for a gas detector. Obvious though it may
sound, the most important rule is:

A detector will not detect gas unless gas actually reaches the detector.

TVOC should be mounted in the location most likely to detect gas.

TVOC must be mounted vertically with the sensor underneath the case. This avoids dust and debris
blocking the access to the detector cell.

If possible, mount TVOC 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 in an area that has good air circulation. Restricting natural air current may result in
delayed detection.

Never mount TVOC in direct sunlight or over a heat source such as a radiator. This may cause TVOC
to exceed its certified working temperature range.

Do not mount TVOC in areas likely to flood.

Mount TVOC ’s in areas 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 installation.
Cable and gland requirements
The Screw terminal sockets for connecting wires in the TVOC accept wires of 0.5mm
2
to 2.5mm
2
C.S.A.
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 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 entry cable (for example a three wire system) to be implemented.
While Ion Science can not recommend the cable gland suitable for every application the following
information may be useful to the installation engineer for the selection of the appropriate cable gland.

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 it is intrinsically safe so does not rely on the
prevention of dirt or moisture into the enclosure.

For intrinsically safe operation in Zone 2 without safety barriers, cable glands must be ATEX
or IECX rated (Ex e, Ex n or Ex d) and at least IP54.
Installation of the TVOC 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.