Videotec EXHC series, Instruction Manual

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7
4.1.2 Version with glass protection
device
The EXH series of explosion-proof housings has a
version with a glass protection device, installed on
the front opening of the housing. It comprises a
flange for linking with the housing, a closing flange
and a central, explosion-proof body containing a
strong, transparent glass, a 24Vdc motor, two winders
and transparent Mylar film, installed in front of the
glass.
The motor uses 4 bevel gears to pilot a winder for
recovering dirty film, while the other winder issues
clean film. The motor is remotely controlled by a two-
wire ON-OFF contact (one common and one +24Vac/
Vdc).
h
The control unit for the glass protection
device is supplied by the customer.
The transparent Mylar film can be fed forward about
350 times.
When the film is dirty the operator starts the motor,
so that the film is fed forward until a clean image is
obtained (to completely replace the dirty film in one
step, about 50mm of clean film should be fed).
The end of the tape is marked by printing on the last
50cm of film.
Film feed can also be started automatically by a
timing device if a suitable control system is used (this
is not supplied).
To change the film, see the VIDEOTEC spare part
handbook (code OEXMYLAR).
4 Identification
4.1 Product description and type
designation
The EXH series explosion-proof housing has been
designed for use with cameras operating in industrial
environments in which there may be an explosive
atmosphere due to gas, vapours, mists, or air or
powder mixtures.
EXH housings comprise solid, cast Anticorodal
aluminium alloy from the AlSi7Mg EN AB-42000
group, the exact chemical composition of which is
defined in the UNI EN 1706 standard.
Depending on the model, all parts are powder-
painted and oven-cured or treated with special
coatings giving excellent resistant to UV light, to salt
spray and to atmospheric pollutants.
The camera body comprises a cylindrical tube, with
a flange that houses a strong, transparent glass;
opposite to the glass there is another flange that, as
well as closing the cylinder, also supports the plate to
which the camera is to be attached.
The housing has two holes for 3/4" NPT cable glands.
The cable glands must be selected according to what
is indicated by the EN/IEC 60079-14 Standard.
These cable glands guarantee an IP66 protection
level.
j
We recommend using VIDEOTEC cable
glands or equivalent ( Tab. 01, page 14 ).
4.1.1 Version for thermal imaging
cameras
When using thermal imaging cameras, which are able
to detect heat emission, a special filter on the front
of the housing should be used.This housing differs
in that it has a window made mainly of germanium,
which guarantees the same strength and security
properties as those for standard glass. Range of
application from 7.5 to 14µm.