Videotec EXH Bedienungsanleitung Seite 9

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. IP66
protection is also ensured by two Ex d 3/4" GAS
IP66 ATEX cable glands, in compliance with the
housing markings, which are for insertion of service
cables with a diameter of from 14mm to 17mm.
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.
Ge AR 2 sides - 2mm thick
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Wavelength (µm)
Fig. 02 The graph shows the visible spectrum for the window.
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 +24Vdc).
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).
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