IK-E317-001GB 5
6 CONSTRUCTION DESCRIPTIONS
The detector’s mechanical construction is shown on Figure 1. Its basic element is a detecting optical
module consisting of transmitting and receiving diodes. They are fixed in a holder in such a way that
radiation emitted by the transmitting diode does not reach the receiving diode directly. The
detecting module (holder with diodes) is mounted on a printed board that comprise also a circuit
with the detector’s monitoring processor. The optical module is protected by a labyrinth, damping
external radiation. A wire mesh net prevents irruption of small insects or bigger pieces of dirt. The
whole structure is placed in a black plastic housing consisting of basket, screen and detector casing.
The DUR-40Ex detector is installed in the G-40 base where also detecting line cables are connected
to.
creen
Detecting module
Detector casing
Printed board
M esh
Basket
Laby rinth
Fig.1 DUR-40Ex mechanical structure
7 PRINCIPLES OF OPERATION
The DUR-40Ex is a Tyndall effect optical smoke detector – light scattering on smoke particles. Its
basic element is a detecting optical module consisting of an electroluminescence diode that
transmits radiation and an optical receiving diode. The optical module and surrounding measuring
chamber are protected by a labyrinth which is shaped to dump both external light and radiation
resulting from internal reflexes of the transmitting diode light. When smoke particles enter the
measuring chamber, they reflect the light emitted by the transmitting diode. The reflected light
reaches the optical diode producing photocurrent which is first strengthened and processed and
then analysed by the microprocessor installed inside.
An alarm mode is indicated with red light emitted by a signalling diode installed on the detector
casing. The indicator enables fast localisation of the activated detector and is helpful in periodic
detector’s inspections. In case the detector is installed in a hard to reach space, an additional optical
alarm signal can be obtained by connecting the WZ-31 alarm in an accessible and visible place.
The DUR-40Ex detector has a built-in self-regulation digital system maintaining constant sensitivity to
progressing dirt build-up inside the measuring chamber. After exceeding the pre-set regulation
threshold the detector sends an alarm signal to the control panel.
8 MAINTENANCE INSTRUCTIONS
The DUR-40Ex optical smoke detector should undergo periodic inspections, carried out at least once
in 6 months, to prove that the detector operates correctly and works together with the fire control
panel properly. Those checks are executed using smoke imitating aerosol.
The detector’s long-term utilisation may result in dirt built-up inside its measuring chamber.
