Duct Smoke Detector KRM®
Fire Protection | Data sheet No. 41300 | Version 06-2012 | 1 | 9
Technical Data
Sensor: Scattering RM 3.3 (ALK-E)
Supply voltage KRM-1: 230 V AC ± 10 %, 50/60 Hz
Supply voltage KRM-2/KRM-2-MOD:
24 V AC/DC +15 % / -10 %
Rated current: KRM-1: 30 mA
KRM-2/KRM-2-MOD: 120 mA
Relay outputs: oating
Alarm relay locked: 1 changeover contact, 8 A,
250 V AC or 24 V DC
1 NC, 8 A, 250 V AC or 24 V DC
Contamination relay:
1 NC contact, 6 A, 250 V AC or 24 V DC
Operating temperature:
-20 °C – +50 °C
Permissible ow:
1 – 20 m/s
Permissible humidity:
10 – 95 % non-condensing
Protection class:
IP54, IP65 with WDG
(water resistant housing)
Certication/approvals: VdS approval G210059
according to FprEN54-27
LED display:
% contamination level ashes
at > 70 %
LED in housing:
green operating
blue lack of air ow
yellow failure, electronics,
smoke detector defective,
low voltage
red smoke alarm, including
contamination > 99 %,
ashes at attempts to release
when the sensing chamber is
not empty
Adapter housing: ABS
Air measuring tube:
Aluminium / plastic
shortest length 160 mm
standard length 600 mm
Dimensions:
257 x 166 x 77 mm (L x W x H)
Screw connection:
3 x M16
• VdS certication (G210059)
• Patented single tube air sampling system
• Contamination display in %
and signalling at 100 %
• Electronic air ow control
• Externally operable reset button in the
housing
• Remote reset option via terminals
• Long service life, low contamination
• Modbus interface (KRM-2-MOD only)
Accessories
Mounting bracket: KS (for insulated / circular ducts)
KS-WDG (for insulated / circular ducts in
combination with WDG)
Housing: WDG – waterresistant housing for
outdoor installation and increasing
protection class to IP65
Function
The KRM duct smoke detector is designed for smoke detection in
ventilation ducts. It constitutes a combination of a smoke detec-
tor with an adapter system, whose measuring tube and housing
have been specially adapted for optimal air ow through the
smoke detector.
The multi-chamber measuring tube in the air duct transports the
air within the air duct along the entire length of the tube, through
the sensing chamber and back into the air duct. Upon detection
of smoke, the sensor reacts immediately and triggers an alarm.
Over time, the sensor becomes contaminated. Because of alarm
threshold tracking, the sensitivity up to total pollution remains
the same. From 70 % contamination upwards, the sensor is trig-
gered and indicates this by ashing. If the sensor is not replaced
the smoke alarm is triggered at 99 % contamination. The contami-
nation level is indicated in a two-line LED display; at > 70 % it
ashes.
To verify operability, the device is equipped with electronic air
ow monitoring, which lights a blue LED at < 1 m/s. The failure
LED illuminates when the smoke sensor or the electronics are
defective, and in the absence of a smoke detector.
The smoke alarm must be released with the reset button.
A functionality test is also possible with the same button.
The operation functions like a smoke alarm.
Furthermore, the same function takes place on restart or when
the bridge circuit between terminals 9 and 10 is opened (remote
release).
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