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Duct Smoke
Detector for Special
Applications
Model
2451 with B404B/B404BT
and RTC Remote Test Kit
UL 268A
(Requires RTC
accessory)
Product Overview
Low standby current
Two LEDs “blink” in standby
Detector head plugs easily into base
Field adjustable sensitivity
Built-in test switch
Field sensitivity metering of detector to meet
the requirements of NFPA 72
120VAC and 24VAC/DC bases with built-in
shorting spring
Built-in tamper-resistant feature
Designed for mounting on standard electrical box
SEMS screws for easy wiring and positive wire
retention
Removable cover and insect screen for field
cleaning
Specifications
Operating Voltage/ Alarm current
Mounting base dependent (see char t)
Standby current
120 mA maximum
Sensitivity
3% ± .7% / ft.
Weight
0.5 ib. (277 g)
Size
3.2˝/8.1 cm height
6.2˝/15.8 cm diameter
Construction
Flame retardant Nor yl plastic
Operating Temperature
32° to 120°F (0° to 49°C)
Humidity Range
10 to 93% RH non-condensing
Air Velocity Rating
0 to 3000 fpm maximum
2451 with B404BT and RTC
(Includes the RTS451)
The System Sensor 2451
photoelectronic smoke detector is UL listed
to UL 268A specifically for use in no-flow/low-flow air-handling sys-
tems. It’s designed for installations where a standard Venturi principle
duct smoke detector is unsuitable. This is the perfect combination for
installation in ducts where the air velocity is below 500 fpm or for duct
sizes as small as 8 inches in diameter. Pendant mounted in a standard
electrical box within the duct, the twist-in/twist-out head allows easy
removal from the base for quick cleaning and maintenance. The detec-
tor can be combined with the System Sensor B404B 120VAC base or
the B404BT 24VAC/DC base. Remote testing is accomplished using our
Remote Test Coil accessory that includes the RTS451. The APA451,
Remote Annunciator with Piezo Alarm, can also be connected to pro-
vide an audible and visible indication of smoke detector status.
Architectural/Engineering Specifications
The air duct detector shall be a System Sensor model 2451 Series Smoke detector UL listed to UL 268A specifically for use in
air handling systems when used in conjunction with the B404B (120VAC) or the B404BT (24VAC/DC) base. The detector shall
operate at air velocities up to 3000 feet per minute. It shall be capable of local testing via magnetic switch or remote testing
using the UL listed RTC Remote Test Coil accessory with the RTS451 Remote Test Station. It shall be capable of providing
duct smoke detector status via the UL listed model APA451 Piezo Annunciator.
Base Chart
Base
Model
B404B
B404BT
Version
UL/ULC
UL
Loop Type
4-wire
4-wire
Current Limit
resistor
Yes
Yes
Alarm Contact Type
Form A&C + A supy.
Form A&C + A supy.
Nominal Voltage
120VAC
24VAC/DC rms
Alarm Current
(mA)
20.4
94
Junction Box Selection
Base Model
B404B
B404BT
Single Gang
No
No
3
1
/
2
˝ Oct.
No
No
4˝ Oct.
Yes
Yes
4˝ Sq.
Yes
Yes
50mm 60mm
No
No
No
No
75mm
No
No
Wiring Guide
B404B Typical Wiring Diagrams:
(+)
(–)
RA400Z
(Optional)
(+)
(–)
RA400Z
(Optional)
3
4
3
4
RELEASING
DEVICE
BLACK LEADS
TRANSFORMER
PRIMARY
2
1
5
11
14
13
12
6
7
8
9
10
2
1
5
11
14
13
12
6
7
8
9
10
EOL
SPECIFIED
BY PANEL
MANUFACTURER
120 VAC
120 VAC
FIRE
ALARM
CONTROL
PANEL
ALARM INITIATION LOOP
RELEASING
DEVICE
POWER
POWER
RELEASING
DEVICE
H0270-00
B404B Base Terminals
No.
1
2
3
4
5
6
7
8
9
10
11
12
13
14
Function
Remote Annunciator (+)
Not Used
Not Used
Remote Annunciator (-)
Not Used
N.O.
N.O.
N.O.
N.O.
C.
C.
N.O.
N.C.
C.
Alarm Relay
Form C
Auxiliary Contacts
Alarm Relay
Form A
Initiation Contacts
FIRE
ALARM
CONTROL
PANEL
6
120 VAC
7
8
9
10
11
3
BLACK LEADS
TRANSFORMER
PRIMARY
4
RA400Z
(Optional)
Supervisory Relay
Form A Contacts
2
1
5
14
13
12
EOL
SPECIFIED
BY PANEL
MANUFACTURER
ALARM INITIATION LOOP
POWER
FAN/DAMPER
CONTROL
H0271-00
B404BT Typical Wiring Diagrams:
3 APA451
2
1 (Optional)
3 APA451
2
1 (Optional)
3
4
RELEASING
DEVICE
3
4
RELEASING
DEVICE
2
1
24 VACrms/DC
2
5
11
14
13
12
24 VACrms/DC
EOL
1
6
5
11
14
13
12
SPECIFIED
BY PANEL
MANUFACTURER
6
7
8
9
10
7
8
9
10
FIRE
ALARM
CONTROL
PANEL
ALARM INITIATION LOOP
H0268-00
NOTE: ABOVE DIAGRAM SHOWS NFPA REQUIRED WIRING OF SUPERVISED
SYSTEMS. SCHEMATIC SHOWN BELOW FOR REFERENCE.
3 APA451
2 (Optional)
1
SUPERVISORY
RELAY
B404BT Base Terminals
No.
1
2
Function
Remote Annunciator (+)
Test Coil (+)
Not Used
EOL
Remote Annunciator (-)
CT POWER SOURCE
ROPRIATE TERMINALS
H DETECTOR. SEE
CATIONS FOR
NAL POWER SUPPLY
ATION.
CONTROL
PANEL
SUPERVISORY
RELAY
3
4
ALARM
RELAY
ALARM
RELAY
5
6
7
RTC (-)
N.O.
N.O.
N.O.
N.O.
C.
C.
N.O.
N.C.
C.
3
4
SPECIFIED
BY PANEL
MANUFACTURER
Supervisory Relay
Form A Contacts
2
14
1
24 VACrms/DC
8
9
10
11
12
13
14
FAN / DAMPER
SHUTDOWN
5
11
13
12
RING OF AUXILIARY
S, REFER TO
ACTURER'S
ATION INSTRUCTIONS
TACT MANUFACTURER.
6
Alarm Relay
Form A
Initiation Contacts
7
8
9
10
Alarm Relay
Form C
Auxiliary Contacts
HE SUPERVISORY RELAY NOW
ES A "FORM C" CONTACT FOR
MIZED APPLICATIONS.
ANDARD APPLICATIONS, ONLY
" CONTACT IS USED
POWER
RTC Ring Replacement of B404BT:
H0269-00
RTC Wiring Diagram:
B404B/B404BT
REMOTE
ANNUNCIATOR (+)
TEST COIL (+)
RTS451
1
2
3
4
FIELD
INSTALLED
JUMPER
1
2
3
4
5
TEST
COIL
ALARM
TEST
COIL
EOL RESISTOR
SPECIFIED BY
PANEL MANUFACTURER
H0272-00
RTC (–)
5
4-POSITION
TERMINAL
BLOCK
H0233-00
ALARM
ALARM
POWER
RESET
RTS451KEY
Remote Test Station
(provided with Remote
Test Coil)
APA451
Piezo Annunciator
RA400Z
Remote Annunciator
Top Mount in Ventilation Shaft
Ordering Information
Part No.
2451
B404B
B404BT
Description
Photoelectronic plug-in detector (order one of the bases
listed below and the RTC)
120VAC detector base
24VAC/DC detector base
APA451
RA400Z
Accessories
RTC
Description
Remote test coil kit (Includes RTS451 remote
test station)
Remote annunciator with piezo alarm
Remote annunciator
System Sensor Sales and Service
System Sensor Headquarters
3825 Ohio Avenue
St. Charles, IL 60174
Ph: 800/SENSOR2
Fx: 630/377-6495
Documents-on-Demand
800/736-7672 x3
www.systemsensor.com
System Sensor Canada
Ph: 905.812.0767
Fx: 905.812.0771
System Sensor Europe
Ph: 44.1403.891920
Fx: 44.1403.891921
System Sensor in China
Ph: 86.29.524.6253
Fx: 86.29.524.6259
System Sensor in Singapore
Ph: 65.273.2230
Fx: 65.273.2610
System Sensor – Far East
Ph: 85.22.191.9003
Fx: 85.22.736.6580
System Sensor – Australia
Ph: 613.54.281.142
Fx: 613.54.281.172
System Sensor – India
Ph: 91.124.2371770 x.2700
Fx: 91.124.237.3118
© 2004 System Sensor. The company reserves the right to change product specifications without notice.
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