INSTALLATION AND MAINTENANCE INSTRUCTIONS
3825 Ohio Avenue, St. Charles, Illinois 60174
1112/24D Ionization Smoke Detector
1-800-SENSOR2, FAX: 630-377-6495
IMPORTANT: OBSERVE POLARITY
This detector requires that you observe polarity when wiring. If wiring polarity is not observed on the
initiating loop, the unit will send an alarm signal to the control panel to signify incorrect wiring.
Figure 1. Wiring diagram for the 1112/24D detector:
+
POWER
TO
DETECTORS
UL LISTED
CONTROL
PANEL
–
+
+
N.O.
C
–
+
–
+
+
N.O.
C
–
+
–
EOL POWER
SUPERVISION
RELAY (SHOWN
ENERGIZED)
A77-716B 12/24V
EOL RESISTOR
SPECIFIED BY
PANEL
MANUFACTURER
LOOP
+
–
OPTIONAL CLASS A WIRING
NOTE
: Observe polarity in power and initiating loops when wiring.
INITIATING
Before Installing
Please thoroughly read System Sensor Manual I56-407,
Guide for Proper Use of System Smoke Detectors, which
provides detailed information on detector spacing,
placement, zoning, wiring, and special applications.
Copies of this manual are available at no charge from
System Sensor.
NOTICE: This manual should be left with the owner/user
of this equipment.
IMPORTANT: This detector must be tested and maintained
following NFPA 72 requirements. The detector should be
cleaned at least once a year.
General Description
The 1112/24D is a 4-wire ionization smoke detector that
uses a state-of-the-art sensing chamber. This detector is
designed to provide open area protection.
A78-2336-05
Installation of this detector is simplified by the use of an
adapter bracket and a plug-in screw terminal block that
can be prewired to the system, allowing the detector to
be easily installed or removed for cleaning. The detector
sensitivity can be tested in place using the MOD400R
Test Module.
An LED on the detector provides local visual indication of
the detector status. If power is applied to the detector, and
it is functioning normally in standby, the status LED blinks
every five seconds. The LED also latches on in alarm.
The 1112/24D also features visual indication that maintenance is required; if the sensing chamber drifts out of its
sensitivity limits, the LED ceases to blink.
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Specifications
Diameter: 5.5 inches (140 mm)
Height (including adapter bracket): 1.7 inches (43 mm)
Weight: 5.3 oz. (150 g)
Operating Temperature Range: 32° to 120° F (0° to 50°C)
Operating Humidity Range: 10% to 93% Relative Humidity, Noncondensing
Latching Alarm: Reset by momentary power interruption
Relay Contact Rating–
Resistive Load: 0.1A @ 35VDC
Electrical Ratings
System Voltage nominal: 12 or 24 VDC; 8.5 VDC minimum; 35 VDC maximum
Maximum Ripple Voltage: 30% of nominal voltage (peak to peak)
Reset Voltage: 0.8 VDC minimum
Standby Current: 50 µA maximum
Alarm Current: 17 mA typical, 23 mA maximum @ 12V; 19 mA typical, 25 mA maximum @ 24V
Reset Time: 0.3 seconds maximum
Start-up Time: 30 seconds maximum (after 60 second reset)
Figure 2. Surface mounting 1112/24D detector on 31/2
inch and 4 inch octagonal box:
A78-2563-00
Figure 3. 1112/24D detector mounting bracket:
TAMPER RESISTANT TAB
(CUT OFF SMALL TAB TO
ACTIVATE TAMPER-RESIST
FEATURE)
ALIGNMENT ARROWS
A78-2333-02
Mounting
Each 1112/24D detector is supplied with a mounting
bracket that permits the detector to be mounted:
pair may be used to provide additional protection against
electrical interference.
1. To a single gang box, or
2. Directly to a 31/2-inch or 4-inch octagonal box, or
3. To a 4-inch square electrical box by using a plaster ring.
Smoke detectors and alarm system control panels have
specifications for allowable loop resistance. Consult the
control panel specifications for the total loop resistance al-
Wiring Installation Guidelines
lowed for the control panel being used before wiring the
detector loops.
CAUTION
Be certain to observe polarity when wiring.
All wiring must be installed in compliance with the National Electrical Code, applicable local codes, and any special requirements of the local authority having jurisdiction.
Proper wire gauges should be used. The conductors used to
connect smoke detectors to control panels and accessory
devices should be color-coded to reduce the likelihood of
wiring errors. Improper connections can prevent a system
from responding properly in the event of a fire.
The screw terminal block accepts 14 – 22 gauge wire. For
best system performance, all wiring should be installed in
separate grounded conduit. Do not mix fire system wiring
in the same conduit as any other electrical wiring. Twisted
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Wire connections are made by stripping about 1/4 inch of
insulation from the end of the feed wire, inserting the wire
into the appropriate terminal, and tightening the screw to
secure the wire in place.
Tamper-Resist Feature
This detector includes a tamper-resist feature that prevents
its removal from the bracket without the use of a tool. To
make the detector tamper-resistant, remove the smaller tab
by breaking it at the scribed line on the tamper resistant tab
on the detector mounting bracket (see Figure 3), then install the detector. To remove the detector from the bracket
once it has been made tamper resistant, use a small screwdriver to depress the tamper-resistant tab, located in the
slot on the mounting bracket (see Figure 4), and rotate the
I
N
T
A
P
T
O
N
O
D
detector counterclockwise.
Installation
WARNING
Remove power from the control unit or initiating device circuits before installing detectors.
1. Wire the plug-in screw terminal block per Figure 3 and
plug the terminal block into the detector.
2. Align the arrows on the detector with the arrows on the
mounting bracket.
3. Rotate the detector clockwise in the mounting bracket
until it clicks into place.
4. After all detectors have been installed, apply power to
the control unit or initiating device circuits.
NOTE: This detector has a feature that will signal an
alarm at the control panel if wiring polarity is
incorrect.
5. Test the detector as described in TESTING.
6. Reset the detector at the system control panel.
7. Notify the proper authorities the system is in operation.
CAUTION
Dust covers are an effective way to limit the entry of dust
into smoke detector sensing chambers. However, they may
not completely prevent airborne dust particles from entering the detector. Therefore, System Sensor recommends the
removal of detectors before beginning construction or other
dust producing activity. Be sure to remove dust covers from
any sensors that were left in place during construction as
part of returning the system to service.
Testing
NOTE: Before testing, notify the proper authorities that
the smoke detector system is undergoing maintenance and, therefore, will be temporarily out of
service. Disable the zone or system undergoing
maintenance to prevent unwanted alarms.
Detectors must be tested after installation and following periodic maintenance. Test the 1112/24D as follows:
A. Test Switch
1. A recessed test switch is located on the detector housing (See Figure 4).
2. Press and hold the recessed test switch with a 0.18
inch maximum diameter tool such as an allen wrench
or small screwdriver.
3. The detector’s LED should light within 5 seconds.
B. Test Module (System Sensor Model No. MOD400R).
The MOD400R test module can be used with a DMM or
analog voltmeter to check the detector sensitivity as described in the test module’s manual.
C. Smoke Entry Test
Hold a smoldering punk stick or cotton wick at the side
of the detector and gently blow smoke through the detector until the unit alarms.
A detector that fails to activate with any of the above tests
should first be cleaned as outlined in MAINTENANCE. If
the detector still fails to activate, return it for repair.
Notify the proper authorities the system is back in operation.
Figure 4. Top and side views showing location of test switch:
LED
TEST MODULE
SOCKET
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RECESSED TEST
SWITCH
A78-2564-01A
PUSH RECESSED
SWITCH WITH A
0.18″ MAX. DIAMETER TOOL
A78-2564-00C
Maintenance
NOTE: Before removing the detector, notify the proper au-
thorities that the smoke detector system is undergoing maintenance and will be temporarily out of
service. Disable the zone or system undergoing
maintenance to prevent unwanted alarms.
1. Remove the detector housing by gently prying the four
housing tabs on the bottom of the base with a smallbladed screwdriver and pull the housing from the base.
2. Vacuum the screen carefully without removing it.
3. Remove the screen by pulling it straight away from the
sensing chamber (see Figure 5).
4. Clean the sensing chamber by vacuuming or blowing
out dust and particles.
5. Replace the screen by placing it over the sensing chamber. Rotate the screen until is snaps into place.
6. Replace the housing by aligning the three triangular slots
on the base with their counterparts on the housing. Gently press the housing until it locks in place.
7. Reinstall the detector.
8. Notify the proper authorities that the system is back in
operation.
Figure 5. Removal of cover and screen for cleaning:
REMOVABLE
HOUSING
REMOVABLE
SCREEN
SENSING
CHAMBER
BASE
A78-2565-03
The Limitations of Property Protection Smoke Detectors
This smoke detector is designed to activate and initiate emergency action, but will do so only when it is used in conjunction with an authorized
fire alarm system. This detector must be installed in accordance with
NFPA standard 72.
Smoke detectors will not work without power. AC or DC powered
smoke detectors will not work if the power supply is cut off.
Smoke detectors will not sense fires which start where smoke does not
reach the detectors. Smoldering fires typically do not generate a lot of
heat which is needed to drive the smoke up to the ceiling where the
smoke detector is usually located. For this reason, there may be large delays in detecting a smoldering fire with either an ionization type detector
or a photoelectric type detector. Either one of them may alarm only after
flaming has initiated which will generate the heat needed to drive the
smoke to the ceiling.
Smoke from fires in chimneys, in walls, on roofs or on the other side of a
closed door(s) may not reach the smoke detector and alarm it. A detector
cannot detect a fire developing on another level of a building quickly or at
all. For these reasons, detectors shall be located on every level and in
every bedroom within a building.
Smoke detectors have sensing limitations, too. Ionization detectors and
photoelectric detectors are required to pass fire tests of the flaming and
smoldering type. This is to ensure that both can detect a wide range of
types of fires. Ionization detectors offer a broad range of fire sensing capa-
Three-Year Limited Warranty
System Sensor warrants its enclosed smoke detector to be free from defects in materials and workmanship under normal use and service for a
period of three years from date of manufacture. System Sensor makes no
other express warranty for this smoke detector. No agent, representative,
dealer, or employee of the Company has the authority to increase or alter
the obligations or limitations of this Warranty. The Company’s obligation
of this Warranty shall be limited to the repair or replacement of any part of
the smoke detector which is found to be defective in materials or workmanship under normal use and service during the three year period commencing with the date of manufacture. After phoning System Sensor’s toll
free number 800-SENSOR2 (736-7672) for a Return Authorization number,
send defective units postage prepaid to: System Sensor, Repair Depart-
WARNING
bility but they are somewhat better at detecting fast flaming fires than
slow smoldering fires. Photoelectric detectors sense smoldering fires better
than flaming fires which have little, if any, visible smoke. Because fires develop in different ways and are often unpredictable in their growth, neither type of detector is always best, and a given detector may not always
provide early warning of a specific type of fire.
In general, detectors cannot be expected to provide warnings for fires resulting from inadequate fire protection practices, violent explosions, escaping gases which ignite, improper storage of flammable liquids like
cleaning solvents which ignite, other similar safety hazards, arson, smoking in bed, children playing with matches or lighters, etc. Smoke detectors
used in high air velocity conditions may have a delay in alarm due to dilution of smoke densities created by frequent and rapid air exchanges. Additionally, high air velocity environments may create increased dust
contamination, demanding more frequent maintenance.
To keep your equipment in excellent working order, ongoing maintenance
is required per the manufacturer’s recommendations and UL and NFPA
standards. At a minimum, the requirements of Chapter 7 of NFPA 72, the
National Fire Alarm Code, shall be followed. A preventative maintenance
agreement should be arranged through the local manufacturer’s representative. Though smoke detectors are designed for long life, they may fail at
any time. Any smoke detector, fire alarm equipment, or any component of
that system which fails shall be repaired or replaced as soon as possible.
ment, RA #__________, 3825 Ohio Avenue, St. Charles, IL 60174. Please
include a note describing the malfunction and suspected cause of failure.
The Company shall not be obligated to repair or replace units which are
found to be defective because of damage, unreasonable use, modifications, or alterations occurring after the date of manufacture. In no case
shall the Company be liable for any consequential or incidental damages
for breach of this or any other Warranty, expressed or implied whatsoever,
even if the loss or damage is caused by the Company’s negligence or fault.
Some states do not allow the exclusion or limitation of incidental or consequential damages, so the above limitation or exclusion may not apply to
you. This Warranty gives you specific legal rights, and you may also have
other rights which vary from state to state.
D200-63-00 4 I56-931-06
© System Sensor 1998
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