System Sensor 6424 User Manual

INSTALLATION AND MAINTENANCE INSTRUCTIONS

6424 Projected Beam Type

3825 Ohio Avenue, St. Charles, Illinois 60174

Smoke Detector

Specifications

General

Range: 30 to 330 Feet (9.1 to 100.6 m)
Sensitivity: 30% ±5% Total Obscuration, or
55% ±5% Total Obscuration
Spacing: 30 to 60 Feet (9.1 to 18.3 m)
Response Time: Alarm: 15 Seconds Max.
Trouble: 15 Seconds Max.
Trouble Condition: 95% or More Obscuration
Improper Initial Alignment
Self-compensation limit reached (service needed)
Test/Reset Features: Obscuration Filters (ALARM/NO ALARM)
Local Alarm Reset Switch
Remote Test and Reset Switch Capability
(compatible with RTS451 Test Station with Magnet)
Indicators: Alarm: Remote Output, Local LED (red)
Trouble: Remote Output, Local LED (yellow)
Normal Operation: Local LED (flashing green)
Alignment Aid: LED Bar Graph (4 red LEDs)
Relays: Alarm; Trouble

Environmental

Temperature: –22°F to 131°F (–30°C to 55°C)
Humidity: 10% to 93% RH Noncondensing
Mechanical
Weight: Receiver: 1.5 lbs (680 g)
Transmitter: 1.3 lbs (590 g)
Mounting: Ceiling or Wall, Separate Mounting Brackets Provided
Wiring: Plug with Attached Cable
Adjustment Angle: Ceiling: ±30° Horizontal/60° Vertical
Wall: ±90° Horizontal/60° Vertical

Electrical (Receiver)

Voltage: 20 to 32 VDC
Maximum Ripple Voltage: 6.0 volts (Peak-to-peak)
Current (24 VDC): Avg. Standby: 10mA Max.
Avg. Alarm: 28.4mA Max.
Avg. Trouble: 27.1mA Max.
Start-up Surge: 19mA Max.
Relay Contacts: .5A at 30 VAC/DC
Reset Time: .6 Seconds Max.
Start-up Time (after 5 min. reset): 1 Minute Maximum
Power Loss: Retain Memory for 5 Minute Minimum

Electrical (Transmitter)

Voltage: 18.8 to 32 VDC
Maximum Ripple Voltage: 5.6 volts (Peak-to-Peak)
Avg. Current (24 VDC): 10mA Max.

1-800-SENSOR2, FAX: [phone]

www.systemsensor.com

D400-18-00 1 I56-494-13R

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Before Installing

Please thoroughly read this manual and applicable sections
of System Sensor’s Projected Beam Detector Application
Guide. Copies of this manual are available from System
Sensor.

General Description

System Sensor Model 6424 is a long range projected beam
smoke detector designed to provide open area protection.
It is to be used with UL-listed, separately supplied power
(4-wire) control panels only. The detector consists of a
separate transmitter and receiver. Smoke entering the area
between the transmitter and receiver causes a reduction in
signal at the receiver. When the obscuration reaches one of
two predetermined thresholds (chosen with a switch in the
receiver), the detector generates an alarm signal. Complete
blockage of the beam causes a trouble signal to avoid false
alarms. Slow changes in obscuration due to a build up of
dirt or dust on the lens of the detector are compensated for
by a microcontroller which continuously monitors the sig
nal strength and periodically updates the alarm and trouble
thresholds. When the self-compensation circuit reaches its
limit, the detector generates a trouble signal, indicating the
need for service.

Three LEDs at the receiver indicate the status of the detec
tor: a red LED for alarm, a yellow LED for trouble, and a
pulsed green LED for standby operation. The alarm signal
latches and can be reset by a momentary power interrup­tion, by using the remote reset input to the receiver if
using the remote test/reset station model RTS451, or with
the local reset button located behind the rear door in the
receiver. A trouble signal automatically resets upon remov­ing the cause of trouble. In addition to these indicators,
there are four LEDs on both the receiver and the transmit­ter which are used as a beam alignment aid. No additional
equipment is needed for alignment of the beam.

Each detector contains one Form A (normally open) con
tact for alarm signals and one Form B (normally closed)
contact for trouble signals. Supervision of power is accom­plished by installing a Power Supervisory End-of-Line Relay
Module (model A77-716) at the end of the detector power
loop. When power is applied to and through the detectors,
the EOL Power Supervisory Module is energized. The relay
contacts, along with the detector’s trouble relay contacts,
can provide a closed series circuit in the control panel’s
alarm-initiating loop. A loss in power or a trouble condition
at the detector causes the respective EOL or trouble relay to
open, resulting in a trouble signal at the control panel.

Parts List

Description Quantity
Receiver Unit 1
Transmitter Unit 1
Receiver Wiring Cable 1
Transmitter Wiring Cable 1
Wall Mounting Bracket 2
Ceiling Mounting Bracket (inside part) 2
Ceiling Mounting Bracket (outside part) 2
Wall Bracket Screw 2
Ceiling Bracket Screw 2
Washers 4
Allen Wrench 1
Instruction Manual 1
Test Filter 1
Cable Exit Plug 1
Hole Plug 1

Detector Placement

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This section of the manual discusses the placement of pro
jected beam detectors. Though this information is based
upon industry expertise, it is intended to be used only as
a technical guide. Always comply with the requirements of
applicable codes and standards such as, NFPA 72, National
Fire Alarm Code, as well as directives of the Authority

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Having Jurisdiction (AHJ). For general information on
the placement of detectors, read System Sensor’s Projected

Beam Detector Application Guide.

Projected beam detectors are usually located with their
beams parallel to the ceiling. However, they can be mount
ed vertically or at any angle to protect the area involved.
Since beam detectors sense the smoke buildup over a dis­tance, they are ideal for locations with high ceilings. They
can also be mounted on a wall or ceiling below the level
of a spot type detector, reducing the effects of air stratifica­tion. Some typical locations would include large areas with
high ceilings such as atriums, warehouses, and factories.

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NOTE: Projected beam smoke detectors should always

be mounted to stable mounting surfaces. See the
MOUNTING LOCATION section for details.

Some fire codes specify spacing on a given center-to-center
distance between detectors under ideal conditions. These
spacings are based on rooms with smooth ceilings and no
physical obstructions between the contents being protected
and the detectors. Moreover, they are also based on a maxi
mum ceiling height, and on the assumption that the value
and the combustible nature of the contents of the room
being protected do not warrant greater protection or closer
spacing.

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In a room with a smooth ceiling, detectors should be spaced

1/2 S

S

12-18 in.

WALL

30 FEET MINIMUM

330 FEET MAXIMUM

TX RX

S

TX RX

1/2 S MAXIMUM

1/4 S
MAX.

S

3 FT. MA

X.

S

1/2 S MAX

.

Tx

Rx

1/2

S

S

S

1/2

S

3 FT.
MAX.

3 FT.
MAX.

MOUNT DETECTOR

ANYWHERE IN THIS AREA

Tx

Rx

between 30 and 60 feet. One-half that spacing between the
beam and the sidewall may be used as a guide. See Figure

1. The beam detector can be mounted with the receiver
on one wall and the transmitter on the opposite wall, or
both suspended from the ceiling, or any wall/ceiling com­bination. In the case of the ceiling mount, the distance
from the end walls should not exceed one-quarter of the
selected spacing (7.5 ft. maximum if the spacing is 30 ft.).
See Figure 2.

Figure 1. Spacing for smooth ceiling (side view):

Figure 3. Sloped ceiling (shed type):

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Figure 4. Sloped ceiling (peaked type):

Figure 2. Spacing for smooth ceiling (top view):

In the case of peaked or sloped ceilings, codes may specify
spacing of detectors by using horizontal spacing from the
peak of the roof or ceiling. Figures 3 and 4 show the spac­ing for both the shed type and peaked type sloped ceilings
On smooth ceilings, beam smoke detectors should gener­ally be mounted between 12 and 18 inches from the ceiling.
In many cases, however, the location and sensitivity of the
detectors shall be the result of an engineering evaluation
that includes the following: structural features, size and
shape of the room and bays, occupancy and uses of the
area, ceiling height, ceiling shape, surface and obstructions,
ventilation, ambient environment, burning characteristics
of the combustible materials present, and the configuration
of the contents in the area to be protected.

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C0536-00

C0539-00

Mounting Locations

Beam detectors require a stable mounting surface for
proper operation. A surface which moves, shifts, vibrates,

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or warps over time will cause false alarm or trouble condi

­tions. Initial selection of a proper mounting surface will
eliminate false alarms and nuisance trouble signals.

Mount the detector on a stable mounting surface, such as
brick, concrete, a sturdy load-bearing wall, support col

­umn, structural beam, or other surface that is not expected
to experience vibration or movement over time. DO NOT
MOUNT the beam detector on corrugated metal walls,
sheet metal walls, external building sheathing, external
siding, suspended ceilings, steel web trusses, rafters, non­structural beam, joists, or other such surfaces.

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Concrete
or Bric

k

Good Mounting
Surface

Poor Mounting

Surface

Sheet
Metal

Poor Mounting
Surface

Good Mounting
Surface

Figure 5. Good and poor mounting surfaces:

C0540-00

Mounting Brackets

Install a ceiling or wall bracket for both the receiver and
transmitter so that when mounted, the receiver and the
transmitter will be at approximately the same height. Each
ceiling bracket is composed of two parts that should be
assembled with inside part between the ceiling and out­side part as shown in Figure 5. The brackets should be
mounted so that the slot in the front of each bracket is
facing the other bracket. Mount the brackets only on solid
structures of the building. To avoid unwanted alarms due
to wall movement, do not mount to flexible walls, such as
sheet metal walls (see MOUNTING LOCATIONS). Mount
brackets with a separation of at least 30 feet but not more
than 330 feet.

Figure 6. Ceiling mount bracket assembly:

Wiring Installation Guidelines

Always install all wiring in compliance with the National
Electrical Code, and/or the applicable local codes, and any
special requirements of the local authority having jurisdic­tion. Proper wire gauges and suitable means for strain relief
should be used. The conductors used to connect beam
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.

Installation wire used for the beam detector shall be no
smaller than 18 gauge (1.0 square mm). For best sys
tem performance, all wiring should be twisted pair and
installed in separate grounded conduit. Do NOT mix fire
system wiring in the same conduit as any other electrical
wiring. Shielded cable may be used to provide additional
protection against electrical interference.

When installing the beam smoke detector in applica
tions where flexible conduit will be used the BMB Beam
Mounting Bracket kit must be installed with the cable
before wiring the unit, as per the instructions supplied
with the kit.

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For wiring, first remove the pre-cut insulation from the con
ductor to be connected, then use a wire nut to connect the
detector wire to the field wire. If the insulation has been
removed from any unused conductors, make sure they are
terminated properly to avoid short circuits. The transmit­ter can be wired in one of two ways. Figure 7 shows the
transmitter permanently connected to the receiver. In this
case the transmitter receives its power along with com­munication for the alignment aid through the connecting
pair of wires. Figure 8 shows an alternative wiring con-

C0741-00

figuration in which the transmitter receives its power from
a remote power source. Temporary wiring can be installed
for the communication needed for transmitter alignment

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