Bosch DS240, DS241 User Manual

Installation Instructions

DS240 and DS241

Long Range Beam Smoke Detectors

1.0 Description

The DS240 and DS241 are long range projected beam type smoke detectors which consist of a separate transmitter and receiver. Internal pointability provides coverage flexibility without the need for brackets. Automatic Signal Synchronization and Range Adjustment reduce installation costs. Selectable sensitivity and alarm response time provide installation flexibility.

2.0 Specifications

• Operating Volt age: DS240: 18.0 VDC to 32.0 VDC DS241: 10.2 VDC to 15.0 VDC

• Standby Current: DS240: Receiver: 45 mA @ 24.0 VDC

Transmitter: 20 mA @ 24.0 VDC

DS241: Receiver: 50 mA @ 12.0 VDC

Transmitter: 20 mA @ 12.0 VDC

• Receiver Alarm

Current: DS240: 60 mA @ 24.0 VDC

DS241: 75 mA @ 12.0 VDC

• Range (distance

between transmitter and receiver): 30 ft to 350 ft (9 m to 107 m)

• Spacing (distance

between systems): Allow no more than 60 ft (18 m) between

systems. Sixty foot spacing is confirmed by Underwriters Laboratories, Inc. testing.

• Pointability: Internally pointable optics for ±90° horizontal, and ±10° vertical adjustment.

• Sensitivity: Field selectable for 20, 30, 40, 50, 60, or 70 percent beam obscuration.

• Alarm Contacts: Normally Open contacts rated 1 A, 60 VDC maximum for DC resistive loads. Do not use with capacitive or inductive loads.

• Trouble Contact s: Normally Closed contacts rated 1 A, 60 VDC maximum for DC resistive loads. Do not use with capacitive or inductive loads.

• Aux. Alarm

Contacts: Form "C" (NO, C, NC) contacts rated 1 A,

60 VDC maximum for DC resistive loads. Do not use with capacitive or inductive loads.

• Tamper: Receiver: Access door tamper switch in

series with trouble contacts.

Transmitter: Upon cover’s removal, cover

tamper switch interrupts transmission.

• System Signaling: Conventional 4-wire system. Not for use with systems that incorporate an alarm verification feature.

• Signal Delay: Fire : Selectable 30 sec or 5 sec Trouble: 20 ± 2 sec

• Temperature: The storage and operating temperature range is -22°F to +130°F (-30°C to +54°C).

For UL Listed installations, the range is +32°F to +130°F (0°C to +54°C).

• Mounting: The units are designed to be mounted to 4 in. (10 cm) square or octagonal electrical boxes (not supplied).

• Listings and Approvals: UL S3019

ULC CS692 MSFM Permit #1943 NY City MEA Acceptance #MEA274-93-E CSFM #7260-1062:106 F M Job #OX2A9.AY

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• Standard Accessories: DIS2000 Remote Test/Indicator Plate and

Test Cable

• Options: DIS240 Remote Indicator Plate, TK240

Field Test Kit, AL240 Alignment Light, and TC2000 Test Cord.

3.0 Principle of Operation

Each DS240 or DS241 beam smoke detector has a separate transmitter and receiver. The transmitter transmits an invisible infrared beam of a specific frequency and intensity. The receiver detects, then measures the beam’s intensity (see

Figure 1 - Infrared Transmission

As the beam is obscured by smoke, the receiver senses a decrease in the signal strength and measures that decrease. The receiver compares the signal level with two preset thresholds: an alarm threshold which is set using the sensitivity switch and a trouble threshold which is preset at approximately 10%. If the signal falls below the alarm threshold for the programmed alarm period, the receiver signals an alarm (see

Figure 2 - Beam Obscuration

If the signal falls below the trouble threshold for more than 20 sec, such as might happen if the beam is blocked by a foreign object, the receiver signals a trouble condition (see

Figure 3 - Beam Blockage

The receiver automatically compensates for the gradual loss of signal due to dust/dirt build-up on the cover. After 50 percent of the signal is lost, the receiver will indicate a trouble. When the dust/dirt build-up is cleaned or the blockage is removed, the detector automatically goes back to its normal operation level.

A trouble will be indicated at the receiver if the beam strength is increased by more than 20% for greater than 20 sec. Causes include improper initial alignment or the removal of a partial beam blockage at the time of alignment. Preform a fine-tune alignment (see

7.3 Fine Tune Alignment

on page 6).

Figure 1

Figure 2

Figure 3

Section

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4.0 Installation Considerations

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4.2 Avoid sources of bright light

The proper location and spacing of detectors is critical in a properly installed and operating fire alarm system. For best results, it is recommended that the detectors be located and spaced in accordance with the National Fire Protection Association (NFPA) Standard 72 "The National Fire Code.” This standard is available at a nominal cost from The National Fire Protection Association, Batterymarch Park, Quincy, MA, 02269.

In all installations, good engineering judgement should prevail. The following are some general considerations:

• Do not use mirrors. The detectors should be installed with a clear line-of-sight between the transmitter and receiver.

• The beam path should be clear of moving objects.

• Set the sensitivity based on the distance between the transmitter and receiver. See

Section 7.2 Sensitivity Adjustment

on page 5.

• The detectors may be mounted directly to the ceiling or to side walls. Do not mount the units where the beam path may run parallel within 4 in. (10.2 cm) of a corner.

• For a sloped or peaked ceiling, the beam path should be located within 3 ft (1 m) of the ceiling’s peak.

• Stratification of air may hinder smoke from reaching detectors mounted close to the ceiling. Stratification occurs when smoke, rising because it is warmer than the surrounding air, reaches a level where it is the same temperature as the surrounding air and will not rise to the ceiling. If stratification is considered a possibility, extra beams should be installed where stratification is expected.

Sunlight and light from extremely bright sources such as the exposed bulbs of high pressure sodium, mercury vapor, and metal halide lights can cause stray signals. The receiver should not be pointed toward any of these sources.

Sunlight: Avoid pointing the receiver directly at the rising or setting sun. If you are installing the unit where sunlight can’t be avoided, mount the receiver slightly higher than the transmitter and aimed down toward the transmitter. This should reduce this problem by causing the receiver to look below the horizon.

Bright Lights: Don’t mount the receiver where it is looking at exposed bulbs of high pressure sodium, mercury vapor, and metal halide lights. The illustration below shows where these exposed lights should be avoided.

Keep bright lights out of this area

Receiver

4.5 ft. (1.4 m)

225 ft. (68.6 m)

350 ft. (106.8 m)

14.5 ft. (4.4 m)

Bare fluorescent lights may also pose a problem especially in long hallways where a series of lights run perpendicular to the beam. Incandescent lights are not a problem as long as they are not directly in the beam path.

4.3 Use the correct wire gauge and length

Beam smoke detectors are often used to protect very large areas. This means that the wire runs used to power the detectors and signal alarm conditions can be very long. The voltage available at the end of very long wire runs may not be sufficient to power the detector, especially when the system is running on battery backup. It is very important that the correct wire gauge is used for these installations.

• Avoid areas subject to normal smoke concentrations such as kitchens and garages.

• Do not install units where normal ambient temperatures are below -22°F (-30°C) or above +130°F (+54°C).

The following are some specific installation considerations:

4.1 Avoid Sources of Heat and Air Movement

The detectors should be located where the beam path will not pass near heating and cooling outlets.

• Don’t mount where hot or cold air can blow directly into the beam path.

• Heating, ventilating, and air conditioning systems can cause smoke to be blown away from the beam path.

- Smoke must accumulate in the beam path to be detected.

• Heaters mounted close to the beam path can cause the beam to become distorted.

You can test for beam distortion by monitoring the signal voltage. After setup, the signal voltage of the detector should read 4 VDC. Monitor the voltage and turn on all heating and cooling devices in the area. The signal voltage should not fluctuate more than 0.20 VDC. If it does, the detector should be moved to avoid these disturbances.

Use the following chart to determine the proper wire size, wire length and the number of transmitter and receiver pairs that can be used.

4.4 Provide a stable mounting surface

4.6 Consider the expected Fire load

Beam smoke detectors depend on the measurement of the projected beam to sense smoke. Therefore, shifts in the alignment of the beam due to movement of the transmitter/receiver can cause trouble or alarm conditions.

• Always select a stable mounting surface.

• Never mount the unit to a suspended support such as a pipe or length of wood supported at only one end.

This type of mounting can create a “pendulum effect” which greatly multiplies even very small movements at one end of the support. For example, a 2 in. (5.1 cm) movement translates into a beam misalignment of over 20 ft at 350 ft (6 m at 107 m).

Mounting surfaces should be supported at opposite corners to reduce the pendulum effect.

• Always select surfaces not subject to building movement.

The automatic compensation circuits of the DS240 and DS241 will eliminate most problems created by normal building expansions and contractions. In some unusual circumstances, the walls and

support structure may be subject to more significant movement due to the operation of heavy equipment, such as cranes, anchored to the top of the walls.

When designing a fire alarm system, consider the expected fire load within the application.

For instance, fires caused by the ignition of flammable petroleumbased liquids usually result in a rapid buildup of heavy smoke. When these types of fires are probable, use sensitivity settings 0 or 1 which provide a response time of 5 sec.

5.0 Mounting

NOTE: This product is not designed for use in outdoor applications.

Install a 4 in. (10 cm) square or octagonal electrical box (not supplied) to a rigid surface that will not be subject to movement or vibrations.

NOTE: If not mounting to an electrical box, be sure the surface will

not be subject to movement or vibrations. For example: do not mount directly to a suspended ceiling without extra support.

• Remove the receiver's access door (1 screw), then remove the cover (4 screws). See

Figure 4

COVER MOUNTING

SCREWS (4)

When in doubt about mounting surface stability, measure the signal voltage of the detector. This voltage should be 4.0 VDC. Misalignment of the beam can cause this voltage to increase or decrease. The detector will indicate a trouble condition when the voltage increases to more than 4.8 VDC, or when it decreases to less than 2.0 VDC over a long period of time or to 0.4 VDC greater than 20 sec. For more information on reading this voltage, see

Voltage Calibration

on page 6).

Section 8.3 Reference

If movement of the mounting surface is suspected, relocate the detector to a surface that does not move or add supports to the mounting surface to prohibit movement.

• DO NOT over-tighten the mounting screws. When the detector is mounted to an electrical mounting box

[4 in. (10 cm) square or octagonal], the mounting plate may bow as a result of the mounting box screw tabs being below flush with the top edges of the mounting box. Over-tightening the mounting screws bows the mounting plate inward at the bottom, causing the optics to aim low.

Irregularities in the flatness of the mounting box edge surfaces or screw tabs will worsen this condition. Using only mounting boxes with flat, regular surfaces and properly formed screw tabs, and tightening the mounting screws to secure the mounting plate to 2 in./lb torque will minimize any misalignment caused by bowing of the mounting plate.

4.5 Consider the effects of stratification in cold environments

In very cold environments such as unheated warehouses, smoke may cool very quickly and is less likely to rise to the ceiling. Consider additional units at lower mounting heights to help compensate for this situation.

ACCESS DOOR

Figure 4 - Access Door and Cover

• Remove the receiver’s backplate by removing the single mounting screw from the top of the circuit board carrier plate then separating the two plates (see

EXPOSE BACKPLATE

REMOVE TO

DO NOT

REMOVE

Figure 5

MOUNTING

SLOTS (4)

WIRING

ENTRANCE

Figure 5 - Removing the Backplate

• Bring wiring from the electrical box through the wire entrance.

NOTE: All wiring should be unpowered.

• Securely mount the backplate to the electrical box.

• Return the circuit carrier plate to the backplate. Secure it in place with the single mounting screw.

• Repeat this mounting procedure for the transmitter.

6.0 WIRING

Only apply power after all connections have been made and inspected.

CAUTION

• Wire the transmitter and receiver terminals as follows (see

Figure 6

NOTE: Do not install on verified fire circuits.

NOTE: Do not coil excess wiring inside the units.

• Transmitter Terminals 1 & 2: Input power terminals. See for the operating voltages of the DS240 and DS241.

Control Panel

Power Loop – Power Loop +

Receiver

Alarm Loop

Fire Alarm

AUX. RELAY ALARM

1234567

FIRE

ALARM

End of Line

–

Transmitter

Figure 6 - Wiring a Single Unit

Section 2.0 Specifications

TRBL

ALARM

resistor

VDC

–+

on page 1

• Slide the Remote Indicator Connector over the pins just to the right of the receiver’s terminal strip.

DS240/DS241 Receiver

Fire

Trouble

10 to 32

Alarm

VDC

–+

Violet Black Red Yellow Green

Remote Indicator

Plate Connector

Fire Alarm

Control Panel

Alarm Loop

Power Loop – Power Loop +

7654

EOL

DIS2000

Voltage Monitor

Ground (–)

Red LED

Yellow LED

Green LED

• Receiver Terminals 1, 2 & 3:

Figure 7 - Connecting the DIS2000 Remote Indicator Plate

Form "C" Auxiliary relay contacts. Terminals 1 & 2 will open on fire alarm; Terminals 2 & 3 will close (short) on fire alarm.

NOTE: If connecting a DIS240 Remote Test/Indicator Plate,

consult the

DIS240 Installation Instructions

(P/N: 24171).

• Receiver Terminals 4 & 5: Normally Open Fire alarm contacts will close (short) on fire

7.0 SET-UP

alarm.

Before starting this section, confirm that all connections have been

• Receiver Terminals 6 & 7:

made and are secure, then apply power to both units.

Normally Closed Trouble contacts will open for trouble alarm.

• Press the Aim Mode button (directly above the green LED) on the

• Receiver Terminals 8 & 9: Input power terminals. See

Section 2.0 Specifications

on page 1

transmitter (see

Figure 8

up while its cover is off.

). This allows the transmitter to power

for the operating voltages of the DS240 and DS241.

NOTE: Resetting from a fire alarm requires power to the receiver to

AIM MODE

BUTTON

be interrupted for at least one second. If not provided by the fire panel, it can be accomplished by installing a switch in series with Terminal 9.

Remote Indicator Plate

The DIS2000 Remote Indicator Plate is shipped with the DS240/ DS241 as a standard accessory. Although the Remote Indicator Plate is not required, the manufacturer recommends its installation to provide a means of checking the condition of the detector from ground

GREEN

LED

level. If a DIS2000 or DIS240 Remote Indicator Plate will be used, install

the Remote Indicator Connector to the receiver now (see Figure 7).

Figure 8 - Cutout View of Transmitter Circuit Board Showing

Aim Mode Button Location

- Check the transmitter’s green LED. It should be flashing on

NOTE: The DIS240 remote indicator should be located no further

and off. than 100 ft (31 m) from the receiver and wired with 18 AWG (1.2 mm) or larger wire. The DIS2000 may be wired up to 500 ft (152 m) from the receiver.

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