SYSTEM SENSOR DH400ACDC (01) PDF DOCUMENT

Please thoroughly read the System Sensor Guide for Proper Use of Smoke Detectors in Duct Applications (I56-473), which provides detailed information on detector spacing, placement, zoning, wiring, and special applications. NFPA Standards 72 and 90A should also be referenced for detailed information.

This manual should be left with the owner/user of this equipment.

This detector must be tested and maintained regularly following NFPA 72 requirements. The detector should be cleaned at least once a year.

An HVAC system supplies conditioned air to virtually every area of a building. Smoke introduced into this air duct system will be distributed to the entire building. Smoke detectors designed for use in air duct systems are used to sense the presence of smoke in the duct.

Model DH400ACDC Air Duct Smoke Detectors are supplied with model 1451DH ionization detector heads or model 2451 photoelectronic detector heads. These two smoke detection methods are combined with an efficient housing design that samples air passing through a duct and allows detection of a developing hazardous condition. When sufficient smoke is sensed, an alarm signal is initiated at the fire control panel monitoring the detector, and appropriate action can be taken to shut off fans and blowers, change over air handling systems, etc. These actions can facilitate the management of toxic smoke and fire gases throughout the areas served by the duct system.

DH400ACDC detectors are designed to operate from 24 VDC, 24 VAC, 120 VAC, or 240 VAC. Alarm and supervisory relay contacts are available for control panel interface (alarm initiation), HVAC control, and other auxiliary functions. These detectors are not designed for 2-wire application.

For testing, the alarm can be enabled by a magnet activated test switch, by insertion of a calibrated test card into the sensing chamber (photoelectronic version only), or by the optional remote test station. The duct smoke detectors latch into alarm state when alarm occurs. LEDs on each detector illuminate to provide local alarm indication, and optional accessories offer a variety of annunciation capabilities.

The detector can be reset by a momentary power interruption, by the magnet activated reset switch, or by the optional remote test station.

1. Complete housing base and cover assembly

2. Two #10 sheet metal mounting screws

3. Two sampling tube filters

4. One test magnet

5. Drilling template

6. Two 5/16 O-rings

7. Two rubber tube bushing seals

8. Four #6 self-tapping mounting screws for the sampling and optional exhaust tube extension

9. One filter adapter

10. One inlet tube end plug

11. Two #10 speed nuts

NOTE: The inlet sampling tube must be ordered separately. It must be the correct length for the width of the duct where it will be installed.

WARNING: The National Fire Protection Association has established that DUCT DETECTORS MUST NOT BE USED AS A SUBSTITUTE FOR OPEN AREA DETECTOR PROTECTION as a means of providing life safety. Nor are they a substitute for early warning in a building’s regular fire detection system.

System Sensor supports this position and strongly recommends that the user read NFPA Standards 90A, 72, and 101. The DH400ACDC Air Duct Smoke Detectors are listed per UL 268A.

WARNING: This device will not operate without electrical power. Frequently, fire situations may cause an interruption of power. The system safeguards should be discussed with your local fire protection specialist.

WARNING: This device does not sense smoke unless the ventilation system is operating.

CAUTION: For this detector to function properly, it MUST be installed according to the instructions in this manual. Furthermore, the detector MUST be protected from the elements and operated within ALL electrical and environmental specifications listed in this manual. Failure to comply with these requirements may prevent the detector from activating when smoke is present in the air duct.

[5.1] Verify duct air flow direction and velocity

[5.2] Drill the mounting holes

[5.3] Secure the detector housing to the duct

[5.4] Install the sampling tube

[5.5] Complete the field wiring

[5.6] Install the filters and check pressure differential

[5.7] Perform detector check

[5.8] Install the cover

Model DH400ACDC detectors are designed to be used in air handling systems having air velocities of 500 to 4000 feet per minute. Be sure to check engineering specifications to ensure that the air velocity in the duct falls within these parameters. If necessary, use a velocity meter to check the air velocity in the duct.

Remove the paper backing from the mounting template supplied. Affix the template to the duct at the desired mounting location. Make sure the template lies flat and smooth on the duct. Center punch holes A and B. Drill the holes as indicated on the template. Slide the two speed nuts over the two small holes (hole A) next to the sampling tube bushing holes (hole B) previously drilled in the duct.

Remove the duct housing cover. Slide the foam gaskets over the tube bushings. Make sure the two small holes in the gaskets line up with the two base mounting holes. Put one 5/16-inch O-ring over each of the two #10 sheet metal screws. Use the two sheet metal screws to screw the detector housing to the duct. CAUTION: Do not overtighten the screws.

The inlet tube is identified by a series of air inlet holes on the tube. This tube must be purchased separately. Order the correct length, as specified in Table 1, for the width of the duct where it will be installed. The exhaust tube is molded into the base of the duct housing, and the A2440-00 Exhaust Tube Extension is available as an accessory in those cases where the molded exhaust port does not extend at least 2 inches into the duct.

The inlet tube is always installed in the centermost housing bushing, with air inlet holes facing into the air flow. To assist proper installation, the tube’s mounting flange is marked with arrows. Make sure the inlet tube is mounted so that the arrows point into the air flow.

Mounting the detector housing in a vertical orientation is acceptable, provided that the air flows directly into the sampling tube holes.

1. If the tube is longer than the width of the air duct, drill a 3/4-inch hole in the duct directly opposite the hole already cut for the inlet tube. If the tube is shorter than the width of the air duct, install the end plug into the inlet tube. Sampling tubes over 3 ft. long must be supported at the end opposite the duct detector.

2. Slide the tube into the centermost housing bushing. Position the tube so that the arrows point into the air flow.

3. Secure the tube flange to the housing bushing with two #6 self-tapping screws.

4. For tubes longer than the width of the air duct, the tube should extend out of the opposite side of the duct. If there are more than 2 holes in the section of the tube extending out of the duct, select a different length using Table 1. Otherwise, trim the end of the tube protruding through the duct so that 1 to 2 inches of the tube extend outside the duct. Plug this end with the end plug and tape closed any holes in the protruding section of the tube. Be sure to seal the duct when the tube protrudes.

WARNING: In no case should more than 2 air inlet holes be cut off the tube. There must be a minimum of 10 holes in the tube exposed to the air stream.

NOTE: To install inlet tubes in ducts more than 8 feet wide, work must be performed inside the air duct. Sampling of air in ducts wider than 8 feet is accomplished by using the ST-10 inlet sampling tube. If the tube is shorter than the width of the air duct, install the end plug into the inlet tube and support the end opposite the duct detector.

Install the inlet tube as follows:

1. Drill a 3/4-inch hole in the duct directly opposite the hole already drilled for the inlet tube.

2. Slide the inlet tube with the flange into the centermost housing bushing. Position the tube so that the arrows point into the air flow. Secure the tube flange to the housing bushing with two #6 self-tapping screws.

3. From inside the duct, couple the other section of the inlet tube to the section already installed using the 1/2-inch conduit fitting supplied. Make sure that the holes on both of the air inlet tubes are lined up and facing into the air flow.

4. Trim the end of the tube protruding through the duct so that 1 to 2 inches of the tube extend outside the duct. Plug this end with the end plug and tape closed any holes in the protruding section of the tube. Be sure to seal the duct when the tube protrudes.

An alternate method to using the ST-10 is to use two ST-5 inlet tubes. Remove the flange from one of the tubes and install as described above. After the installation, use electrical tape to close off some of the sampling holes so that there is a total of 10 to 12 holes spaced as evenly as possible across the width of the duct.

Air currents inside the duct may cause excessive vibration, especially when the longer sampling tubes are used. In these cases a 3 inch floor flange (available at most plumbing supply stores) may be used to fasten the sampling tube to the other side of the duct. When using the flange/connector mounting technique, drill a 1 inch to 1-1/4-inch hole where the flange will be used.

There may be applications where duct widths are not what is specified for the installation. In such cases, it is permissible to modify an inlet sampling tube that is longer than necessary to span the duct width.

Use a 0.193-inch diameter (#11) drill and add the appropriate number of holes so that the total number of holes exposed to the air flow in the duct is 10 to 12. Space the additional holes as evenly as possible over the length of the tube.

All wiring must be installed in compliance with the National Electrical Code and the local codes 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.

For signal wiring, (the wiring between interconnected detectors or from detectors to auxiliary devices), it is usually recommended that single-conductor wire be no smaller than 18 gauge. The duct detector terminals accommodate wire sizes up to 14 gauge. The last foot of conduit should be flexible steel conduit, which facilitates installation and puts less strain on the conduit holes in the housing. Solid conduit connections may be used, if desired.

Smoke detectors and alarm system control panels have specifications for allowable loop resistance. Consult the control panel manufacturer’s specifications for the total loop resistance allowed for the particular model control panel being used before wiring the detector loop.

Wiring connections are made by stripping about 3/8-inch of insulation from the end of the wire, sliding the bare end under the plate, and tightening the clamping plate screw.

CAUTION: Do not loop wire under terminals when wiring detectors. Break wire runs to provide system supervision of connections.

To install the sampling tube filters, simply push the filter adapter into the exhaust tube, and push the filter onto the adapter tube on the left. Install the other filter over the end of the inlet sampling tube.

Filters require periodic cleaning or replacement, depending on the amount of dust and dirt accumulated. Visually inspect the filters at least quarterly; inspect them more often if the dust accumulation warrants it. See Section [6] for more information. Replacement filters can be ordered from System Sensor (Exhaust tube/intake tube filter P/N F36-05-00).

1. Perform the STANDBY AND TROUBLE TEST per Section [6.2.1].

2. Perform the MAGNET TEST per Section [6.2.2.1]. The RTS451 test of Section [6.2.2.2] may substitute for this requirement.

3. Perform the AIR FLOW TEST per Section [6.1.1].

4. Perform the SMOKE RESPONSE TEST per Section [6.1.2].

5. Perform the SENSITIVITY TEST per Section [6.2.3].

6. Record all test results in the Detector Test Log at the end of this manual.

Install the cover using the four screws that are fixed in the housing cover. Be certain filters are installed as specified in Section [5.6]. Make sure that the cover fits into the base groove and that all gaskets are in their proper positions. Tighten the four screws to 10 in-lbs.

Test and maintain duct detectors as recommended in NFPA 72. The tests contained in this manual were devised to assist maintenance personnel in verification of proper detector operation.

Before conducting these tests, notify the proper authorities that the smoke detection system will be temporarily out of service. Disable the zone or system under test to prevent unwanted alarms.

After conducting these tests, record the appropriate information in the Detector Test Log at the end of this manual.

To verify sufficient sampling of ducted air, use a manometer to measure the differential pressure created from air flow across the sampling tubes. The pressure should measure no less than 0.01 inches of water and no greater than 1.20 inches of water.

To determine if smoke is capable of entering the sensing chamber, visually identify any obstructions. Plug the exhaust and inlet tube holes to prevent ducted air from carrying smoke away from the detector head, then blow smoke such as cigarette, cotton wick, or punk directly at the head to cause an alarm. REMOVE THE PLUGS AFTER TESTING OR THE DETECTOR WILL NOT FUNCTION PROPERLY.

The filters do not substantially affect smoke behavior even when they are up to 90% clogged. Quarterly visual inspection is usually often enough to determine if filters should be replaced because only a high percentage of contamination affects duct detector performance.

Standby: Check for the presence of the blinking red LEDs (blinks about every 10 seconds) through the transparent housing cover. If the APA451 accessory is used, its green Power LED should be illuminated continuously.

Trouble: If the detector LEDs do not blink or if the APA451 Power LED is not illuminated, the detector lacks power (check wiring, panel, or power supply), the head is missing (install), or the unit is defective (return for repair).

Test: The trouble condition can be caused intentionally to verify correct operation of the system. Remove power to the unit, remove the detector head, or place the M02-04-00 magnet into the Reset locator. These actions should cause a trouble condition locally and at the system control panel.

1. Place the painted surface of the magnet into the Test locator molded into the side of the housing.

2. The red alarm LEDs on the detector should latch on, as should any accessories (PA400, RA400Z, RTS451, APA451). Verify auxiliary functions (such as fan shutdown) and system control panel alarm status.

3. Place the painted surface of the magnet into the Reset locator molded into the side of the housing. This should clear the latched alarm condition at the detector. If a system control panel is used, the panel may also require resetting.

The RTS451/RTS451KEY Remote Test Station facilitates test of the alarm capability of the duct detector as indicated in the RTS451/RTS451KEY manual. The DH400ACDC duct detector can be reset by the RTS451/RTS451KEY. If a system control panel is used, the panel itself may also require resetting.

To install the RTS451/RTS451KEY, connect the device as shown in Figure 8; wire runs must be limited to 25 ohms or less per interconnecting wire. Place the coil in the detector housing with the arrow facing up and pointing toward the detector. Attach the coil leads to the housing terminals as shown; polarity is not important. Firmly screw the bracket in place over the test coil.

After verification of alarm capability, use the MOD400R test module with a voltmeter to check detector sensitivity as described in the test module’s manual. The housing cover must be removed to perform this test.

If test module readings indicate that the detector head is outside of the acceptable range that is printed on the back of the detector head, the detector head requires cleaning per Section [7].

After verification of alarm capability, the R59-18-00 test card may be used to verify correct sensitivity of the detector head.

1. Remove the duct housing cover.

2. Remove the detector head from the housing.

3. Remove the detector head cover by placing a small blade screwdriver in the side slot of the detector cover, twisting it slightly until the cover can be turned counterclockwise.

4. Carefully reinsert the detector head into the duct housing and wait 50 seconds for power up. Do not hold the swirl chamber to twist the detector head.

5. Insert the NO ALARM end of the test card into the test slot and slide it counterclockwise until it stops. The detector should not alarm after 20 seconds.

6. Remove the card and then insert the ALARM end into the slot and slide it counterclockwise until it stops. The LEDs should latch on within 20 seconds. Remove card and reset detector.

7. Put the cover back by gently rotating it clockwise until it locks in place. Secure the duct housing cover using the 4 cover screws.

Notify the proper authorities that the smoke detector system is undergoing maintenance, and that the system will be temporarily out of service. Disable the zone or system undergoing maintenance to prevent unwanted alarms and possible dispatch of the fire department.

1. Turn off power to the system.

2. Remove and inspect the sampling tube filters.

3. If the filters are heavily coated with dirt, replace them with new filters. If they are not heavily coated, use a vacuum cleaner or compressed air nozzle to remove dust, then reinstall the filters.

1. Remove the detector cover by inserting a small bladed screwdriver into the slot located 90 degrees from the field test port. Rotate the cover counterclockwise to remove.

2. Lift the screen from the photo chamber. Vacuum the screen and cover before using clean, compressed air to loosen and blow out any remaining debris. Replacement screens (RS24) are available.

3. Vacuum the photo chamber. Use clean compressed air to blow it clean.

4. Replace the screen by aligning the arrow on top with the field test port on the detector. Press the screen into place. It should fit tightly on the chamber.

5. Replace the detector cover and rotate it clockwise to lock it in place.

1. Remove the detector cover by depressing the three lock prongs on the top of the cover and rotating the cover counterclockwise to remove the cover and screen assembly. The optional CRT400 Cover Removal Tool makes cover removal easier.

2. Carefully pull the screen out of the cover.

3. Clean the screen thoroughly with a soft brush or vacuum. Replacement screens (RS14) are available.

4. Brush or vacuum the inside of the cover. The cover may then be blown out with clean, compressed air.

5. Vacuum the sensing chamber before using clean, compressed air to loosen and blow out any remaining debris.

6. Press the screen back into the cover.

7. Replace the detector cover onto the sensing chamber. Rotate it clockwise to lock it into place.

1. Reinstall the detector in its housing.

2. Restore system power.

3. Perform Detector Check, Section [5.7].

4. Notify the proper authorities testing has been completed and the smoke detector system is back in operation.

Environmental Limits

Temperature: 32°F to 120°F (0°C to 49°C)

Humidity: 10% to 93% R.H. non-condensing

Air Velocity: 500 to 4000 Ft/min. (1.5 to 20.3 m/sec.)

Mechanical Specifications

Length: 14.5 inches (37 cm)

Width: 5 inches (13 cm)

Depth (installed): 4 inches (10 cm)

Weight: 4 pounds (1.8 kg)

Terminals

Captive universal terminal screws with sems plates accept wire sizes of 14 gauge or smaller. The screws can withstand 10 in-lbs of tightening torque without damage.

MOD400R: Sensitivity Test Module

RA400Z: Remote Annunciator

RTS451/RTS451KEY: Remote Test Station, test & reset switch with alarm LED

PA400: Piezo Sounder

APA451: Annunciator with piezo, alarm & power LEDs

CRT400: Cover Removal Tool (Ion only)

F36-05-00: Replacement Air Filter (two per package)

M02-04-00: Replacement Test Magnet

P48-21-00: Replacement End Plug for inlet sampling tube

R59-18-00: Replacement Calibrated Test Card (For photo units only)

RS14: Replacement Screen, Ion

RS24: Replacement Screen, Photo

A2650-01: Replacement Installation Kit (mounting hardware)

Sampling (Inlet) Tubes

ST-1.5: 1 to 2 feet (0.3 to 0.6 m)

ST-3: 2 to 4 feet (0.6 to 1.2 m)

ST-5: 4 to 8 feet (1.2 to 2.4 m)

ST-10: 8 to 12 feet (2.4 to 3.7 m)

Exhaust Tube Extension

A2440-00: 5.75 in. (14.6 cm.) additional

The following information should be recorded:

Detector Identification Information:

– Manufacturer and Detector Model – Serial Number – Date Installed – Description of Detector Location

Test Results and Maintenance Data:

– Date Tested – Test Description – Test Results – Maintenance Performed – Comments