7251DH
High Sensitivity
Duct Smoke Detector
The System Sensor 7251DH detector is designed for
interior duct applications where high velocity, high
volume air changes are required for very early warning
fire protection.
Features
•
Temperature range 32°F to 100°F (0°C to 38°C)
•
Air velocity rating from 300 to 4,000 FPM
•
24 VDC operation
•
Easy and quick mounting to round or rectangular ducts from
1 ft to 12 ft (0.3 m to 3.7 m) wide
•
3 year warranty
The 7251DH
high sensitivity duct smoke detector provides
dependable performance for management of fans, blowers, and
air conditioning systems by using an intelligent laser smoke sensor
residing in an efficient housing design that samples air currents
passing through a duct. The twist-in, twist-out 7251 high sensitivity
laser smoke detector head allows easy removal for quick cleaning,
maintenance, and replacement without removing the duct housing.
The laser detector achieves sensitivities as low as 0.02 percent-per-
foot by using a laser diode instead of a standard LED light source
in the sensing chamber. Many sensitive areas cannot tolerate even
small amounts of smoke. This 7251DH detector is designed to
protect valuable assets and operations where systems must remain
online at all times.
Some ideal applications for the 7251DH high sensitivity duct smoke
detector include:
– Telecommunications switching facilities
– Cellular telephone infrastructure
– Integrated circuit fabrication facilities
– Computer rooms
– Clean rooms
NFPA 76, Section 8.5.3.1.2.3 Very Early Warning Fire Protection,
calls for
sensors to be mounted at the return air location for a space in the
following instances.
(A) “Where stand-alone packed HVAC units are installed, sensors or
ports shall be installed where return air is brought back to the unit.”
(B) “Sensors or ports shall be installed such that each covers no
greater than 0.4 m
2
(4 ft
2
) of the return air opening.”
The System Sensor 7251DH high sensitivity duct smoke detector is
designed to satisfy NFPA 76 for Very Early Warning Fire Protection.
Agency Listings
S911
Accessories
System Sensor provides system flexibility with a variety of accessories, including two remote test stations, and several different means of
visible and audible system annunciation. As with our duct detectors, all duct smoke detector accessories are UL listed.
RTS451KEY
Remote Test Station
with Key (UL S2522)
PA400W
Piezo Sounder
(UL S3593)
RTS451
Remote Test Station
(UL S2522)
RA400Z
Remote Annunciator
(UL S2522)
7251DH Duct Smoke Detector Specifications
Architectural/Engineering Specifications
The high sensitivity air duct smoke detector shall be a System Sensor Model 7251DH high sensitivity duct smoke detector. The detector shall be UL listed per UL
S911, Standard for Smoke Detectors for Duct Applications, specifically for use in air handling systems. The detector shall operate at air velocities from 300 feet
per minute to 4000 feet per minute. The detector shall have an operating temperature range of 32˚F to 100˚F. The detector housing shall be equipped with an
integral mounting base capable of accommodating laser smoke detector heads. It shall be capable of local testing via magnetic switch or remote testing using
the RTS451KEY or RTS451 Remote Test Station. The duct detector housing shall incorporate an airtight smoke chamber in compliance with UL S911. The housing
shall be capable of mounting to rectangular or round ducts up to 12 ft wide without adapter brackets. An integral filter system shall be included to reduce dust
and residue effects on detector and housing, thereby reducing maintenance and servicing. Sampling tubes shall be installed after the housing is mounted to
the duct by passing through the duct housing. Terminal connections shall be of the strip and clamp method suitable for 14 to 18 AWG wiring.
Physical Specifications
Size
Shipping Weight
Operating Temperature Range
Storage Temperature Range
Operating Humidity Range
Air Duct Velocity
Electrical Specifications
Voltage
24 VDC
Power supply voltage
15 to 32 VDC
Current Requirements (Using No Accessories)
Max. standby current
Max. alarm current
230
μA
@ 24 VDC (without communication); 330
μA
@ 24 VDC (one communication every 5 sec with LED enabled)
6.5 mA (LED on)
14½ in L × 5 in W × 4 in D (36.8 cm L × 12.7 cm W × 10.2 cm D)
2.8 lbs (1.1 kg)
32°F to 100°F (0°C to 38°C)
–22°F to 100°F (–30°C to 38°C)
10% to 93% relative humidity
300 to 4000 ft/min (0.5 to 20.32 m/sec)
Ordering Information
Part No.
7251DH
7251DHA
7251
Accessories
ST-1.5
ST-3
ST-5
ST-10
P48-21-00
Description
High sensitivity duct smoke detector
High sensitivity duct smoke detector (Canadian model)
Replacement intelligent laser sensor head
Metal sampling tube duct widths 1 ft to 2 ft (0.3 m to 0.6 m)
Metal sampling tube duct widths 2 ft to 4 ft (0.6 m to 1.2 m)
Metal sampling tube duct widths 4 ft to 8 ft (1.2 m to 2.4 m)
Metal sampling tube duct widths 8 ft to 12 ft (2.4 m to 3.7 m)
End cap for metal sampling tubes
RTS451
PA400W(A)
RA400Z(A)
F36-05-00
M02-04-00
A2650-01
Remote test station
Piezo sounder (white)
Remote annunciator alarm LED
Replacement air filters (two per package)
Test magnet
Replacement installation kit (mounting hardware)
RTS451KEY(A)* Remote test station with key
*(A) suffix denotes Canadian products
3825 Ohio Avenue • St. Charles, IL 60174
Phone: 800-SENSOR2 • Fax: 630-377-6495
©2007 System Sensor.
Product specifications subject to change without notice. Visit systemsensor.com for
current product information, including the latest version of this data sheet.
A05-0427-000 • 8/07 • #1859
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