Data Sheet - System Sensor

High Sensitivity
Duct Smoke Detector
The System Sensor DNRHS detector provides very early
warning fire protection in interior duct applications with
high-velocity, high-volume air changes.
• Temperature range 32°F to 100°F (0°C to 38°C)
• Air velocity rating from 300 to 4,000 FPM
• 24 VDC operation
• Versatile mounting options: square or rectangular configuration
• P
atented sampling tube installs from the front or back of the
detector with no tools required
• New cover tamper signal
• Increased wiring space with a newly added 3/4-inch conduit knockout
• Clear cover for convenient visual inspection
• Remote testing capability (DCOIL included)
• E
asily mounts to round or rectangular ducts from
1 to 12 feet (0.3 to 3.7 m) wide
• 3 year warranty
The DNRHS high sensitivity duct smoke detector provides very
early warning of fires* to protect high-value assets and mission
critical operations from fire and the spread of damaging smoke
through air management systems. The detector’s intelligent laser
sensor can detect miniscule amounts of smoke (0.02 percent-perfoot) flowing through ductwork at air velocities from 300 to 4,000 feet
per minute — ideal for environments with high-velocity, high-volume
air changes.
Some ideal applications for the DNRHS include telecommunications
switching facilities, cellular telephone infrastructure, integrated circuit
fabrication facilities, computer rooms, and clean rooms.
Like all InnovairFlex™ duct smoke detectors, the DNRHS includes
several features designed to lower installation time and costs.
Its pivoting housing converts to both square and rectangular
configurations to fit a variety of installation footprints. Its tool-free
sampling tubes plug into the detector from the front or back without
the need for set screws, which can be easy to lose. In addition,
the twist-in, twist-out 7251 high sensitivity laser smoke detector
head enables easy removal for quick cleaning, maintenance, and
*The DNRHS high sensitivity duct smoke detector is designed to satisfy
NFPA 76 for Very Early Warning Fire Protection. NFPA 76, Section Very Early Warning Fire Protection, calls for sensors to be
mounted at the return air location for a space in the following instances:
Agency Listings
(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 m2 (4 ft2) of the return air opening.”
System Sensor provides system flexibility for duct smoke detector applications with a variety of accessories, including two remote test
stations and several different means of visible and audible system annunciation. As with our duct smoke detectors, all duct smoke detector
accessories are UL listed.
(UL S2522)
(UL S2522)
(UL S2522)
DNRHS Duct Smoke Detector Specifications
Architectural/Engineering Specifications
The high sensitivity air duct smoke detector shall be a System Sensor Model DNRHS 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 to 4,000 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. The flexible
housing of the duct smoke detector shall fit both square and rectangular footprints. The detector shall be capable of local testing via magnetic
switch or remote testing using the RTS151KEY or RTS151 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 feet wide without
adapter brackets. 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 12 to 18 AWG wiring.
Physical Specifications
Size: (Rectangular)
14.38 in (37 cm) Length; 5 in (12.7 cm) Width; 2.5 in (6.35 cm) Depth
7.75 in (19.7cm) Length; 9 in (22.9 cm) Width ; 2.5 in (6.35 cm) Depth
Shipping Weight
2.0 lbs (1.2 kg)
Operating Temperature Range
32°F to 100°F (0°C to 38°C)
Storage Temperature Range
–22°F to 100°F (–30°C to 38°C)
Operating Humidity Range
10% to 93% relative humidity
Air Duct Velocity
300 to 4,000 ft/min (0.5 to 20.32 m/sec)
Electrical Specifications
24 VDC
Power supply voltage
15 to 32 VDC
Current Requirements (Using No Accessories)
Max. standby current
230 μA @ 24 VDC (without communication); 330 μA @ 24 VDC (one communication every 5 sec with LED enabled)
Max. alarm current
6.5 mA (LED on)
Ordering Information
Part No.
High sensitivity duct smoke detector
High sensitivity duct smoke detector (Canadian model)
Replacement intelligent laser sensor head
Metal sampling tube duct widths up to 1 ft (0.3 m)
Metal sampling tube duct widths 1 to 2 ft (0.3 to 0.6 m)
Metal sampling tube duct widths 2 to 4 ft (0.6 to 1.2 m)
Metal sampling tube duct widths 4 to 8 ft (1.2 to 2.4 m)
Metal sampling tube duct widths 8 to 12 ft (2.4 to 3.7 m)
End cap for metal sampling tubes
*(A) suffix denotes Canadian products
3825 Ohio Avenue • St. Charles, IL 60174
Phone: 800-SENSOR2 • Fax: 630-377-6495
Metal exhaust tube duct width 1 ft (0.3 m)
Test magnet
Remote test station
Remote test station with key
Remote annunciator alarm LED
Remote test coil (included)
©2012 System Sensor.
Product specifications subject to change without notice. Visit
for current product information, including the latest version of this data sheet.
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