System Sensor 2151 smoke detector (replaces 2451TH) — a low-profile plug-in photoelectric smoke detector head, just 1.66″ (42 mm) high, for conventional fire alarm systems. The head plugs into a B100LP Series adapter base, ordered separately, which determines the wiring configuration and operating voltage.
The 2151 photoelectric smoke detector contains a unique optical sensing chamber designed to sense the presence of smoke particles produced by a wide range of combustion sources. A custom integrated circuit incorporates signal processing to help reduce false alarms. The sensing chamber is sealed against back pressure air flow, dirt and insects, and is protected by a fine mesh screen which can be cleaned or replaced; the cover is removable for field cleaning. Two LEDs blink in standby mode, providing 360° visibility, and a built-in magnetic test switch supports functional testing. The 2151 shares the same sleek low-profile housing and the same adapter bases as the 1151 ionization head, so photoelectric and ionization heads are interchangeable on an installed base. The detector is aesthetically suited to commercial and institutional interiors and offers a built-in tamper-resistant feature and an optional remote LED.
Specifications
| Model |
2151 |
| Sensing technology |
Photoelectric (optical sensing chamber) |
| Sensitivity |
3% ± 0.7%/ft |
| Standby current |
85 µA |
| Operating voltage / alarm current |
Mounting-base dependent (see base table below) |
| Air velocity |
0 – 3,000 ft. (914.4 m)/min. |
| Operating temperature |
32°F to 120°F (0°C to 49°C) |
| Humidity range |
10 – 93% RH non-condensing |
| Height |
1.66″ (42.164 mm) |
| Diameter |
4.1″ (104.14 mm) with unflanged base; 6.1″ (154.94 mm) with flanged base |
| Weight |
3.6 oz. (102 g) |
| Construction |
Flame-retardant thermoplastic |
| Certification |
Certified to UL 268 |
Installation notes
-
Base required and sold separately: the 2151 is a detector head that requires a B100LP Series base. The base — not the head — determines loop type, nominal voltage and alarm current.
-
Base electrical data: B110LP, 2-wire, 12/24 VDC, 10 to 100 mA alarm; B110RLP, 2-wire, 24 VDC with current-limit resistor, 22 to 62 mA; B112LP, 4-wire, 24 VDC, Form-A & -C, 14 to 39 mA; B114LP, 4-wire, 120 VAC, Form-A & -C plus A supervisory, 75 mA AC maximum; B116LP, 2-wire, 24 VDC, Form-C, 12 to 100 mA; B401 flangeless, 2-wire, 12/24 VDC, 10 to 100 mA.
-
Panel must limit alarm current: on the B110LP, B116LP and B401 bases the alarm current must be limited by the control panel.
-
Sensitivity testing: the detector supports field sensitivity metering to meet the NFPA 72 requirement. The MOD400R test tool is used with most analog or digital multimeters.
-
Junction boxes: B401 accepts a 50 mm or 60 mm box; B110LP/RLP accept single-gang, 3½″, 4″ octagonal or 4″ square; B112LP and B116LP add 50 mm, 60 mm and 75 mm; B114LP requires a 4″ octagonal or 4″ square box.
-
Relay contact ratings (resistive or inductive at 60% power factor): Form-A 2.0 A at 30 VAC/DC; Form-C 0.6 A at 110 VDC, 2.0 A at 30 VDC, 1.0 A at 125 VAC, 2.0 A at 30 VAC.
Replacement
The 2151 replaces the 2451TH, so keep both part numbers in mind when matching an older spec or job record. The 2151 is a detector head only and needs a B100LP Series base, ordered separately, such as the B110RLP.
Related models
-
1151 — the ionization head in the same housing, on the same bases: 40 µA standby, 1.9% ± 0.62%/ft sensitivity, and a lower 0–1,200 ft/min air velocity rating
-
B110LP / B401 — 2-wire bases, 12/24 VDC (B401 is flangeless)
-
B112LP — 4-wire base, Form-A & -C, 24 VDC
-
B114LP — 4-wire base, Form-A & -C plus A supervisory, 120 VAC
-
B116LP — 2-wire base, Form-C, 24 VDC
-
B401BH — sounder base; requires an external 24 VDC supply and a 4″ square electrical box
-
RA400Z — remote annunciator for two- or four-wire systems, 3–32 V, fits a standard single-gang box
Specifications taken from the Fire•Lite Alarms / System Sensor data sheet “1151 and 2151 Low-Profile Plug-In Photoelectric and Ionization Smoke Detectors,” document DF-51483 (June 30, 1998). Manufacturer specifications are subject to change without notice.
Documents
FAQ
Is a base included with the 2151?
No. The 2151 is a detector head that plugs into a B100LP series base, such as the B110LP, B112LP, B114LP, B116LP or B401, ordered separately.
What is the sensitivity of the 2151?
3% ± 0.7% per foot obscuration.
Can it be swapped with an ionization head?
Yes. The 2151 photoelectric head and the 1151 ionization head share the same low-profile housing and the same bases.
How is it tested in the field?
It has a built-in magnetic test switch for functional testing.
