Edwards SIGA-OSD Intelligent Optical Smoke Detector

The Edwards SIGA-OSD Intelligent Optical Smoke Detector is an addressable fire detection device that uses advanced optical sensing technology to detect smoke while helping distinguish actual fire signatures from nuisance sources. Edwards currently identifies the SIGA-OSD as its Signature Optica Smoke Detector.

The detector gathers analog information from multiple optical sensors and converts it into digital signals. Dual optical wavelengths, multiple detection angles, and onboard digital filtering help distinguish smoke from non-fire particles such as common cooking particulates.

Product Functions

• Provides intelligent addressable smoke detection
• Uses multi-criteria optical sensing
• Uses multiple optical sensors
• Uses dual optical wavelengths
• Provides nuisance-alarm rejection
• Supports electronic addressing
• Provides automatic device mapping
• Offers five sensitivity settings
• Provides twenty pre-alarm settings
• Supports automatic day/night sensitivity adjustment
• Provides two levels of environmental compensation
• Provides two dirty-detector warning levels
• Includes continuous self-diagnostics
• Provides non-volatile memory
• Uses a bi-color green/red status LED
• Supports standard, relay, isolator, and audible bases

Multi-Criteria Optical Detection

The SIGA-OSD uses multi-criteria optical smoke sensing rather than relying on a single optical measurement.

Its sensing architecture combines dual optical wavelengths with multiple detection angles. The detector’s onboard microprocessor analyzes these readings and applies digital filtering before making an alarm decision.

This technology helps the detector recognize particle characteristics associated with an actual fire while rejecting patterns more typical of nuisance sources.

Nuisance Alarm Rejection

A key feature of the SIGA-OSD is its integrated nuisance-rejection capability.

Edwards specifically states that the detector is designed to reduce unwanted alarms caused by general cooking particulates.

This makes the SIGA-OSD useful where reliable smoke detection is required but ordinary airborne particles could otherwise contribute to nuisance alarms.

Smoke Sensitivity

The published smoke sensitivity range is:

0.5 to 4.36%/ft obscuration

or

1.6 to 13.6%/m obscuration.

The detector provides:

Five sensitivity settings

and

Twenty pre-alarm settings.

Available sensitivity and pre-alarm functions may depend on the capabilities and programming of the connected Edwards control system.

Environmental Compensation

The SIGA-OSD provides automatic environmental compensation to help maintain stable detection performance as environmental conditions and detector contamination gradually change.

Edwards specifies:

Two levels of environmental compensation

and

Two levels of dirty-detector warning.

These features allow maintenance conditions to be identified before contamination significantly affects detector performance.

Automatic Day/Night Sensitivity

The SIGA-OSD supports automatic day/night sensitivity adjustment.

When supported by the connected control system, detector sensitivity can be adjusted according to programmed operating periods, providing additional flexibility for locations where environmental conditions change during occupied and unoccupied hours.

Electronic Addressing

The SIGA-OSD uses electronic addressing rather than conventional rotary or DIP address switches.

It also supports Edwards Automatic Device Mapping, helping the Signature system identify device locations and relationships on the signaling circuit.

Edwards documentation states that Signature systems can support up to 250 total Signature addresses per loop, subject to the capabilities of the specific control system.

LED Status Indication

The detector incorporates a bi-color status LED.

Normal: Green LED flashes

Alarm/Active: Red LED flashes.

The indicator provides local confirmation of detector communication and alarm status.

Compatible Detector Bases

The SIGA-OSD supports several Edwards detector-base configurations:

SIGA-SB / SIGA-SB4 — Standard bases

SIGA-RB / SIGA-RB4 — Relay bases

SIGA-IB / SIGA-IB4 — Fault isolator bases

SIGA-AB4G — Audible base

SIGA-AB4G-LF — Low-frequency audible base

SIGA-AB4GT — Audible base for CO and/or fire applications.

This allows the same detector to support standard, relay, isolation, and local audible applications.

Electrical & Detection Information

Operating Voltage: 15.20–19.95 VDC

Normal Operating Current: 32 µA

Alarm Current: 45 µA

Smoke Sensitivity: 0.5–4.36%/ft obscuration

Air Velocity: 0–4,000 ft/min / 0–20 m/s

Environmental Compensation: Automatic

Status Indicator: Green/Red LED.

The detector communicates its status through the compatible Edwards Signature signaling circuit rather than using a conventional standalone alarm contact.

Installation Information

The SIGA-OSD installs onto a compatible Edwards Signature detector base. The base is wired first, after which the detector head is attached and electronically configured within the fire alarm system.

For wall installations, Edwards specifies mounting no more than:

12 inches / 305 mm below the ceiling.

Compatible detector test equipment includes:

Testifire 1000

Testifire 2000.

Installation, spacing, programming, and testing should follow the SIGA-OSD installation sheet and the requirements of the compatible Edwards fire alarm control system.

SIGA-OSD Datasheet