When a fire alarm detector fails or reaches end of life, the first challenge technicians and facilities managers face is identifying the exact model number. Order the wrong part and you waste time and money. This guide walks you through exactly where to find model numbers, how to decode manufacturer part numbers, and what to do when the label is missing.
Where Are Model Numbers Located on Fire Alarm Detectors?
Fire alarm detectors have two primary components: the base (mounting cup) and the head (sensing element). Model numbers are typically found on both—but in different places.
- Detector head: Look for a label or molded text on the underside of the sensing head. On most modern detectors, the model number is printed on a white sticker near the contacts or stamped into the plastic housing.
- Detector base: The base usually carries its own separate part number, since bases and heads are often sold and replaced independently. Check the inside rim or the underside of the base for a printed label or embossed text.
- Circuit board: If the external label is gone, the PCB inside the detector often has the part number silk-screened directly onto the board. This requires removing the head from the base.
Always record both the head and base model numbers. Many systems use proprietary bases that only accept certain detector heads—mixing brands or mismatched generations will cause supervisory faults.
Decoding Simplex Part Numbers
Simplex (now part of Johnson Controls) uses a consistent part numbering format: four digits, a dash, and four digits. For example, 4098-9714 is a TrueAlarm photoelectric sensor head, while 4098-9792 is the analog sensor base designed to work with it.
The first four digits often indicate the product family (4098 = detectors, 4906 = notification appliances, 4090 = modules). The second four digits identify the specific variant—sensitivity level, communication protocol, or mounting style. When searching for Simplex parts, always use the full 9-digit part number including the dash. Browse our full Simplex parts catalog to find compatible replacements.
Decoding Notifier Part Numbers
Notifier (a Honeywell brand) uses alphanumeric codes that incorporate the product type. FSP-851 is an intelligent low-profile photoelectric smoke detector; FSP-951 adds a thermal element. The prefix indicates function: FSP = photoelectric smoke, FCP = combination smoke/CO, B = base. The numeric suffix identifies the generation and feature set.
Notifier bases and heads must match by protocol generation. The B210LP base, for example, is designed for the 850/950 series. Mixing a 700-series detector with an 800-series base will typically cause a device fault. Visit our Notifier parts page for a complete listing.
Decoding Edwards EST Part Numbers
Edwards (now part of Carrier) uses the SIGA- prefix for its Signature series addressable devices. SIGA-PD is a photoelectric detector; SIGA-IP is an ionization/photoelectric combination; SIGA-HFS is a heat detector. The letters after SIGA indicate the sensing technology and feature set.
For older Edwards EST2 and EST3 panels, the SIGA-series detectors are backward compatible across generations. Always verify the loop protocol version before ordering. Find Edwards EST compatible devices on our Edwards brand page.
Decoding Siemens Part Numbers
Siemens fire alarm products (formerly Cerberus, now under Siemens Building Technologies) use a format like HFP-11 (high-frequency point detector) or DB-11 (detector base). The letter prefix identifies the product category; the numeric suffix identifies the generation. Siemens uses the SAFEDLINK and SAFENET protocols, so detector compatibility is tied to the panel generation.
What to Do When the Label Is Gone
Labels wear off, especially in dirty industrial environments. Here are your options when the model number is unreadable:
- Check the panel’s device list. Most modern addressable panels log the device type, address, and sometimes the part number during commissioning. Pull up the panel’s device list in the programmer or LCD interface.
- Look at adjacent detectors. In most installations, the same detector model is used throughout a zone. A readable label on a nearby unit tells you what you need.
- Match by physical profile. Photograph the detector and base, then compare to manufacturer product images. Many technicians can identify common detectors by form factor alone.
- Contact the installing contractor. The original installation drawings (as-builts) should list the detector model by zone or device address.
- Call us. Our team at Life Safety Consultants can often identify a detector from a photo or description. Browse our full parts catalog or contact us directly.
Pro Tips for Future Reference
Once you’ve identified your detectors, take steps to prevent this problem in the future. Use a permanent marker to write the part number on the inside of the base before reinstalling. Update your as-built drawings. Many facilities managers now photograph each device during annual inspections and store the images in their CMMS. Five minutes of documentation now saves hours of detective work later.
