Simplex 4098-9747 — the CO Replacement Cartridge (CORC), the field-replaceable carbon monoxide sensing element for Simplex TrueAlarm CO sensor bases.
Carbon monoxide sensing is not like photoelectric smoke sensing. A TrueAlarm photoelectric sensor is continuously calibration-checked and drift-compensated by the panel, so it can stay in service for as long as it tests clean. An electrolytic CO cell cannot be tested or compensated that way, so Johnson Controls gives it a fixed operational lifetime tracked by a date code built into the CO sensor module electronics, and the panel counts it down. The 4098-9747 is what you fit when that count runs out. The control unit gives ample warning first: an Almost Expired trouble appears twelve months out and again at six months, so replacement can be planned into a service visit rather than sprung on you, and a TrueAlarm CO service report lists each sensor's current ppm reading, end-of-life date and state. The cartridge is reached by removing the interchangeable sensor head above it — that head is tamper-monitored, so its removal will itself raise a trouble at the panel.
Specifications
| Product type |
CO Replacement Cartridge (CORC), field-replaceable electrolytic carbon monoxide sensing element |
| Compatible bases |
4098-9770 CO Base, standard operation; 4098-9771 CO Base with sounder |
| Service life |
10 year operational lifetime with 4007ES, 4010ES and 4100ES control units; 5 years with 4100U control units |
| Life tracking method |
Date code built into the CO sensor module electronics, counted at the fire alarm control unit |
| Replacement warnings |
Almost Expired trouble at 12 months and again at 6 months before end of life, then an Expired (End of Life) trouble |
| Reported CO sensor troubles |
Disabled; Almost expired 12 months; Almost expired 6 months; Expired (End of Life); Short; Sensor missing or failed |
| UL 2034 / CSA 6.19-01 response time |
70 ±5 ppm: 60 to 240 minutes · 150 ±5 ppm: 10 to 50 minutes · 400 ±10 ppm: 4 to 15 minutes |
| UL 2034 / CSA 6.19-01 false alarm resistance |
30 ±3 ppm: no alarm for 30 days · 70 ±5 ppm: no alarm for 60 minutes |
| CO level tracking |
Levels above 40 ppm are time-integrated at the control unit to determine the alarm point; levels below 40 ppm are not tracked |
| Access |
Remove the interchangeable sensor head, which features tamper monitoring; sensor removal causes a trouble condition |
| Replacement instructions |
CORC Replacement Instructions, document 579-791 |
| System listings (host base) |
UL 268 and UL 2075, allowing systems to be listed to UL 2034; ULC listed to CSA 6.19-01; FM approved; CSFM Listing 7300-0026:330 |
Installation notes
-
Expired does not mean dead, but it does mean replace. Johnson Controls states that although the CO sensor continues to function after the Expired trouble is indicated, replacement is required to ensure proper detection accuracy.
-
Life depends on the panel, not the cartridge. The same element is tracked over a 10 year life on 4007ES, 4010ES and 4100ES control units but only 5 years on a 4100U. Plan replacement cycles from the panel type in the building.
-
Expect a trouble while you work: lifting the sensor head to reach the cartridge trips the tamper monitoring, so the panel should be placed in the appropriate service state before the head comes off.
-
Follow 579-791: CO cartridge installation and replacement is covered by its own instruction document, separate from the sensor base installation instructions (574-707).
-
Verify afterwards: the panel's CO test mode disables the multi-sensor analysis algorithms so the CO element can be functionally tested on its own, using a Solo Model 332 aerosol dispenser with the Solo C3 CO aerosol canister, or equivalent.
-
Check the service report: the TrueAlarm CO service report lists current concentration in ppm, end-of-life date and current state for every CO sensor programmed in the panel — the quickest way to find which cartridges are due.
Related models
-
4098-9770 — TrueAlarm CO sensor base, standard operation, powered from the IDNet channel
-
4098-9771 — TrueAlarm CO sensor base with integral piezoelectric sounder; requires separate 24 VDC or NAC power
-
Solo 332 / Solo C3 — aerosol dispenser and CO aerosol canister used for functional CO testing
-
4098-9714 / 4098-9764 / 4098-9733 — the photoelectric, photo/heat multi-sensor and heat sensor heads that sit above the cartridge in a CO base
Specifications taken from the Johnson Controls / Simplex data sheet "Multi-Point Peripherals — TrueAlarm CO Sensor Bases for Smoke, Heat, and Photo/Heat Sensors using IDNet Communications," document S4098-0052 Rev. 6 (05/2025). Manufacturer specifications are subject to change without notice.
