Introduction
The Kidde Fire Sentry Smoke Detector, model i9040, is a compact, battery-operated unit designed to provide continuous protection against smoke and fire. Its 4-inch diameter allows for installation in various spaces, including homes, RVs, and mobile homes. This ionization smoke alarm is engineered to detect invisible fire particles associated with flaming fires, sounding an 85-decibel alarm upon detection. Powered by a 9-volt battery, it ensures operation even during power outages. Key features include a test-hush button for easy testing and silencing of nuisance alarms, and a red LED indicator for sensing smoke or fire. The unit also chirps to indicate when the battery needs replacement.

Figure 1: Front view of the Kidde Fire Sentry Smoke Detector.
Setup and Installation
The Kidde i9040 smoke detector is designed for easy, wire-free installation. Follow these steps to set up your device:
- Battery Installation: Open the battery compartment. Insert a fresh 9-volt alkaline battery, ensuring correct polarity. The device is powered by a 9-volt battery, providing coverage during power failures.

Figure 2: Inserting the 9-volt battery into the smoke detector.
- Mounting Bracket: Secure the mounting bracket to your desired location on the ceiling or wall using the provided screws. Ensure the bracket is firmly attached.

Figure 3: The mounting bracket for secure installation.
- Attach Detector: Align the smoke detector with the mounting bracket and twist clockwise until it locks securely into place.
- Initial Test: After installation, press and hold the Test-Hush button to ensure the alarm sounds. A red LED will indicate sensing.
Installation Video
Video 1: Official Kidde Battery-Operated Smoke Detector Alarm overview and installation guide.
Operating Instructions
The Kidde i9040 smoke detector operates automatically once the battery is installed. Familiarize yourself with its key functions:
- Alarm Sound: When smoke or fire is detected, the unit will emit an 85-decibel alarm.
- Red LED Indicator: A red LED light will illuminate when the smoke detector is sensing smoke or fire.
- Test-Hush Button: This button serves two primary functions:
- Test: Press and hold the button to test the alarm's circuitry, horn, and battery function. The alarm should sound briefly.
- Hush: In case of nuisance alarms (e.g., from cooking or shower steam), press the button to temporarily silence the alarm. The alarm will automatically reset after a few minutes if the smoke clears.

Figure 4: The Test-Hush button for operation and silencing.
- Low Battery Chirp: The smoke detector will emit a regular chirp sound when the 9-volt battery needs to be replaced.
Maintenance
Regular maintenance ensures the optimal performance and longevity of your smoke detector:
- Weekly Testing: It is recommended to test your smoke alarm weekly by pressing the Test-Hush button. This verifies that the alarm is functioning correctly.
- Battery Replacement: Replace the 9-volt battery immediately when the unit begins to chirp. This indicates a low battery. Always use a fresh 9-volt alkaline battery.
- Cleaning: Periodically clean the exterior of the smoke detector with a soft, damp cloth. Do not use cleaning sprays or solvents. Ensure the openings are free from dust and debris to maintain proper smoke detection.
Troubleshooting
If your Kidde i9040 smoke detector is not functioning as expected, refer to the following common issues and solutions:
| Problem | Possible Cause | Solution |
|---|---|---|
| Alarm chirps periodically | Low battery | Replace the 9-volt battery. |
| Nuisance alarms (false alarms) | Cooking fumes, steam, high humidity, dust | Press the Test-Hush button to silence. Ventilate the area. Clean the smoke detector. |
| Alarm does not sound during test | Dead or improperly installed battery, unit malfunction | Check battery installation. Replace battery. If issue persists, the unit may need replacement. |
| Red LED not flashing | Unit not receiving power or malfunction | Ensure battery is correctly installed. Test the unit. If no response, replace the unit. |
For more detailed troubleshooting, please refer to the official Troubleshooting Guide (PDF) or the User Guide (PDF).
Specifications
Detailed specifications for the Kidde Fire Sentry Smoke Detector (Model i9040):
| Feature | Detail |
|---|---|
| Brand | Kidde |
| Model Number | i9040 |
| Style | Battery Powered Smoke Detector |
| Power Source | 9V Battery Powered |
| Color | White |
| Product Dimensions | 4"D x 4"W x 1.45"H |
| Item Weight | 4.2 ounces (120 Grams) |
| Alarm Sound Level | 85-decibel |
| Sensor Type | Ionization |
| Operating Humidity | Up to 85% relative humidity, non-condensing |
| Upper Temperature Rating | 38 Degrees Celsius |
| Certification | UL Listed |
| UPC | 047871260560 |

Figure 5: Compact dimensions of the Kidde i9040 smoke detector.
Warranty and Support
The Kidde Fire Sentry Smoke Detector (Model i9040) comes with a 3-year limited manufacturer's warranty on the alarm unit itself. This warranty covers defects in materials and workmanship from the date of purchase. Please note that the warranty does not cover battery performance.
For further assistance, technical support, or warranty claims, please refer to the official User Manual (PDF) or contact Kidde customer service directly.





