——Practical experience from carbon monoxide sensors and alarm manufacturing engineering experts
Over the past 20 years of product ODM/OEM and market support, CFS has found that the long-overlooked problem for end-users isn’t sensor accuracy, but that they don’t understand what the alarm is trying to convey.
For brands, product managers, and purchasing managers, mishandling this issue can ultimately lead to:
This blog will give a proven system solution from manufacturing engineering and market feedback.
Confusion: Users cannot understand the alarm’s meanings
A typical problem raised in numerous user feedback reports is:
“The alarm is activated, but I don’t know if it’s a CO alert, a low battery warning, or a device fault.”
Many end users think that the alarm is only a beeping sound and an LED flash. However, the device may be in several states internally from an engineering perspective:
Without clear distinctions, users often misjudge the situation.
How large is the problem?
This problem is far more serious than imagined, according to publicly available industry data and market feedback.
1. Consumer Complaint Rate
Data from the U.S. Consumer Product Safety Commission (CPSC) shows that approximately 28% of inquiries related to CO alarms are about “not understanding the meaning of the alarm.”
In other words, the problem is not a device malfunction, but rather a failure to convey information.
2. User Behavior Survey
In a survey of home users:
63% of users had never read the entire instruction manual for their alarm system.
Therefore, any design that relies on the manual to explain the alarm logic inherently carries a risk.
3. After-Sales Returns
According to after-sales data from multiple brands:
Approximately 35% of returned products were found to be completely normal after testing.
The main reasons for user returns are:
- Mistakenly believing the equipment is malfunctioning
- Unable to understand alarm prompts
Root Cause: Design Thinking Remains at the Engineering Perspective
From a manufacturing perspective, most alarm designs still employ traditional logic:
Engineering Logic: Buzzer → Different Rhythms → Instruction Manual Explanation
However, Users often hear the buzzer in the following situations in reality:
In these situations, users won’t consult the instruction manual.
The essence of the problem is not technology, but insufficient information design.
Solution: Three-Tier Alarm Information System
In actual projects, we recommend that OEM customers adopt a three-tier alarm information structure.
1. Standardized Sound Patterns
The industry currently widely adopts sound logic like that of smoke alarms. This is a Status Sound Pattern based on fire alarm design principles:
This design is from the standard logic of fire alarm systems.
For example, in smoke alarms, based on the photoelectric smoke detection principle:
When smoke enters the smoke chamber, the photosensitive LED captures the scattering signal change, triggering a four-beep alarm mode to prompt the user to evacuate immediately.
Also you check the link to get more information about How They Work?
But there are a few differences between CO alarms.
When the alarm detects CO, the sensor generates a current of 1.0-2.5nA/PPM, causing a decrease in the negative voltage at the sensor terminals and an increase in the operational amplifier’s Vout. After the CO concentration accumulates for a certain period, once the continuously accumulated CO concentration value collected by the MCU reaches the software-set alarm threshold, the CO alarm enters alarm mode.
The UL2034 standard specifies the alarm time requirements for alarms at different CO concentrations.
The EN50291-1 standard specifies the alarm time requirements for alarm devices under different CO concentrations in Table 2.
Smoke alarms detect changes in smoke particles through a photoelectric chamber and convey different status information to the user through sound and light signals.
This “sensing → judgment → sound and light prompt” structure is also the basis of CO alarm design.
2. Visual Status Cueing
While sound cues are effective, they still have limitations.
Therefore, modern products increasingly employ multi-status LED indicator systems. For example:
Red flashing: CO alarm
Yellow flashing: Fault
Green flashing: Normal operation
This design conveys status without requiring the reader to read the instruction manual.
For OEM products, this design is extremely low-cost yet significantly improves the user experience.
3. Information Visualization
For mid-to-high-end products, we recommend adding a digital information layer.
For example: LCD display:
- CO concentration (ppm)
- Battery status
- Fault codes
This design can significantly reduce after-sales inquiries.
For example: If a user sees CO 120 ppm, they can determine that it is an actual CO alarm, not a device malfunction.
Please check the link to get more information about how to design performance stable CO alarms.
Case Study: Changes After an OEM Brand Upgrade
CFS once optimized the product structure for a European brand. Their original product structure:
After-sales issues mainly focused on:
After the upgrade, the following were added:
Results: After-sales inquiries decreased by 49.8%, and the return rate decreased by 34.3%. More importantly, user trust in the product significantly improved.
Recommendations for OEM Product Managers
From a product planning perspective, we recommend:
Don’t focus solely on sensor accuracy. Equally important:
In CO alarm products, a good design should ensure that users can understand the device status within 3 seconds.
Conclusion
“Users not understanding what an alarm means” is not a simple user problem, but a product design problem.
From a manufacturing engineering perspective, the solution is not complex:
This three-layer structure has been thoroughly validated in the smoke alarm and CO alarm industry.
For OEM brands, this not only improves product safety but also significantly reduces after-sales costs and enhances brand professionalism.
In the field of safety products, truly excellent design is never about “making it more complex,” but rather allowing users to immediately understand what the device is saying, even in the most stressful moments.
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