Why are more CO alarms brands encountering problems with EN50291?
In the European market, EN50291-1:2018 and EN50291-2:2019 are the core market access standard for carbon monoxide alarms. Whether you are a brand owner or importer in the UK, Ireland, Germany, or the Nordic market, your products must meet EN50291 requirements to enter the EU or UK markets, and are usually subject to audits by Kitemark, SGS, TUV, or third-party certification bodies. You may encounter similar issues: interfering with gases causing false alarms, lack of compensation leading to low-temperature failure, significant drift between different sensor batches, and incomplete documentation causing certification delays.
CFS has provided customized services to European CO alarms brands for over 20 years and has found that:
These problems are not due to “bad products,” but rather to an incomplete understanding of the standard or insufficient control over consistency. CFS will provide the brands with a complete guide based on EN50291 standard document, European OEM customer feedback data and past inspection and rectification Experience, including:
What is EN50291？
EN50291-1:2018 and EN50291-2:2019 are the core market access standards for carbon monoxide alarms in the European market. Core requirements include:
- Alarm concentration and timing logic
- Low temperature (-10℃ or -20℃) testing
- High humidity environment testing
- Interference immunity testing
- Sound pressure level ≥85dB
- Battery life and fault indication
There is the difference between EN50291-1 and EN50291-2:
NO. | Items | EN50291-1 | EN50291-2 |
|---|---|---|---|
1 | Usage Scenarios | Residential fixed installation | Campervan/Boat |
2 | Low Temperature Test | -10℃ | -20℃ |
3 | Vibration Test | None | Yes |
CFS does pre-test internal and provides the compliance test in the third lab. OEM must clearly define the sales scenario, otherwise the testing will be sent to the wrong location.
Why is strict compliance essential?
Whether you are a European brand owner, importer, property developer, engineering integrator, or Amazon seller, your products must meet EN50291 requirements to enter the EU or UK markets. There are some reasons, including:
- Regulatory mandate (UK Building Regulations)
- Kitemark/British Standard certification
- Insurance compliance requirements
- Platform sales access (Amazon UK/DE)
If you are found to be non-compliant during a random inspection:
When to prepare compliance test？
Based on over 20 years of design and manufacturing experience, CFS strictly adheres to its new product development process:
What is EN50291 Core Test Requirements？
CFS’s EN products utilize an electrochemical CO sensor. Its working principle is as follows: when CO gas enters the sensor, an oxidation reaction occurs at the sensor’s electrodes, generating a microcurrent. This microcurrent is converted into a corresponding voltage, which is amplified by an operational amplifier. The MCU then calculates the corresponding CO concentration based on the voltage change. It boasts advantages such as high accuracy, a low false-alarm rate, and compliance with mainstream EN requirements. There are five aspects described the EN50291 Core Test Requirements as follows.
1. Alarm Point and Time Logic
Typical Alarm Logic:
NO. | CO ppm | Alert time |
|---|---|---|
1 | 50ppm | No alarm will be triggered (within 60 minutes). |
2 | 100ppm | 10-40 minutes |
3 | 300ppm | <3 minutes |
Risk factors:
- Software algorithm errors
- Sensor drift
- Inaccurate temperature compensation
2. Low Temperature Testing
- -10℃ or -20℃ Environment
- Sensor must maintain sensitivity
Common reasons for failure:
- Reduced electrochemical sensor response
- Slow LCD response
- Decreased battery output
3. High Humidity Test
90%RH Environmental Test
Risks:
- Sensor cross-sensitivity
- False alarms
4. Interfering Gas Detection
- Hydrogen
- Alcohol
- Cleaning Agent Gas
If the algorithm is not perfect, it is very easy to generate false alarms.
What can CFS do for EN50291 Test？
Reliability refers to a product’s ability to perform its intended function under specified conditions and within a specified time. It can be evaluated through metrics such as reliability, failure rate, and mean time between failures (MTBF). CFS assesses CO alarm reliability through tests including Electrical Performance, Environmental Simulation, Product Functional, Mechanical Performance, and Lifetime Reliability.
1. Electrical Performance Testing
- Test product parameters using instruments and equipment to confirm whether the parameters meet the product design specifications.
- Examples: sensitivity, sound intensity (dB), current, low voltage, etc.
2. Environmental Simulation Testing
- Simulate product reliability under different temperature, humidity, and time conditions during transportation, storage, and use, exposing potential defects in advance.
- Examples: high temperature and high humidity, temperature cycling, aging, transportation and storage, etc.
3. Product Functional Testing
- Verify the correctness, completeness, and user-friendliness of product functional design by simulating all or typical operating scenarios of end users.
- Examples: normal operation, software regression testing, power-on/off testing, RF/WIFI connection testing, etc.
4. Mechanical Performance Testing
- Evaluate whether the product and its structural components will suffer mechanical functional damage under mechanical stress or fatigue use.
- Examples: drop testing, impact testing, button lifespan, connector insertion/removal testing.
5. Lifetime Reliability Testing
- Evaluate the failure patterns of the product throughout its entire lifespan and predict its mean time between failures (MTBF) by operating it continuously or cyclically for extended periods under accelerated or normal conditions.
- For example: burn-in test, reliability tests.
How to obtain EN50291 certification?
CFS strictly adheres to procedures for new product development and product reliability management. From prototype design, component selection, firmware design, prototype assembly and testing, packaging design, to pre-certification testing, everything is strictly carried out in accordance with the EN50291 standard to ensure that certification requirements are met as quickly as possible.
Step 1: Design compliance during the design phase
Step 2: Internal Pre-testing
CFS strictly adheres to the requirements of EN50291/UL2034 standards, conducting 37 tests on CO alarms during the trial production phase. These tests primarily include the CO sensitivity test, the hush sensitivity test, the audible test, the low-voltage (Battery) test, the battery polarity reverse test, the high-temperature/high-humidity test, etc. Please see the list.
Step 3: Third-party laboratory test
CFS will use the engineering prototype that has completed the mold-making stage as the certification samples. After completing the main internal tests to ensure the functions are OK, CFS will submit the corresponding number of test samples to BSI, TUV, SGS, or Intertek. The CFS test engineer will communicate with the laboratory weekly to know the testing progress and status and ensure that the testing meets the scheduled time and objectives.
How to control Risk
In European EN50291 or other international standard projects, CO alarms Brands’ biggest risk is not “products not working,” but rather:
The risks typically fall into five categories, as follows:
| Risk list | ||
| No. | Items | Details |
| 1 | Design Risks | • Alarm algorithm not configured according to EN • No temperature compensation • Sensor not aged and screened |
| 2 | Production Risks | • Sensor batch variations • Incomplete 100% gas calibration • Software version discrepancies |
| 3 | Certification Risks | • Incomplete documentation • Non-compliant labels • Missing instruction manuals (multiple languages) |
| 4 | Market Risks | • False Alarm Complaints • No Alarm at Low Temperatures • Unclear Battery Failure Indication |
CFS uses Failure Mode and Effects Analysis (FMEA) and complaint data frequency statistics to classify risks and rank them by Risk Priority Number (RPN).
You also can get more information about design and produce from How to Design Performance-Stable CO Alarms and How to Design Performance-Stable CO Sensors.
No. | Risk Category | Risk Level | Priority Control |
|---|---|---|---|
1 | Alarm Algorithm | Extremely High | First Priority |
2 | Temperature Compensation | High | Mandatory |
3 | 100% Calibration | Extremely High | Mandatory |
4 | Software Version | High | Mandatory |
5 | Instruction Manual | Medium | Cannot be ignored |
Referring to the specific requirements of EN50291 and the internal requirements of CFS, CFS conducts a total of 37 tests to identify potential risks in design prototypes and mass-produced products, and resolves and avoids them during the design phase.
| CFS Internal pre-testing | |||
| NO. | Test items | Apply to the model | Reference standard |
| 1 | CO sensitivity test | All units with CO function | EN50291 6.3.4 |
| 2 | Hush sensitivity test (Alarm silenced test) | All units with CO function | EN50291 5.7 |
| 3 | Audibility test | All units with sound output | EN50291 6.3.16 |
| 4 | Normal operation | All units | CFS |
| 5 | Alarm current(la). Standby current (Is) test | All units | CFS |
| 6 | Low voltage (Battery) test | All units with battery | EN50291 6.3.17 |
| 7 | Low battery voltage performance test | All units with battery | N50291 6.3.18 |
| 8 | Interconnection test | Unit with I/O function | EN50291 6. 3.21 |
| 9 | Battery polarity reverse test | Unit with battery | EN50291 6.3.19 |
| 10 | Rechargeable battery charging and discharging performance | Unit with rechargeable battery | EN50291 5.14.1 |
| 11 | Vibration test(single) | All units with CO function | EN50291 6.3.102.1 |
| 12 | Drop test(single) | All units | EN50291 6.3.15 |
| 13 | Structure interference inspection | All units | CFS |
| 14 | Button life test (1500 times) | All units with button | CFS |
| 15 | Battery carriage or door reliability test (100 times) | All units with new battery carriage or door | CFS |
| 16 | Battery clip deformation test (100 times) & PTT test | Unit with new battery clip structure | CFS |
| 17 | High temperature/high humidity test | All units | EN50291 6.3.23 |
| 18 | Walk-in test | All units | CFS |
| 19 | Abnormal operation test | All units | CFS |
| 20 | Torque force test | All trim plate | CFS |
| 21 | RF connect function | All units with RF function | CFS |
| 22 | RF distance test | All units | CFS |
| 23 | Under voltage /Overvoltage test | All units | EN50291 6.3.10 |
| 24 | PCBA Strain gauge test | All units | CFS |
| 25 | Unpowered storage | All units with CO function | EN50291 6.1.5 |
| 26 | Alarm during warm up time | All units with CO function | EN50291 6.3.5 |
| 27 | Temperature effect | All units with CO function | EN50291 6.3.7 |
| 28 | Humidity effect | All units with CO function | EN50291 6.3.8 |
| 29 | Stability to low humidity test | All CO units | EN50291 6.3.24 |
| 30 | RF compatibility test | All units | CFS |
| 31 | Anti-dismantling function verification | All units | CFS |
| 32 | CO Long term stability | All CO units | EN50291 6.3.14 |
| 33 | CO 5000ppm Test | All EN CO units | EN50291 6.3.6 |
| 34 | CO Air velocity test | All EN CO units | EN50291 6.3.9 |
| 35 | Field-wiring leads | All units | EN50291 6.3.20 |
| 36 | Discharge function test | All 10 Years units | CFS |
| 37 | 100 times PTT Test | All units | CFS |
How to ensure stability and compliance?
CFS® is a leading manufacturer of custom smoke and carbon monoxide alarms and a provider of fire security solutions with over 20 years of experience. From sensor technology to brand implementation, CFS provides end-to-end customization for 200+ global fire security brands. UL, EN, AS, CE certified design capabilities with systematic quality control beyond simple OEM. We have 6 Sigma Management System, 10-Year Battery Algorithm and 100% In-house Sensor Tech.
1. Produce
2. Control
3. Test
4. Maintain Consistency
5. Reduce Complaint
FAQ
Summary
EN50291 compliance is not simply about “passing a test,” but rather:
Truly safe products are not lab samples but remain stable even after mass production. For OEM buyers, the key to choosing a manufacturer is not price, but rather their ability to maintain long-term, stable compliance. If you are planning for the European market, CFS can provide you with:
Enabling your brand to safely enter the European market.
