Inspection Specification for Online Temperature and Humidity Detector
1、 Purpose of Inspection
Ensure the accuracy and reliability of measurement data from online temperature and humidity detectors, meet environmental monitoring requirements, provide effective data support for production, storage, scientific research and other scenarios, and ensure long-term stable operation of equipment.
2、 Scope of application
Suitable for all online temperature and humidity detectors, including but not limited to:
Industrial environmental monitoring equipment (such as workshops, warehouses)
Agricultural greenhouse monitoring system
Cleanroom monitoring equipment for the pharmaceutical and food industries
Temperature and humidity recorders for cultural relics protection sites such as museums and archives
3、 Testing conditions
Environmental Requirements
Temperature range: 15 ℃~35 ℃ (covering conventional usage scenarios)
Humidity range: 30% RH~70% RH (to avoid extreme humidity affecting sensor performance)
Pressure: Standard atmospheric pressure (86kPa~106kPa)
Avoid strong electromagnetic interference, vibration, or corrosive gas environments.
Equipment Requirements
Standard source:
Temperature standard source: accuracy ± 0.1 ℃, stability ≤ 0.05 ℃/h (such as high-precision constant temperature bath).
Humidity standard source: accuracy ± 1.5% RH, stability ≤ 0.5% RH/h (such as saturated salt solution generator or precision dew point meter).
Auxiliary tools:
Multi channel data logger (used to synchronously collect data from standard sources and the tested equipment).
Insulation resistance tester (used to test the insulation performance of equipment).
Calibration software (supporting data export and analysis).
4、 Inspection items and methods
1. Appearance and structural inspection
Inspection content:
The equipment casing is undamaged or deformed, and the identification is clear (model, number, calibration date).
The sensor probe is free from contamination and corrosion, and the connecting cables are intact.
The display screen or interface function is normal (such as touch screen response, data transmission indicator light).
Judgment criteria: Complies with equipment design specifications and has no defects that affect use.
2. Insulation resistance test
Test method:
Use a 500V insulation resistance tester to measure the insulation resistance between the power input terminal and the casing of the equipment.
Judgment criteria: Insulation resistance ≥ 20M Ω (in accordance with the safety requirements of GB4793.1-2007).
3. Verification of indication error
Temperature inspection:
Inspection points: 0 ℃, 25 ℃, 50 ℃ (covering low temperature, normal temperature, and high temperature ranges).
Method:
Place the tested equipment in the same environment as the standard temperature source and stabilize for 30 minutes.
Record the standard source indication and the displayed value of the tested equipment, repeat 3 times, and take the average value.
Judgment criteria:
Allowable error: ± 0.5 ℃ (high-precision equipment) or ± 1.0 ℃ (ordinary equipment).
Example: The standard source is 25.0 ℃, and the tested equipment displays 24.8 ℃~25.2 ℃ as qualified.
Humidity inspection:
Inspection points: 30% RH, 50% RH, 80% RH (covering low humidity, medium humidity, and high humidity ranges).
Method:
Use a saturated salt solution generator or a precision dew point meter to generate a standard humidity environment.
After stabilizing for 1 hour, record the data and repeat 3 times to take the average.
Judgment criteria:
Allowable error: ± 3% RH (high-precision equipment) or ± 5% RH (ordinary equipment).
Example: The standard source has a relative humidity of 50.0%, and the tested equipment displays 47.0% RH~53.0% RH as qualified.
4. Repetitive testing
Method:
Measure continuously 6 times at 25 ℃ and 50% RH, and calculate the standard deviation.
Judgment criteria:
Temperature repeatability ≤ 0.2 ℃.
Humidity repeatability ≤ 1.0% RH.
5. Response time verification
Method:
Quickly change the standard source temperature and humidity (such as from 20 ℃ to 30 ℃), and record the time required for the displayed value of the tested equipment to reach a stable value of 90%.
Judgment criteria:
Temperature response time ≤ 15 seconds.
Humidity response time ≤ 30 seconds (may be prolonged in high humidity environments).
6. Data transmission verification
Method:
Transfer data to cloud or local servers through interfaces such as 4G/WiFi/RS485 to check data integrity and real-time performance.
Judgment criteria:
Data loss rate ≤ 0.1%.
Transmission delay ≤ 5 seconds (adjusted according to application scenarios).
5、 Inspection cycle
First inspection: conducted after the equipment installation and debugging are completed.
Periodic inspection:
High precision equipment: inspected every 6 months.
Ordinary equipment: inspected every 12 months.
exceptional case:
Equipment maintenance, replacement of sensors, or relocation of installation locations require re inspection.
Shorten the inspection cycle when using in harsh environments such as high temperature, high humidity, and strong corrosion.
6、 Processing of inspection results
Qualification assessment: All inspection items meet the assessment criteria.
Unqualified handling:
Single item out of tolerance: re inspection after adjustment or repair.
Multiple out of tolerance or irreparable: Stop using and scrap.
Record and report:
Fill out the "Online Temperature and Humidity Detector Inspection Record Form", including equipment information, inspection data, conclusions, and handling suggestions.
The inspection report must be reviewed by an authorized signatory and kept for at least 5 years.
7、 Precautions
Before inspection, ensure that the equipment has been preheated to a stable state (usually for more than 30 minutes).
Avoid touching the sensor probe during the inspection process to prevent human interference.
After inspection, restore the equipment to its original working state and record the environmental parameters.
Regularly perform traceability calibration on standard sources to ensure their accuracy.