Air box product specification
Product Name: intelligent air box model:SD0327
function:Detection of indoor air quality, formaldehyde, VOC gas,
CO2, temperature, humidity has a certain detection and reference. 5
values are displayed in the graffiti app and can be linked with
other graffiti smart home devices(Note: data are for reference
only, non professional testing instruments)
Appearance color: white
Material: ABS
Certification: CE / RoHS
Packing list: air box bare metal machine *1, color box *1,
instruction manual *1, clip *1
size:
Color box size 9.5 * 9.5 * 4cm
The overall weight of the product is 95g
Bare weight 58G
Outer carton size 53 * 29 * 37cm
Weight of outer box 750g
Packing quantity 100PCS
Parameter table:
| Product parameter table |
| parameter | minimum value | Maximum | unit |
| working temperature | -20 | 85 | .C |
| Working voltage (rated) | 4.8 | 12 | V |
| Working current | 10 | 496 | ma |
| size | Diameter 90 (round) | Height 35 | mm |
| Power supply mode | USB 5V/1A |
| Communication protocol | WIFI/zigbee |
| colour | white |
| weight | 58g |
| Shell material | ABS |
| Detection range (formaldehyde) | 0 | 10.00 | mg/m3 |
| Detection range (VOC) | 0 | 99.9 | ppm |
| Detection range (CO2) | 0 | 1000 | ppm |
| Detection range (temperature) | 0 | 60 | .C |
| Detection range (humidity) | 0 | 95 | % |
Two detection modules are built in the air box
Air quality semiconductor detection module * 1
Temperature and humidity detection module * 1
1,Air quality detection module:
MEMS VOC sensor is used as a module to detect VOC in air. UART
communication data output, according to VOC data calculation and
equivalent formaldehyde, CO2 output. It has many advantages, such
as small size, low power consumption, high sensitivity and fast
response.
Detection gas organic volatile gas: ammonia, hydrogen, alcohol,
carbon monoxide, methane, propane, glycine, styrene, propylene
glycol, phenol, toluene, ethylbenzene, xylene, formaldehyde, etc.
Life smoke: cigarette, wood, paper burning smoke, cooking fume and
other life odor: life garbage, rotten odor, etc.
Detection concentration:
Cigarette smoke 0.5-5ppm
Alcohol 0.5-100ppm
Hydrogen 1-30ppm
Ammonia 0.8-30ppm
Hydrogen sulfide 0.1-3ppm
Toluene 1-20ppm
The preheating time is 5 seconds to 3 minutes
Response time ≤ 3 seconds
Recovery time ≤ 10 seconds
Working temperature - 20 ℃～ 50 ℃
Working humidity ≤ 95% RH
Storage temperature - 50 ℃～ 60 ℃
Storage humidity ≤ 60% RH
Sensitivity 0.1ppm alcohol
stability
Adaptive ambient temperature and humidity correction
Physical interface
Embedded welding / pin connection
Output data baud rate UART (baud rate 9600bps)
Input voltage 3 ~ 5V DC
Typical value of working current 20mA (5V input)
Standby current < 250ua (5V input)
The service life is more than 5 years
Note: when not in use for a long time or the geographical
environment changes, please preheat in clean air for 5-10 minutes,
and the module will automatically adjust to the best performance.
The start-up measurement after each power-off or sleep needs to
warm up for 5 seconds to 3 minutes. The module automatic
equalization algorithm will dynamically adjust the warm-up time.
1. The sensor has different sensitivities to different gases, and
the module sensitivity only provides reference for alcohol.
2. Input voltage range 3 ~ 5V, wide voltage range, ripple
requirement < 50mV
Working principle of air quality detection module
The module detects the polluted gas in the air by measuring the
sensor, temperature and humidity
Signal processing and output of pollution data to achieve the
detection function of air quality.
●Preheating process
Module power on preheating stable stage, this stage sensor needs to
be heated to a stable state, this time depends on the environment
The lower the temperature is, the longer the preheating time is.
The module is set to 3 minutes, during which the module will
dynamically calculate the preheating time, and the preheating
process can be completed in 5 seconds at least, so as to reduce the
cost of battery powered products
Power consumption. Although the module shortens the warm-up time,
the module will sacrifice sensitivity at this moment
The module preheating time should be extended as far as possible
●Normal measurement
After the module preheating is completed, the module starts to work
normally, and collects sensor data continuously, and then keeps it
clean with the saved one
The data of clean air are calculated to calculate the environmental
pollution value or pollution level.
●Automatic calibration of clean air standard
In order to maintain the high sensitivity of the module and be
affected by the sensor drift, the module will automatically update
according to the algorithm
The clean air reference value is stored in the memory.
●Saturation correction
Under the condition of air pollution, if the air is filtered
through the filter device through the equipment. Air pollution
However, the odor can be filtered through the filter, but the
organic volatile gas in the polluted air can not be filtered, such
as hydrogenation
However, the sensor can still detect relatively high data, which
leads to the inconsistency with the actual feeling of the human
body.
In order to avoid this state, an automatic saturation correction
algorithm is added to the module to change the output value or
level
Don't let the human body feel similar to the actual output
Although saturation correction can bring better correction to a
certain extent, it is very stable in the long term
In a given environment (such as a public toilet with heavy odor),
saturation correction will cause the output data to be clean. all
However, considering the particularity of the environment,
saturation correction algorithm is still introduced.
2,Temperature and humidity detection module
Digital temperature and humidity sensor is a kind of temperature
and humidity composite sensor with calibrated digital signal
output. It uses special digital module acquisition technology and
temperature and humidity sensing technology to ensure that the
product has high reliability and excellent long-term stability.
The sensor consists of a capacitive humidity sensor and an NTC
temperature sensor.
| Supply voltage | DC:3.3-5.5V |
| temperature | -20~+60℃ |
| humidity | 5~95%RH |
| Temperature accuracy | ±2℃ |
| Humidity accuracy | ±5%RH |
| resolving power | T:0.1℃ RH:1%RH |
| Attenuation value (temperature) | <0.1℃/年 |
| Attenuation value (humidity) | <1%RH/年 |
| sensor | Capacitive humidity sensor |
Exceeding the recommended operating range may result in temporary
drift signals up to 3% RH. After returning to normal operating
conditions, the sensor
It will slowly return to the calibration state. To speed up the
recovery process, see recovery processing. Long time under abnormal
working conditions
The use will accelerate the aging process of the product.
Avoid long-term exposure to condensation and dryness, as well as
the following environments.
A. Salt spray;
B. Acidic or oxidizing gases, such as sulfur dioxide, hydrochloric
acid;
Recommended storage environment
Temperature: 10 ~ 40 ℃
Humidity: below 60% RH.
Effects of exposure to chemicals
The sensing layer of capacitive humidity sensor will be interfered
by chemical vapor, and the diffusion of chemical substances in the
sensing layer may lead to the interference
The measured value drifts and the sensitivity decreases. In a pure
environment, pollutants are released slowly. Restoration as
described below
Reprocessing will accelerate this process. High concentration of
chemical pollution will lead to the complete damage of sensor
sensing layer.
Temperature effect
The relative humidity of a gas depends largely on its temperature.
Therefore, when measuring humidity, humidity sensing should be
ensured as far as possible
It works at the same temperature. If the PCB is shared with the
heat releasing electronic components, it should be installed as far
as possible
The sensor is far away from the electronic components and installed
under the heat source, while maintaining good ventilation of the
housing. In order to reduce the heat conduction, the copper coating
of sensor and other parts of printed circuit board should be as
minimum as possible, and a gap should be left between them.
Light effects
Long time exposure to sunlight or strong ultraviolet radiation will
degrade the performance.
Recovery processing
Sensors placed in extreme working conditions or in chemical vapor
can be restored to their original calibration state by the
following procedures
Status. Keep for 2 hours (drying) at 45 ℃ and < 10% RH, and then
keep for more than 5 hours at 20-30 ℃ and > 70% RH.
