Use of Mass Gas Flow Sensor in Air Sampler

Air sampler is an important instrument for collecting gas, aerosol, and particles samples in the atmosphere ensuring compliance and effective environmental monitoring. It is essential for fixed-point continuous sampling of hazardous gas such as CO, CO2, H2S, NO, O2 and particles such as metal dust in the workplaces of pharmaceutical manufacturing and industrial labs; it is also suitable for routine monitoring and emergency monitoring of ambient air, public health and verifying sources of contamination, prepared media and validation processes in order to meet compliance.

There are passive type air sampler working based on diffused air sampling, and active type based on air pumping collection; fixed constant sampler and portable small type suiting different applications. Verifying the using occasions and detection targets is very important to choose the right air samplers and monitoring devices.

For active air sampler, it has air flow control device to ensure a constant stable flow rate, filter works to get rid of foreign matters and particles to get the target gas sample even in a very low concentration. It helps to verify the contamination sources, recognize the transmission of pollutants, and impact on environmental health.

Air samplers play an important role in scientific research, environmental monitoring, air quality assessment, and industrial emission control. Its data can be used to formulate environmental policies, improve urban planning and management, and assess the potential impact of industrial activities on the environment. With the accurate and comprehensive information, we can better understand and solve air quality-related problems. In addition, the sampler can also be used to detect combustible gases, such as CH4 methane and C3H8 propane, to ensure the gas safety of industries, transportation and construction.

In Chinese industrial standard of “Air Sampler JJG956-2000”, the performance is specified as:

• Flow rate tollerance <±5%
• Flow repeatability <2%
• Flow stability: flow change ≤5% (constant temperature and flow type in 8hrs)
• Timing tolerance ≤±0.2%

These performance of air sampler are decided by the flow control meter integrated with gas flow sensor as the core component to detect and monitor the gas mass flow rate. The thermal mass gas flow sensor is a type of sensor based on the principle of heat transfer, which uses the thermal principle of MEMS to monitor the mass flow of gas in the pipeline. The flow chip is composed of two thermocouple elements or temperature sensors and a heating element. The temperature sensors are symmetrically distributed upstream and downstream of the heating element. The measurement principle of thermal mass flow sensors relies on the heat transfer between the sensor’s heater and the flowing medium.

Wide Range of Applications of Thermal Mass Gas Flow Sensors

The thermal gas flow sensor uses a relatively simple structure to accurately measure the mass flow of gas. It has the advantages of simple structure, very small pressure loss, and wide measurement range. It is widely used in industrial process control, medical equipment, portable instruments, and environmental monitoring equipment.

The gas flow sensor independently developed by Winsen was successfully launched in 2012 and obtained industrial patents. Winsen also participated in the drafting of the industry standard "JB/T 13111-2017 Thermal Mass Flow Sensor".

FR08-H0A is a MEMS thermal mass gas flow sensor from winsen is an excellent choice for air sampling device.

WPAK63 Diffused silicon pressure sensor

• Modular design
• New generation of MEMS sensor chip
• Extremely low starting flow
• High precision, excellent measurement repeatability
• Widely suitable for gas flow detection in the fields of industrial process control, air sampling and environmental monitoring.