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Air Flow Meter Asthma: Managing Daily Expiratory Target Action Zones
Quick Answer: Silver Instruments supplies thermal mass flow sensors to medical device OEMs that build asthma expiratory flow meters. We calibrate air flow sensors for 0 to 900 L/min ranges with 4-20 mA HART or 0 to 5 V DC outputs. Send us your gas type, flow range in L/min, pressure in bar, and output signal.
What Is a Daily Expiratory Target Action Zone Device?
A peak expiratory flow meter is common in asthma management. The patient blows into the device. The meter reads the maximum flow rate during one forced breath. A doctor uses the personal best value to set three zones. Green zone means 80 to 100 percent of personal best. Yellow zone means 50 to 79 percent. Red zone means below 50 percent. These daily expiratory target action zones guide medication steps.
Where Industrial Flow Meter Suppliers Fit In
Silver Instruments does not sell consumer peak flow meters to patients. We supply the internal gas flow measurement sensors to OEMs in Southeast Asia, Latin America, and the Middle East. These manufacturers assemble respiratory devices and need stable low range air flow sensors. Thermal mass flow meters work well here because they measure mass flow directly and handle low pressure gas streams.
Flow Range and Accuracy Requirements for Asthma Devices
Most adult expiratory flow sensors need a 0 to 900 L/min range. Some paediatric devices use 0 to 400 L/min. Accuracy of 2 to 3 percent full scale is acceptable for many designs. Response time under 50 ms matters for peak detection. We calibrate our thermal mass flow sensors at 200, 400, 600, and 800 L/min on a reference bench. This multi point calibration helps the OEM map green, yellow, and red zones in firmware.
Target Action Zones and Calibration
In practice the green zone starts at 80 percent of personal best peak flow. The yellow zone covers 50 to 79 percent. The red zone starts below 50 percent. The flow sensor must keep linear output across these zones. Our thermal mass flow meters hold plus or minus 1.5 percent repeatability across the 0 to 900 L/min span. We can linearize the 4-20 mA signal to match your zone thresholds. This reduces work for the OEM firmware team.
Recommended Silver Instruments Flow Meter Series
We recommend our thermal mass flow meter series for expiratory flow devices. The sensor body is available in DN15 and DN25. Wetted materials include 316L stainless steel and aluminum with PFA coating. Standard output is 4-20 mA HART. Optional outputs are 0 to 5 V DC and RS485 Modbus. Supply voltage is 24 V DC. Process temperature range is minus 20 to 60 degrees Celsius. The pressure drop stays u
Why Low Pressure Drop Matters in Expiratory Flow Measurement
Here is the thing. A flow sensor placed in the expiratory path adds resistance. If the pressure drop is too high, the patient blows harder just to overcome the meter. That changes the peak flow reading. We keep pressure drop below 0.1 kPa at 600 L/min for most air flow ranges. This matters for asthma devices. It also matters for any respiratory gas measurement where patient effort affects the reading.
A Real OEM Request from Southeast Asia
A respiratory device assembler in Ho Chi Minh City contacted us last year. They needed a flow sensor with a 0 to 800 L/min range, 1.5 percent accuracy, and a 0 to 5 V DC output. They also needed calibration at 200, 400, and 600 L/min. We shipped five samples in 18 days by DHL. The customer then ordered 200 units for their production line. That order took 25 days to complete.
Selecting the Right Air Flow Meter for Asthma Devices
Send us these details. Gas type can be air or an air and oxygen mix. Maximum flow in L/min usually falls between 400 and 900. Operating pressure is often close to atmospheric but state it in bar. Operating temperature in degrees Celsius. Output signal. Connector type and body material. Our engineers will recommend a thermal mass flow meter or a differential pressure type if the flow span is narrow.
FAQ
Can Silver Instruments supply a complete consumer asthma peak flow meter?
No. We supply the internal gas flow sensor to medical device manufacturers. We do not sell direct to patients or pharmacies.
What flow range is typical for asthma expiratory flow meters?
Adult devices commonly use 0 to 900 L/min. Paediatric devices often use 0 to 400 L/min. We can calibrate for other spans.
What output signal do you recommend for respiratory devices?
4-20 mA HART is standard for industrial sensors. Many OEMs request 0 to 5 V DC for battery powered handheld devices. RS485 Modbus is also available.
Do you calibrate flow meters to green, yellow, and red action zones?
Yes. We can linearize the output to match your zone thresholds. Tell us the flow values where each zone starts and ends.
How fast can you ship samples to Southeast Asia or Latin America?
Typical sample lead time is 15 to 20 days after drawing approval. DHL delivery takes 3 to 5 business days. Production orders take 20 to 30 days depending on quantity.
Contact Silver Instruments for air flow meter selection. Tel: +86-25-68650347. WhatsApp: +86-25-52155837. WeChat: +86 15365082610.