Current position > News detail
『In Check Inspiratory Flow Meter: Calibrating Device Resistance Setting Hubs to Ensure Diagnostic Precision』Related information(v cone flow meter|rotary gas meter|gallon meter|gear meter|metal tube rotameter|glass tube rotameter|nutating disk meter|transit time ultrasonic flow meter|wedge flow meter|pd meters|hydraulic flow meter|ultrasonic water flow meter|water flow meter|air flow meter|magnetic water flow meter|oxygen flow meter|gas flow meter|argon flow meter|air velocity meter|gasoline flow meter|fuel flow meter|ultrasonic water meter|digital water meter|nitrogen flow meter|solid flow meter|Oxygen tank flow meter|digital water flow meter|diesel fuel flow meter|steam flow meter|02 flow meter|compressed air flow meter|oil flow meter|liquid flow meter)
In Check Inspiratory Flow Meter: Calibrating Device Resistance Setting Hubs to Ensure Diagnostic Precision
Quick Answer: Calibrate the resistance setting hubs on an In Check inspiratory flow meter with a clean dry air source and a reference meter. Check each hub at 30, 60, 120, and 180 L/min. If the peak flow reading moves more than 5 percent from target, adjust the hub or replace it before the device goes back into service.
What the Resistance Setting Hubs Do
An In Check inspiratory flow meter does not work like a standard industrial flow meter. It uses a rotating dial with fixed resistance hubs. Each hub contains an orifice and a spring loaded plate. When a patient inhales, air moves through the selected hub. The pressure drop across that hub relates to peak inspiratory flow. If the hub geometry changes, the reading changes.
The hub settings on many devices include 30, 60, 90, 120, 150, 180, 210, and 240 L/min. Some models stop at 180 L/min. Calibration targets each available hub. Most clinics use only four or five settings. That makes the calibration scope manageable.
Calibration Bench Requirements
The bench needs a clean dry air supply. The air should be at 23 °C plus minus 2 °C and 50 percent relative humidity or lower. Log barometric pressure at the start and end of the job. A reference thermal mass flow meter with a range of 0 to 300 L/min covers most In Check hubs. Accuracy should be 0.5 percent of reading or better. The output can be 4 to 20 mA HART or pulse. Silver Automation Instruments supplies thermal mass flow meters for this type of bench.
A pressure transmitter on the reference line is helpful but not mandatory. It confirms that the hub sees the intended inlet pressure. A 0 to 100 kPa range with 0.1 percent accuracy works well. One calibration service house in Kuala Lumpur uses a Silver Instruments thermal mass flow meter and a small air compressor with a 20 liter buffer tank.
Step by Step Check of Each Hub
First inspect the device body. Remove the mouthpiece and check the hub area for dust, fibers, or cracks. Use a dry low pressure air jet at 0.5 bar maximum. Do not use solvents. Some cleaning agents attack the plastic hub seat.
Mount the In Check inspiratory flow meter on the calibration stand. Set the dial to 30 L/min. Start the air flow. Read the reference flow. Record the peak reading. A common acceptance band is 28.5 to 31.5 L/min. If the reading sits outside that band, open the device and check the hub. Repeat at 60, 120, and 180 L/min.
Check hysteresis. Run the dial from low to high. Then run it from high to low. A healthy hub should repeat within 2 L/min. Most mechanical hubs show a small hysteresis. If the difference is greater than 3 L/min, clean the hub again. If the shift remains, replace the hub.
Common Failure Examples from Customer Sites
Most failures are mechanical. A service team in Manila found a 60 L/min hub with a small crack across
Another case came from a biomedical distributor in Johor Bahru. Three devices failed after staff cleaned the hubs with alcohol wipes. The plastic seats softened. The 30 L/min hub became sticky. The flow reading shifted by 7 L/min. Replacement of all contact hubs solved the problem.
Moisture is a slower problem. In a coastal hospital in Penang, humidity reached 85 percent. The metal springs inside the hubs showed light corrosion after 14 months. Calibration drift was only 2 L/min, but the device failed repeatability testing.
Acceptance Limits and Calibration Intervals
For diagnostic use, use an acceptance band of 5 percent of reading or 2 L/min, whichever is larger. For training devices, 10 percent is acceptable. Record as found and as left values for each hub. Put a calibration label on the side of the device. The label should show the date, the technician initials, and the next due date.
Most clinics calibrate once every 12 months. High use clinics that run more than 20 tests per day should calibrate every 6 months. Devices used in dusty environments or stored in humid rooms need shorter intervals.
Reference Flow Meter Selection for Calibration
A reference meter for this job should be fast enough to capture a peak. The response time should be under 100 ms. A thermal mass flow meter with a 0 to 300 L/min range and 4 to 20 mA HART output has enough speed and accuracy. Silver Instruments offers these meters with 1.0 percent accuracy as standard and 0.5 percent as an option.
For a complete calibration setup, send us your flow range in L/min, accuracy target, connection size in DN, and ambient temperature. We can recommend a reference meter or a small calibration skid. Contact Silver Automation Instruments at Tel +86-25-68650347 or WhatsApp +86-25-52155837. WeChat is available at +86 15365082610.
FAQ
Q: How often should an In Check inspiratory flow meter be calibrated?
Every 12 months for normal use. For high use clinics above 20 tests per day, calibrate every 6 months.
Q: What flow points are checked during calibration?
The main points are 30, 60, 90, 120, 150, and 180 L/min. Check both increasing and decreasing flow.
Q: Which reference flow meter works best?
A thermal mass flow meter with a 0 to 300 L/min range and 0.5 percent accuracy works best. A 4 to 20 mA HART output simplifies data logging.
Q: Can a cracked resistance hub be repaired?
No. Replace cracked or worn hubs. Adhesives change the geometry and create larger errors.
Q: What should be included in the calibration record?
Record the as found and as left values for each hub, the reference meter serial number, the date, and the technician name.