Calibrating Sonoflow Sensors

Blood flow sensor with adaptor

Equipment Needed:

  • iWorx Recorder
  • Peristaltic Pump
  • SonoFlow Sensor with tubing that fills the sensor area
  • A-Sonotec adapter
  • Graduated flask or cylinder
  • Stopwatch.

Setup

  • Place the tubing into the SonoFlow sensor. If the size of this tubing is different than the peristaltic pump tubing, use an adapter
  • Plug the A-Sonotec adapter into the SonoFlow sensor
  • Connect the 12V power supply to the A-Sonotec
  • Connect a BNC cable from the A-Sonotec to the BNC input on the iWorx recorder
  • Turn on the A-Sonotec adapter
  • Turn on the iWorx Recorder and Start LabScribe
  • Enable the channel that the flow sensor is connected to
  • Set the sampling speed to 10 samples/second
  • Setup the tubing so that the pump can draw fluid from a reservoir and then push the fluid through the flow sensor into the graduated flask

Procedure

To calibrate the flow sensor you need 2 flow speeds that are around the expected flow ranges that you expect to measure, For example if you have the SNF-55-160 sensor, then the max flow rate is 18000ml/min. You should calibrate the flow sensor between 2000ml/min and 15000ml/min. Make sure that the pump is capable of these flow rates. As an example:

  • LowCalFlowRate = 2000 ml/min
  • HighCalFlowRate = 15000 ml/min

 

In 1 minute the pump will output 2 Liters at the low flow cal (2000ml/min) rate and 15 Liters at the high flow cal rate (15000 ml/min). Since you are measuring time, you will want to measure a long enough time to make sure that the error is minimized. If you use a 5000ml flask, you can fill the flask up to the 2000 ml/min mark for the low flow cal test, which will take 1 minute. Then you can fill it to the 5000ml mark for the high flow cal which will take about 20 seconds.

For our case:

  • LowCalFlowVolume = 2000 ml
  • HighCalFlowVolume= 5000 ml

Measuring the Low Flow Rate

  • Set the pump to output approximately the LowFlowCal flow rate.
  • Start Recording in LabScribe by clicking Record
  • Place a mark in LabScribe “Zero flow”, this is your zero flow value. Type ‘Zero Flow’ in the mark box and click Enter
  • Wait 5 seconds
  • Turn on the pump at the LowFlowCal speed. The signal in the flow channel should increase, and then flatten out
  • Place a mark in LabScribe “LowFlowCal”. Type ‘Low Flow Cal’ in the mark box and click “Enter”
  • When the amount of fluid in the flask reaches the LowCalFlowVolume (2000 ml per the example), turn off the pump
  • This will cause the flow rate channel to drop back to the zero flow value
  • Stop recording
labscribe - Sonoflow cal
  • Using the 2 cursor mode, measure the time that the pump was on. If T is the time between cursors, you can calculate the average flow rate as:
    • ActualLowFlow = LowCalFlowVolume/(Time in minutes)
    • Using the Cursors measure the mean voltage between the cursors: MeanLowValue

Measuring the High Flow Rate

  • Set the pump to output about HighFlowCal flow rate.
  • Start Recording in LabScribe
  • Turn on the pump at the HighFlowCal speed, The signal in the flow channel should increase, and then flatten out
  • Place a mark in LabScribe “HighFlowCal”
  • When the amount of fluid in the flask reaches the HighCalFlowVolume (5000 ml per the example), turn off the pump
  • This will cause the flow rate channel to drop back to the zero flow value.
  • Stop recording
  • Using the 2 cursor mode, measure the time that the pump was on. If T is the time between cursors, you can calculate the average flow rate as:
    • ActualHighFlow = HighCalFlowVolume/(Time in minutes)
    • Using the Cursors measure the mean voltage between the cursors: MeanHighValue

Calibrate the Sensor

  • Zoom out so that you can see all the data
  • Right-Click on the channel and choose Units→Advanced
  • Place the first 2 cursors in the region with the Low Flow Rate
  • Place the last 2 cursors in the region with the High Flow Rate
  • The left 2 values are filled by LabScribe based on the mean voltage between the cursors.
  • Set the right 2 values (do not change the left values)
    • Set Mean Value Between left 2 Cursors xxx => ActualLowFlow
    • Set Mean Value Between right 2 Cursors xxx => ActualHighFlow
  • Set Units to ml/min
  • Click OK
Updated on May 20, 2024

Design Your System

Choose the parameters you want to Measure

ECG/EKG
EMG : Number of Channels
Invasive BP : Number of Channels
Non-Invasive BP : Number of Channels
Flow : Number of Channels
Temperature: Number of Channels
Force: Number of Channels
Stimulation: Describe the type

Recover Password

We will contact you with your login info. 

Newsletter Signup