Skip to content

Calibrate a drop counter

Improve the accuracy of a drop counter, such as the Wireless Drop Counter (PS-3214) or the PASPORT High Accuracy Drop Counter (PS-2117), by calibrating the sensor.

This calibration procedure will require the use of a Drop Dispenser. The materials for assembling this device are provided with the Wireless Drop Counter and the PASPORT High Accuracy Drop Counter. If you do not have these materials, you can order a Drop Dispenser (PS-6935) separately from PASCO. For instructions on assembling the Drop Dispenser, see the manual for your chosen drop counter.

Setup

Before calibrating the drop counter in SPARKvue, follow these setup procedures:

  1. Assemble the Drop Dispenser, then mount the Dispenser to a support rod.
  2. Fill the syringe with titrant. Place a beaker under the Drop Dispenser to catch the titrant as it falls.
  3. Open both stopcock valves, then adjust the valve on the bottom stopcock so that the drops fall at a rate of about 1 drop per second. Once this rate is achieved, close the top valve. Discard the titrant in the beaker as directed by your instructor.
  4. Mount the drop counter to the same support rod as the Drop Dispenser, between the Dispenser and the base. Align the drop tip with the rectangular window of the drop counter.
  5. Place a graduated 10 mL cylinder under the drop counter window so it can catch drops from the drop tip and give you a measure of the volume.

Calibration

  1. Connect the drop counter to SPARKvue.
  2. In the Select Measurements for Templates column, check the box next to Fluid Volume.
  3. Select a template from the Templates column to enter the Experiment Screen.

  4. Click the Live Data Bar for Fluid Volume in the bottom left of the Experiment Screen and select Calibrate measurement.

    Live Data Bar for Fluid Volume

  5. In the Calibrate Sensor menu, ensure that the following settings are selected:

    • Select a sensor: [The name of your drop counter]
    • Select a measurement: Fluid Volume (mL)
    • Select a Calibration Type: 1 point (Adjust Slope Only)

    Sensor Calibration Settings

  6. Click Continue.

  7. Open the top stopcock valve on the Drop Dispenser, allowing titrant to begin dripping into the cylinder. SPARKvue will automatically begin recording the number of drops in the Sensor Value box.
  8. Once about 5 mL of titrant has been collected in the cylinder, quickly close the top stopcock.

  9. Carefully measure the exact value of titrant in the graduated cylinder. Enter this value, in mL, into the Standard Value box, then click Set Calibration.

    Enter the Standard Value

  10. Review your new calibration, then click OK.