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 Capstone, 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 Capstone.
  2. Select Calibration from the Tools palette.
  3. Make sure that Volume is selected as the measurement to calibrate, then click Next.
  4. From the list of calibration types, make sure that One Standard (1 point slope) is selected, then click Next.

  5. 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 Current Value box.

    Steps for calibrating the drop counter

  6. Once about 5 mL of titrant has been collected in the cylinder, quickly close the top stopcock.

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

  8. Review your new calibration, then click Finish.

    New calibration