Drop Counter
2
012-08470G
Introduction
The Drop Counter measures the number of drops of fluid
that fall through the rectangular opening of the sensor. It is
typically used in conjunction with a pH sensor and other
equipment to perform a titration. Data from the Drop
Counter and other sensors are recorded and displayed in soft-
ware such as SPARKvue, PASCO Capstone, or on a datalog-
ging interface such as the SPARK SLS or Xplorer GLX.
The Drop Counter can be mounted on a support rod and the
support rod can be clamped to a rod stand. The counter is
equipped with three integrated probe holders. The included
Micro Stir Bar fits onto the end of a pH probe or probe of the
same diameter.
Assembling the Drop Dispenser
1.
Remove the plunger from the syringe.
2.
Connect the two stopcocks together and set the valves at
right angles. Connect the stopcocks to the end of the
syringe.
3.
Connect the drop tip to the bottom of the stopcocks.
Calibrating the Drop Counter
The Drop Dispenser has two stopcocks. The top stop cock is
used to regulate flow rate and the bottom stopcock is used to
turn the flow on and off. The bottom stopcock should either
be in the completely open or completely closed position.
The following two methods illustrate the calibration proce-
dure.
Calibration (Generic Process)
1.
Attach the Drop Dispenser (syringe, two stopcocks and
drop tip) to a support rod.
2.
Fill the syringe with titrant.
3.
Open both stopcock valves and adjust the valve on the
top stopcock so that the drops fall at a rate of about 1
drop per second. Close the bottom valve after the rate is
achieved.
4.
Connect the Drop Counter to a PASPORT interface.
5.
Align the drop tip with the opening in the Drop Counter.
Put a graduated 10 mL cylinder under the Drop Counter
opening.
6.
Open the bottom stopcock valve and monitor the num-
ber of drops.
7.
After about 10 mL of titrant is collected in the graduated
cylinder, close the bottom stopcock.
8.
Open the calibration screen in the data acquisition soft-
ware and input the number of drops and the volume.
Calibration Using SPARKvue or SPARK SLS
The drop counter is calibrated, using the SPARK SLS or
SPARKvue Tools to correlate the number of drops counted
to the volume of liquid dispensed from the Drop Dispenser.
1.
Attach the Drop Dispenser (syringe, two stopcocks and
drop tip) to a support rod.
2.
Fill the syringe with titrant.
3.
Open both stopcock valves and adjust the valve on the
top stopcock so that the drops fall at a rate of about 1
drop per second. Close the bottom valve after the rate is
achieved.
4.
Connect the Drop Counter and launch SPARK SLS or
SPARKvue.
5.
Align the drop tip with the opening in the Drop Counter.
Put a graduated 10 mL cylinder under the Drop Counter
opening.
60 mL syringe
with 50 mL of
0.1 M NaOH
150 mL
beaker with
100 mL of
0.005 M HCl
Three-finger
Clamp
Multi
Clamp
Stopcock
Stopcock
Drop Tip
pH Probe
Micro Stir
Bar
Stir Plate
