Autotutorial for Peristaltic Pumps
How do they work?
Peristaltic pumps are positive displacement pumps utilizing flexible tubes full of liquid and a rotor. Positive displacement means that a set amount of flow rate will be delivered to the system regardless of the pressure on either side. As the rotor turns, it squeezes the flexible tubing, forcing a specific amount of fluid out of the pump.
Pump Speed
The rotor on the peristaltic pump sets the pump speed by how many revolutions per minute that the rotor will turn. We have two types of pumps we currently utilize, one can vary between 1-100 rpm. You may encounter a pump with a capability up to 600 rpm. Check the pump as different ones in Process Controller software require different VIs to operate.
Flexible Tubing Sizes
For each tubing size, different pump speeds will correspond to different flow rates being output by the pump.
The peristaltic tubing sizes are rather arbitrary and are labeled by numbers: 13, 14, 16, 17, and 18 in increasing order of size.
The table below gives you an idea of the flow rates that can be achieved by a peristaltic pump for different tubing sizes.
For 100 rpm pumps
Tubing Number |
13 |
14 |
16 |
17 |
18 |
|---|---|---|---|---|---|
Tubing Size(ID) |
0.8 mm |
1.6 mm |
3 mm |
6.3 mm |
8 mm |
Pump Speed (rpm) |
~2-100 |
~2-100 |
~2-100 |
~2-100 |
~2-100 |
Flow Rate (mL/min) |
0.1-6.0 |
0.3-21.0 |
1.3-80.0 |
4-280 |
6-380 |
For 600 rpm pumps
Tubing Number |
13 |
14 |
16 |
17 |
18 |
|---|---|---|---|---|---|
Tubing Size(ID) |
0.8 mm |
1.6 mm |
3 mm |
6.3 mm |
8 mm |
Pump Speed (rpm) |
~6-100 |
~6-100 |
~6-100 |
~6-100 |
~6-100 |
Flow Rate (mL/min) |
0.36-36.0 |
1.3-130.0 |
4.8-480 |
17-1700 |
23-2300 |
From these charts, you can easily calculate a pump speed given a tubing number and flow rate. At the appropriate tubing number, divide the given flow rate by the maximum flow rate and multiple this quantity by 100. This simple calculation will give you the speed of the pump in rpms given a tubing size and flow rate.
What tubing size and pump speed would you use to acquire a flow rate of 500 mL/min? Keep in mind that you can use more than one pump head...
Pump Calibration
Process Controller has a pump calibration routine available on the configuration tab. The pump calibration ensures that the Stamp Control Box sends the right milliamp current signal to the pump so that it spins at the rpm set by Process Controller. First make sure that you have selected the pump ID number that you want to calibrate. Then make sure that the slope and intercept have the values of 1 and 0 respectively. Always reset these values before doing a calibration. Save those values by clicking on the button to save the Stamp calibration. Close the pump calibration dialog box. Then create a state and a target pump rate of 0.05 (corresponding to 5 rpm for a 100 rpm pump) and a target pump rate of 0.95 (corresponding to a 95 rpm for a 100 rpm pump). Send these pump rate commands to the pump and then use the pump display to see the actual pump rpm. Record those values. For this example assume that the pump rpm was actually 92.8 when the target value was 95 rpm and was 3.2 rpm when the target was 5 rpm. Then return to the pump calibration dialog box and enter the values as shown in the figure. Click on the "calculate the Stamp slope and intercept" button and then click on the button to save the Stamp calibration. After saving the values close the dialog box and confirm that the pump now runs at the target speed set by Process Controller.
