PendoTECH NFF, TFF Technical Notes

Technical Note

Technical Note: PendoTECH Process Control Systems: Pump Calibration
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Page 1 of 5

PendoTECH Process Control Systems: Pump
Calibration

1. Introduction

The PendoTECH Filter Screening System (NFF) and TFF Process (TFF) allow users to automatically
control flowrates throughout the duration of an experiment or process. Any pump capable of accepting a
remote-control signal can be interfaced with PendoTECH control systems. PendoTECH systems control
pumps by sending an analog signal which is proportional to the flowrate entered by the user on the
system’s graphical user interface (GUI). The analog output is scaled linearly from the pumps minimum
flowrate to its calculated maximum flowrate. The following note describes the process of configuring a
pump with its nominal flow values and making any necessary adjustments to compensate for the inherent
inefficiencies associated with pump technology.

2. Connecting Pumps
a. PendoTECH NFF System

The PendoTECH NFF system is capable of
independently controlling four pumps simultaneously. A
custom cable is included with purchase of the system that
must be specified to match the manufacturer of the pump
to be used with the system, i.e. Masterflex or Watson­Marlow. The four pumps must also be of identical make
and model in order to be used simultaneously. The use of
an adapter cable is available, upon request, if there is a
need to use a pump of different make and model. An
example of a Masterflex pump cable is shown at right and
the pump cable input is called out in the figure below.

Figure 2.1 Back Panel of NFF Control System

b. PendoTECH TFF System

The PendoTECH TFF system can control up to three pumps simultaneously, specifically a main
circulation pump, a diafiltration pump, and a Filtrate/Permeate pump. Unlike the NFF system, the
pumps being used on the TFF system do not need to be of the same make and model. However, it
is important to note that the connection cable between the control system and pump will vary
between different model pumps The pump inputs for the TFF system are called out below.

Note - Only one of the following inputs will be used: Circulation Pump/Circ Pump Alternate

Technical Note

Technical Note: PendoTECH Process Control Systems: Pump Calibration
Revision 0
Page 2 of 5

Figure 2.2 Back Panel of TFF Control System

3. Calibrating Pumps

There are two primary parameters that determine the performance of a particular pump; the maximum
rotations per minute (RPM) of the pumps drive and the amount of liquid that is moved per revolution. The
first parameter is labeled in PendoTECH control systems as Max RPM and the second is labeled as
mL/rotation. These parameters must be input on the “Maintenance View” tab of the control system
software each time a new pump is connected to the system. Once the pump calibration parameters are input
they will be saved to the internal memory of the control system. The parameters are also stored within the
PC program and re-sent to the control system each time the PC software is opened. This is done to confirm
the correct settings are stored in the control system.

The following screenshot from the NFF control system software shows where the max RPM and mL/rot
values are entered. The control system has a drop-down menu that allows the user to select from a list of
standard pump offerings and will populate the nominal performance values for each pump across all four
trains. The user can also select “Custom Settings” if their pump is not listed or if they want to tweak the
nominal settings for more accurate flow control. Refer to section 4 for the process of verifying the
calibration of each pump.

Figure 3.1 NFF GUI "Maintenance View" Tab

Calibrating pumps on the TFF Process Control System software is done in a similar manner. The
calibration parameters are entered on the “Maintenance View” tab however, there is no drop-down pump
selector. Users normally connect different models of pumps to serve as the circulation pump and
diafiltration feed pump in order to achieve optimal flows. Therefore, each pump calibration must be input
separately into the fields noted below. Selection guides available from PendoTECH for popular peristaltic
pump models that provide this information based on tube size.