In this experiment a stainless steel pump was used with check valves to control liquid flow in and out of the pump. However, pinch valves controlled by the Magma APS control system and in the future, plastic single use pumps, are other options.
Besides controlling the pump cycling, the Magma APS control system has added features for process control and optimization. There may be process operations where it is desirable for a pump to shutdown if excess downsteam pressure builds up. The Magma APS has this feature, and it may be particularly useful when using single use technology with tubing, process bags, and plastic fittings that can rupture and leak if over-pressurized.
Automatic shutdown may be important if handling biohazardous components or valuable intermediate product. Also, as part of the process risk minimization, the system can help offer total process containment (no risk of tubing rupture and leaking from wear).
The control system has an RS-232 input for connection of a scale. An example of how this could be used is for mixing of two liquids. The Magma APS pump can be connected to a process bag to provide mixing, and the bag is placed in a tank on a scale and filled with liquid. A second liquid is added via a tubing pump, and the control system will shut off an addition pump when the weight set point is reached.
The pump offers mixing without the requirement of internal impellers, motors, or an external recirculation loop. This weight control feature can also be used to control vessel volume in a diafiltration or perfusion process if the Magma APS pump is used as the recirculation pump in a crossflow filtration (or TFF) process step.
The control system also has an input for an external pressure sensor (either a stainless steel transducer or disposable sensor). This can be utilized in different applications for process safety, optimization, or testing. A minimum and maximum set-point are entered, and if either of these conditions are met, the control system issues a warning.
Depending where the sensor is used in the process, the high pressure warning may be used to prevent process over-pressurization, and the low pressure warning may be used to monitor filter fouling in a diafiltration or perfusion process.
The control system also has a mode that can perform a pressure hold test or filter integrity test. In the pressure hold test mode, the external pressure sensor and pump air hose are connected to the device to be tested, and the control system internal valves and on-board precision pressure regulator are utilized to conduct the test routine.
The capability to pump against back pressure or a pressurized vessel (such as a bioreactor for additions, etc.) is also important. Pump discharge pressure versus flow data was collected to demonstrate this capability using the Magma APS-50 and water at different vessel pressures.