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CIP System Troubleshooting Guide 311
The first point of investigation when there is acycling high- and low-level
condition on aqualified CIP circuit is confirmation of the level sensor calibration.
CIP skid level sensors are prone to drift due to the widely varying temperatures
they may be exposed to during the cleaning process. If the level sensor has been
found to be properly calibrated, then aFEinvestigation may be in order; aFEout of
calibration on the high end may overfill the CIP circuit, resulting in circuit
recirculation instability. The troubleshooter must review the process equipment
evaluate the CIP return conditions per previously presented methods to determine
the cause for the temporary process vessel solution hold up.
Recirculation Tank Low Level
When the CIP recirculation Tank reaches low level, common practice is to open the
water supply valve to charge acontrolled volume of water into the CIP circuit to
assist in bringing the CIP skid recirculation tank up to operating level again. If after
the water addition, the tank is not within normal operating range, the water
addition may be repeated a fixed number of times to achieve circuit stability
during recirculation.
An unexpected loss of solution volume can result in alow-level condition at
the CIP unit recirculating tank. This loss may be from aleaky U-Bend at atransfer
panel, apoorly fitted supply hose connection, or an open manual low point drain
valve. The key indicators for an unmonitored solution loss include the CIP skid
recirculation tank is at low level, no rising level is observed the vessel being cleaned,
one or more water additions are required to maintain circuit recirculation, and CIP
Supply flow controland pressure levels may be low during the low-level excursion.
Impact of Water Addition
Awater add action can assist in restoring circuit hydraulic stability. However, the
water addition may have the following negative effects if this action is performed in
excess:
& Reduction of cleaning chemical concentration
& Potential impact on CIP circuit temperature
& If low level is not due to circuit volume loss, may eventually result in a
recirculation tank high-level condition and corrective action, or overflow.
It should be understood that software fixes, i.e., high- and low-level control
actions, are not the ideal approach to balancing CIP circuits. Proper engineering
design can assure proper circuit balance and make these hard to manage, and
troubleshoot, functions unnecessary.
INADEQUATE FINAL RINSE
This section assumes that the piping installation has adhered to American Society of
Mechanical Engineering Bioprocessing Equipment (ASME BPE) recommendations
to keep process/CIP piping dead-legs less than two pipe diameters, and horizontal
in position. It is also assumed that water of proper quality is being supplied for rinse
purposes. The more common causes to be investigated are poorly performing CIP
supply air blow and drain operations before the final rinse, instrument calibration,
poor CIP return flow, and process vessel puddling.