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return line piping, substantially reducing the quantity of fluid required to fill the
return system. The eductor continuously primes the CIPR pump, moving aroughly
50:50 air–fluid mixture back to the air separation/recirculation tank of the CIP
system, wherethe air disengages fromfluid. The choice between alow-speed and a
high-speed return pump is generally made on need and fluid temperature. If the
discharge head of alow-speed pump is adequate, then alow-speed pump should be
used. If the added discharge head of ahigh-speed pump is advantageous and fluid
temperature inthe cycle will not exceed 608 C, then ahigh-speed pump is agood
option. Beyond 608 C, experience has been that flashing can occur in the high-speed
pump, and thus the low-speed pump is preferred in this circumstance.
Figure 5illustrates atypical biotech facility application where media vessels
(vessels MP-1 to MP-5) located on an upper level combine gravity and top pressure
to feed to bioreactors(vessels BR-1 to BR-3) on ground level. In the lower right-hand
corner of Figure 5isaCIP system with an eductor, which can receive CIPR flow by
gravity and RP-1 combined from the upper media vessels, and eductor-assisted
pumped return fromthe bioreactorsonthe ground level. In aprocess area layout of
this type, the eductor-assisted CIP system might be installed approximately 70 to
100 ft horizontally and 30 ft vertically from the far end of the CIP distribution
piping, but requireonly 30 to 40 gal for recirculation through any circuit. The details
of the installation and operation will be further described in asubsequent section.
Top Pressure Return Flow
The use of aslight top pressureadded to the head space of the target process vessel
being CIP cleaned can be used in combination with any of the above return flow
methods when more conventional means need to be supplemented due to poor
hydraulics. Top pressure is often a last-resort retrofit when other attempts to
balance return flow fail. The top pressure should be kept to aminimum (not
more than 10 psi) to avoid apressure surging condition. Ameans to maintain a
“seal volume” in the process tank must be incorporated. If the outlet of the process
tank blows clear, the entire vessel will need to repressurize. For this reason, an
analog control hold-back valve in the CIPR line can be added to always maintain a
low-level volume in the process tank, except on program steps where complete
drainage is required.
CIPS AND CIPR FLOW DISTRIBUTION CONTROL
Lebowitz
As discussed previously for CIP distribution with portable CIP systems, there are
some situations where flexible hose is asuitable means of branching flow, such as
changeover of the outlet discharge configuration of aprocess tank from process to
CIPR mode. This may be acceptable in asmall pilot plant setting, but for large-scale
good manufacturing practice facilities flexible hose allows no chance of automation
to ensurethat acorrect flow path has been established. Also, hoses create acleaning
challenge due to difficulty in keeping track of their use and cleaning, as well as being
adetriment to maintaining proper line pitch and drainability.
The next simplest approach to control connections is the make–break elbow.
In this case, three adjacent lines come in proximity with aplanned geometry so that
a“key piece” or “swing elbow” can connect between different pairs. While make–
break elbows do not allow automated tracking of process connections, they are a
great improvement over hoses with regard to maintaining pitch and drainability.