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CIP Supply/Return Piping Systems

In many processes it is necessary to clean processing and storage vessels during the production period. A number of those vessels may also contain product when the process piping is subsequently cleaned in-place. Therefore, permanently installed CIP supply/return piping became an integral part of the earliest "automated" CIP installations. 

• The 3-A Accepted Practices (Reference) for Permanently Installed Sanitary Product Pipelines and Cleaning Systems require "All connections between the solutions circuit and the product circuit shall be constructed as to positively prevent the commingling of the product and solution during processing"
• Compliance with this requirement is best accomplished via the installation of separate CIP supply/return piping. The "make-break" connections between the product vessels, the process lines, and the CIP supply/return lines generally consist of removable elbows, U-bends, or "goosenecks" (an elbow on a straight length of tubing) physically arranged to prevent improper connections, or simultaneous connection of a tank to product and CIP solution lines.
• In accordance with the 3-A Standards, the CIP supply/return piping requires the same consideration of materials, gasket design and materials, fabrication technique and support as does the product piping. 

Several different CIPS/R Alternatives are shown on this isometric drawing. These may be combined in any manner suitable. 

• The traditional cleaning hook-up station (CHS1) and return header shown for tanks T1-3 represents the approach common to dairies, breweries, wineries, and other processes which involve the need to frequently clean one (1) of a large number of storage tanks via separate CIPS/R piping. In this instance, to eliminate the accumulation of undefinable mixtures of water, product and cleaning solutions in the "dead end" of the traditional return header, a supply valve on the CIPS to the CHS is connected via a CIP tie-line to the return header. Programmed control of this valve will enable the return header to be flushed with the appropriate solutions during each step of the CIP program, thereby eliminating any development of product or solutions residues in the return header. 
• An alternative "loop-type" CIPS/R concept is illustrated as the means of providing CIPS/R capability to tanks T4-10 inclusive, in several different manners. The objective of this revised approach is two-fold and includes (a) totally eliminating the possibility of any "dead ends" in that portion of the system in use and (b) providing a uniform supply and return path for each of the tanks in the several groups at various locations within the facility.
• A centrifugal pump installed in the discharge line of T6 would be used for product transfers and CIP return, generally being provided with a variable frequency drive (VFD) for capacity control.
• A permanently installed return pump is shown as the means of returning solution from tanks T8-10, which connect to ports on TP3. For CIPR, the inlet of RP2 would connect to the lower header used as the CIPR header and the tank outlet line would also connect to this header.
• A portable CIP Return Pump RP3 would be used at tanks T4, T5 and T7. This pump would connect via a hose directly to the tank outlet valve (T4-5) or to the port on TP2 for T7, and via another hose to a return port on CHS2 or TP2 as shown on the illustration.

The above referenced illustration depicts centrifugal return pumps used in combination with an eductor assisted CIP system.  Most conventional CIP systems use only the un-assisted return pump.  Gravity or gravity assisted CIPR flow is highly desirable, when possible, via strategic location of the CIP Unit below the circuits to be cleaned 

Uniform Flow-Rates

• Experience has demonstrated that operation and maintenance of a CIP system will be simplified if a uniform approach is applied to all vessels in a given facility or system.
• Select sprays, design and install supply/return piping and pumps and size tank outlets so that all tanks in a given system are cleaned at approximately the same flow-rate and spray supply pressure, or a minimal range of pressure and flow..
• This approach permits the use of relatively uniform pre-rinse and post-rinse volumes as well as drain times, and reduces the variables in the cleaning program to the time/temperature/solution strength combination necessary to remove the soil.
• The volume of water required to rinse a piping circuit is normally found to be 1-1/2 to 2 times the volume contained in that piping.  This may be increased to 4-5 times the volume of the circuit to meet pharmaceutical and biotech final rinse test criteria.