Selecting and installing CIP systems interfaced with cleanrooms
02/01/2008
The successful implementation of a CIP system is determined by cost effectiveness, completion on schedule, and reliable cleaning
By Sally J. Rush, Seiberling Associates, Inc.
Regardless of the type of facility???pharmaceutical, food, beverage, or fine chemical???there are numerous clean-in-place (CIP) questions that are common to every such project. How these questions are answered during conceptual design of a clean process facility can impact the success of the installation, with “success” determined as having a cost-effective installation, completed on schedule, that results in reliable equipment cleaning. Some of the common concerns are noted here, along with project considerations that must be addressed to ensure success.
Single-pass vs. recirculated CIP cleaning units
A single-pass CIP unit generates the flush, wash, and rinse solutions at the required concentration, temperature, and flow rate and delivers these solutions to the equipment to be cleaned. Figure 1 shows that after passing through the process equipment, the spent CIP solution is discharged to waste locally at the equipment or enters the CIP return piping to be discharged to waste at the unit. A recirculated CIP unit (Fig. 2) generates those same solutions under the required critical control conditions, and performs the same duty of solution supply to the cleaning circuit. When using a recirculating CIP unit, the rinse phase solutions are returned to the unit for controlled and monitored discharge to drain. During the chemical wash phases, sufficient cleaning solution is made up to fill the circuit, meeting the critical control parameters, and recirculated through the CIP unit to be resupplied to the cleaning circuit. The nature of a recirculating CIP unit ensures reduced chemical, water, and energy usage, and the unit generates less waste for handling.
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One must consider the project-specific aspects to pursue the selection of either a single-pass or recirculating CIP unit, such as the nature of the soil to be removed.
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If the facility has equipment designed to be cleaned in place, and the soil is easily solubilized, a single-pass CIP unit can be implemented. An example in the pharmaceutical world is a buffer prep and hold operation; single-pass cleaning is also common in juice processing in the food industry.
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If the process includes a fat component, an insoluble protein, or a tenacious mineral, the decision will be driven toward recirculated cleaning due to the need for an extended CIP chemical wash program with higher chemical concentrations, longer wash durations, and perhaps a higher cleaning temperature required to remove the soil. Under these conditions, single-pass CIP is a less feasible option due to the increased burden on utilities and substantially increased chemical concentration and waste handling costs.
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There are special concerns, however, if process soil includes an insoluble particulate. For example, a CIP cleanable aseptic barrier filling operation or freeze dryer that involves vial handling may include broken vials as part of the CIP cleaning load. These glass particulates can easily be suspended in solution and enter the CIP system, spreading to other operations cleaned by the CIP unit. Where there are insoluble particulates that cannot be easily removed from the CIP return stream, the decision swings to single-pass cleaning to ensure particulates do not recirculate throughout the facility.
Impact on utilities and waste handling capacities
The utility issue was briefly considered in the previous section, noting that single-pass cleaning has a greater impact on the utility capacity required to achieve cleaning. However, to properly evaluate the impact of the decision, the number and type of CIP circuits to be cleaned need to be considered along with the anticipated cleaning schedule.
First, the CIP program must be defined in a preliminary manner, identifying the number of rinse and chemical wash phases, with phase durations estimated based on preliminary cleaning trials on a specific soil. The knowledge, along with the CIP flow rate for each circuit, will complete the picture and allow the water, energy, and chemical consumption to be estimated. Estimates should be made for (a) each CIP circuit, (b) worst-case cleaning load for a 24-hour time period, and (c) the maximum instantaneous demand. These data also provide an accurate picture of the CIP waste generated under the varying conditions.
When creating chemical cleaning solutions in single-pass mode, the chemical and energy costs increase to blend a cleaning solution to the specified concentration and wash temperature. If the CIP solution must be heated or cooled to the CIP set point supply temperature, the heat exchange capacity is increased, along with the cost and size of the equipment needed to accomplish the task. These factors must be identified during conceptual design because they can impact the equipment layout, budgetary estimates, and chemical feed system design.
An analysis of single-pass vs. recirculated cleaning may reveal a five- to ten-fold difference in water, chemical, and energy consumption. These numbers should be evaluated during conceptual design and reviewed again during detail design to ensure adequate utility and waste handling capacity and a chemical feed system that suits the cleaning conditions.
Impact of CIP program definition on project budget
The previous section noted a five- to ten-fold difference in water usage and waste handling capacity if single-pass cleaning is used in lieu of recirculated cleaning. If reverse osmosis, deionized water, or water for injection is selected as the cleaning water, there may be an increase in the number of filtration systems or stills required to create the volume needed to accomplish single-pass cleaning. If the CIP program is not identified until detail design or later, the facility equipment set is often insufficient to generate the solutions required to accomplish cleaning. If not considered during conceptual design, the floor plan or budget may not allow for the expansion to achieve effective cleaning operations.
Similarly, single rinse duration of 5 minutes vs. 10 minutes may seem insignificant during the design phase, but when applied three to four times per circuit, 10 to 20 times per day, it may result in a grossly undersized water supply and waste handling system.
Impact of process equipment cleanability
If the process equipment, piping, and devices have been specified and installed for in-place cleanability, either recirculated or single-pass CIP can be applied. If the equipment is not designed to be cleanable and the facility is multi-product, it may not be desirable to use a recirculated CIP unit because soil may reside in the equipment after the CIP program has concluded, and cross-contamination of dissimilar products may occur through the unit. If the tenacious nature of the soil and utility limitations drives the decision to recirculated cleaning, manual cleaning must follow the CIP operations. Additionally, the unit must be cleaned to reduce the chance for cross-contamination. In these instances, it is helpful to have a CIP circuit simply involving the CIP supply and return piping to automatically clean the CIP system, reducing the chance for cross-contamination.
Facility layout impact on unit selection and performance
The CIP unit should be located close to water and chemical supplies, as well as waste discharge destinations to minimize installation and operating costs. The optimal installation for most CIP units is illustrated in Figs. 3 and 4, with the unit located on the lowest floor of the process, centrally located under the clean process equipment, taking advantage of gravity for equipment drainability, improving CIP return flow, and reducing drain times. When properly executed, this approach to installation can eliminate CIP return pumps along with pump casing drain valves and drain piping, again reducing installation and automation costs.
If a single-pass or recirculating CIP unit is located on the same floor as the clean process operations, then a CIP return pump will be required. A self-priming CIP return pump, which can pump air-water mixtures, is the best option for efficient CIP return flow when considering same-floor operations.
The only situation in which the CIP unit may be effectively located above equipment to be cleaned is when considering single-pass CIP systems, with cleaning solutions cascading down through the equipment and continuing to drop to a low-level waste handling system. Pumped CIP return flow to upper-level CIP units results in poor drainability and lack of clarity in transitions between chemical wash and rinse phases, usually increasing rinse water volumes and CIP circuit durations.
Integrating the CIP system with cleanroom installations
Using Figs. 3 and 4, we explore two different means of installing a CIP system. The illustrations assume the optimal CIP unit location, physically below the process being cleaned, close to utilities and enhancing gravity flow for CIP drainage. Figure 3 shows the CIP supply piping rising vertically to a mechanical space on the same level as the process operations. The CIP distribution and collection piping enters the mechanical space, and a transfer panel is used to introduce CIP solutions to the cleanroom. The transfer panel is installed through the wall, with any mechanical components on the backside of the panel (e.g., valves, proximity switches, and monitoring instrumentation). This enables the CIP piping to enter the clean space, with all automated devices that require maintenance in the mechanical room.
Figure 4 shows a more automated approach, without manual intervention in the cleanroom to interconnect process and CIP piping. This approach also eliminates the intermediate mechanical room on the process level, with all mechanical space below the process. The CIP supply piping rises vertically to a CIP distribution valve group elevated in the lower mechanical space. The CIP distribution and collection piping enters the cleanroom from below or from a process-level pipe chase. The CIP return route mirrors the supply route with a CIP return valve group elevated above the unit, directing CIP solution back to the unit or waste. The valve groups and piping are designed to ensure cascading flow without piping low points or pockets and may include monitoring devices. These approaches again ensure that all automated devices are located in mechanical space, minimizing cleanroom components.
Process contamination concerns associated with CIP
The obvious concern is ensuring all process soil and residual chemicals have been removed from the process at the conclusion of a CIP operation, which can be confirmed though final rinse sampling and equipment swabs as part of cleaning validation. One less obvious process contamination issue can occur through compromised water or chemical supplies. These concerns can be remedied by quality monitoring of the raw materials, with acceptance criteria set for water and chemical purity. In addition, purified water supplies should be protected from chemical supplies and solutions.
The final contamination concerns relate to the fact that the CIP tanks are vented, though they may not come equipped with 0.2-??m vent filters. The CIP tanks “breathe” mechanical room air as CIP is executed, and that air may contain particulates. When the CIP unit is located in mechanical space, the CIP vent should be equipped with heat traced, 0.2-??m vent filters to prevent particulate contamination through the CIP unit.
Recommendations on how to achieve CIP project success
CIP system considerations should be evaluated as early as possible in the conceptual design phase to identify a few key points:
- Identify the CIP unit along with the CIP program and critical cleaning parameters.
- Prepare an accurate estimate of the utility requirements to support cleaning and clearly communicate it to those planning the facility’s infrastructure.
- Determine the location and means of seamlessly integrating the CIP system and cleanroom process operation.
Early identification of a CIP system “owner” can have a great impact on project success. This individual takes a lead role throughout the project, ensuring CIP concerns are addressed from concept through commissioning, ensuring a smooth transition to manufacturing operations.
Sally J. Rush is vice president at Seiberling Associates, Inc. (www.seiberling.com), an engineering and technical consulting company providing process, CIP, and steam-in-place (SIP) design and control system integration services.