Equipment is cleaned out of place as a whole (i.e., tanks) or as a part disassembled from a larger system. The equipment can be cleaned semiautomatically or manually.
COP applications are divided into two groups:
- Automated, for example, parts washers
- Semiautomated, for example, ultrasonic washers
Semiautomated cleaning is automated cleaning with some level of manual involvement, such as disassembly, relocation, cleaning accessory setup, and placement or staging of equipment. The equipment can vary from large vessels to small parts. In general, larger vessels are cleaned internally using cleaning devices (e.g., spray balls or jet sprayer), and small parts are cleaned using an enclosed cleaning apparatus such as a parts washer or ultrasonic cleaner.
COP Stations
Vessel-type equipment can be cleaned using a COP station. The COP stations clean the internal surfaces of equipment. The external surfaces are usually cleaned manually prior to or following the semiautomated cleaning cycle. It is generally preferred to clean the external surfaces prior to cleaning the internal compartment so that internal surfaces do not get re-contaminated during external cleaning.
The manual involvement is usually limited to connecting supply/drain lines and cleaning devices. The COP station can be stationary or mobile. In some cases, a CIP skid can be dual purpose (i.e., CIP circuit and COP).
The advantage of using a COP station is that it is a relatively automated process. Supply and drain line connections can be easily verified. Proper placement of cleaning devices may also not be a concern (depending on equipment geometric shape and internal configuration). If the precise placement of the cleaning device is critical, it should be addressed (e.g., load pattern) during development, prior to cleaning validation, and routinely after validation.
With proper justification (i.e., documented load pattern), validating a COP station can be similar to validating an automated system (i.e., CIP circuit).
Although the cleaning of the external or non-product contact surfaces does not need to be validated, it should be proceduralized and visual cleanliness should be assessed.
Washers
There are various types of washers, for example, parts washers, cabinet washers, and ultrasonic cleaners. Washers have the advantage that they can clean the internal and external surfaces of equipment; however, there are some clear disadvantages.
The placement and staging of the equipment are crucial. The most important aspect when designing and validating the cleaning procedure is part placement and movement during cleaning. Load patterns need to be consistent using pictures of the loaded washer as a guide. Even if performed properly, the equipment can move during cleaning. Layering or stacking parts should be avoided.
For parts directly connected to a port on a cart or directly from a COP skid, unless there is unusual geometry, the equipment should be evaluated and validated as piping.
The placement of equipment cleaned by individual spindles or in a basket needs to be assessed and proceduralized.
When assessing for cleanliness, testing only the final rinse may not be adequate for validation, as the rinse sample is diluted significantly, creating a false sense of cleanliness. In addition, the rinse sample is a compilation of all of the parts cleaned in the load; any failures could not be correlated to a specific piece of equipment. Parts (i.e., worst case) should be sampled individually (i.e., swab or rinse) for cleaning validation.
Cabinet Washers
Cabinet washers are mainly used to clean large to medium vessels. This type of cleaning is similar to COP station cleaning but usually includes exterior surface cleaning.
The small parts can also be cleaned using cleaning carts, similar to a parts washer. This type of cleaning should be evaluated similar to a washer.
Ultrasonic Cleaners
Ultrasonic cleaners clean using ultrasonic waves. The frequency setting may be fixed or adjustable.
As with washers, part placement and orientation need to be evaluated. During evaluation, the cleaner should be sectioned off into quadrants. Each quadrant needs to be tested to determine the ultrasonic activity, as each quadrant may have a different intensity. The intensity and distribution of the cavitation can be tested using foil strips, kits, or an activity meter. During development and/or validation, the worst-case quadrant can be challenged.
Though ultrasonic cleaners can be very useful in certain cleaning situations, determining the correct temperature, frequency, and optimal cleaning solution can be complex. Because each parameter may play a role, there may be a large initial investment in research and development. For example, higher temperatures may reduce cavitation but some oils may require the higher temperatures. It is important to understand how residue, equipment surfaces, and cavitation respond to temperature, frequency, and cleaning solutions.
Alternatively, ultrasonic cleaners can be used as the first step of a manual cleaning procedure to loosen certain residues, which would mitigate the concern for validating an ultrasonic cleaner.
Read also: Development of a Cleaning Process