Automated washing principles and common mistakes
Automated washing systems are often used for critical cleaning and drying applications in research, pharmaceutical and biopharmaceutical manufacturing facilities. Typical applications include cleaning of lab glassware and parts from equipment used in the manufacturing of parenterals, oral liquid and solid dosage drugs. A good understanding of washing’s basic principles can help with making the best use of automated washing systems, as well as avoiding typical mistakes which can lead to inconsistent cleaning performance, lower productivity and higher operation and maintenance costs. Such knowledge represents an important step toward operational excellence.
Basic washing principles: TACCTS
A common acronym used in the industry to remember the cleaning parameters is TACCTS (temperature, mechanical (action), chemistry, coverage, time and soil). The cleaning parameters need to be effective at removing the residue on the surface so understanding the nature of the soil should be the first cleaning parameter addressed, even though it’s the last letter of the acronym.
The critical parameter of temperature can apply to the pre-wash, detergent wash and rinse phases. The temperature of the pre-wash phase may vary based on the nature of the soil. For fats, oils and greases, a high temperature, around 82 C (180 F), is preferred. For minerals, a moderate temperature, around 65 C (150 F), is more adequate. For proteins and sugars, a pre-wash temperature around ambient is helpful. Typical temperature for a detergent wash is around 60 to 82 C (140 to 180 F).
Action or force applied to the surface through a dynamic spray device, such as a revolving spray arm, or fixed spray device, such as a spindle, will help dislodge residues mainly through direct impingement and cascading flow.
pH is an important chemical principle which can influence solubility of the soil in the cleaning agent. It’s also important to access material compatibility of the items being cleaned.
One of the most critical principles is coverage. Despite using the best cleaning chemistry and optimum cleaning temperature, if the cleaning chemistry doesn’t come in contact with the soil, then the soil won’t be removed and subsequently rinsed from the surface. Coverage is very important, and it can lead to consistent cleaning performance or consistent failures in automated cleaning.
Similar to the cleaning parameter of temperature, time can apply to the dirty hold time, pre-wash, wash, post-wash rinse, wash two, post-wash two rinses, final rinse, dry time and clean hold time of an automated wash cycle. The length of time may be based on amount of soil, condition of the soil and temperature.
|Use hot water in pre-wash phase when cleaning protein-based soil.||Soil is cooked on surfaces, making it more difficult to remove during subsequent wash phase.||Select cold water for pre-wash wash.|
|Use cold or hot tap water in wash phase when cleaning oily or grease/fat type soils.||Soil is not removed from surfaces, or an extremely long cycle time is required.||Select very hot water for the pre-wash and wash phases.|
|Washing with water temperature outside of the operating range of the chemicals being used||Check operation range on chemical container labels and adjust temperature accordingly.|
|Performing Final rinse with cold water||Very long drying time.||Adjust temperature of final rinse as high as possible.|
|Using chemical(s) with the wrong pH||Very long wash time or improper cleaning.||Use alkaline chemicals for protein and organic soils, use acidic chemicals for inorganic, mineral based soils.|
|Using acidic or alkaline detergents to clean aluminium containers or pH-sensitive load items||Containers or load items will degrade/deteriorate.||Use neutral pH chemistry for these types of materials.|
|Trying to clean heavily soiled and dried load items with low detergent concentration||Wash time may need to be significantly extended.||Increase detergent concentration until reasonable result/time ratio is reached.|
|Using chemistries that create foam in the chamber||Pump cavitation is created, resulting in lower pressure and possible damage to pump.||Use chemicals recommended by manufacturer, or non-foaming detergents.|
|Setting long time for rinse phases||Longer total cycle time.||If rinse water is recirculated, increasing time does not improve rinsing efficiency much. It’s better to shorten rinse time and add rinse phases if need be.|
|Setting high temperature for all rinse phases||Longer total cycle time.||Higher temperature doesn’t typically improve rinsing efficacy. Reducing temperature shortens rinse phases and reduces stress for equipment. Final rinse should be heated to accelerate drying. There may be a need for achieving some level of thermal disinfection, example: cages in Laboratory Animal Research Industry. In this case, heat only last rinse.|
|Using low-quality water for all phases||Poor cleaning performance, spotting due to mineral deposits, higher detergent usage.||Follow supplier’s recommendations for water quality. Adjust detergent concentration based on water hardness. Use mineral free water, at least for final rinse (reverse osmosis, deionized, distilled, water for injection).|
|Using the wrong accessory for the application||Inadequate coverage, poor cleaning performance||Follow supplier’s recommendations for selection of accessories.|
|Positioning load items incorrectly|
|Overloading baskets and accessories||Limited coverage, inconsistent cleaning results||Avoid overloading|
Following is a list of common mistakes that result from a lack of understanding of the principles described above, a description of the outcomes and suggestions as to how these mistakes can be avoided.
Most common mistakes can be avoided by understanding and applying basic principles of cleaning and following manufacturer’s recommendations for loading glassware/parts to be processed and maintenance of the equipment. Automated cleaning of lab glassware, animal cages and racks and components used the manufacturing drug process are very much influenced by TACCTS. Setting these parameters properly will ensure consistent cleaning results, increase your productivity and lower your operation and maintenance costs.
Olivier Van Houtte is Product Manager in the Life Sciences Div. of STERIS Corp. Paul Lopolito is a technical services manager for the Life Sciences Div. of STERIS Corp.