Pharmaceutical Filling Needles- Passivation, Ultrasonic Cleaning, and other Cleaning Considerations

October 9, 2014

One area of pharmaceutical processing that we’ve been spending an increasing amount of time at Holland is the world of final product fill and finish. Our last post focused on vial and syringe filling technologies commonplace throughout the industry. Today we’ll be take another look at the fill needle itself and cleaning considerations following manufacture- specifically, ultrasonic passivation.

To begin, ultrasonic cleaning is a process that uses ultrasound and an appropriate cleaning solvent to clean items. Ultrasonic cleaners are fitted with transducers attached to the bottom of the cleaning tank that create vibrations at high frequencies- measured in thousands of cycles (kHz)- and send sound waves through the cleaning solution. The waves create millions of cavitation bubbles that implode on the surface of the material. This cavitation effect lifts contaminants off of the objects being cleaned.

As a corollary to this, passivation, which we’ve touched on before, is used in a wide range of industries to remove free iron by beefing up the passive, chrome oxide layer of stainless steel. Passivation processes in the pharmaceutical industry are generally regulated by the ASTM, specifically ASTM guideline ASTM A 967. The most common type of passivation used throughout the biotech industry is citric acid passivation because it is a low hazard cleaning agent and is biodegradable. Common steps in all passivation procedures include cleaning prior to passivation, submergence in a hot acid bath for approximately 20-30 minutes, followed by a water rinse and drying.

This begs the question- how do you clean both the inside and outside of something as small as a needle cannula? The answer we’ve arrived at is a multistep ultrasonic cleaning process that we feel is most effective in removing free iron and other surface contaminates present in fill needles following manufacture, while protecting the needle design and ensuring superior performance.

As previously mentioned, Holland has been doing citric acid passivation in house for quite some time. We’ve found that applying ultrasonic energy to the process offers two key advantages in the processing of small ID components- speed and thoroughness. The minute bubbles generated by the ultrasonic bath work on all surfaces and are particularly effective at penetrating the small ID’s of fill needles. This allows us to clean both the inside and the outside of the needle in a matter of minutes.

A typical three step ultrasonic needle passivation process starts with the parts being lowered into an ultrasonic citric acid bath. Both temperature and pH of the bath are closely monitored. The cleaning solution and cavitation created by the ultrasonic bath greatly increase the ability to clean both the inside AND the outside of the needle. Once the appropriate temperature and pH have been reached, the parts are placed into the bath for a specified period of time- usually about 20-30 minutes.

At the end of this time period, the parts are removed from the acid bath and placed into a second ultrasonic bath for an ultrasonic water rinse. This step helps remove any contaminants the citric acid pulled out- again on both the ID and OD of the needle.

The final step consists of a final water rinse without any cavitation. Fresh water flows across the parts, removing final contaminants prior to air drying.
So there you have it- a simple, three step process that ensures your filling needle is as clean as all of the other stainless in your facility. At Holland, we’ve been working with passivated stainless steel parts for over 60 years. We’ve been able to leverage that experience to develop robust solutions that assure our customers they receive only the highest quality product because at Holland, we understand that the process is the product. If you have any questions about your next pharmaceutical filling needle application, contact a Holland Sales Engineer today.