One only has to do a Google image search on pharmaceutical equipment to see the clean, sanitary conditions required for pharmaceutical and biopharmaceutical processing. The measurement instrumentation must be able to handle the tough conditions when cleaning and sanitization operations are performed.In a Pharmaceutical Manufacturing article, Ensuring Batch-to-Batch Repeatability in Sanitary Processes, Emerson’s Kyle Knutson defines batch repeatability, consequences of bad measurements, challenges-in clean-in-place (CIP) & steam-in-place (SIP) operations and considerations in the choice of pressure measurements.
The temperature cycling involved can cause instruments like pressure transmitters to drift out of calibration, leading to out-of-spec product, missed time to market and possible recalls.
Not only can loss of product occur from bad measurements but also:
…chemical reactions can occur at sub-optimal conditions, leading to poor batch quality or batch loss; and inadequate filtration can occur, leading to wasted product or the need for additional processing. These problems impact production by reducing product quality and yield.
He describes the cost implications with the 1-10-100 rule:
…for every $1 a manufacturer spends to prevent failure, they would expect to pay $10 to correct a process during manufacturing and $100 to remediate failures after they occur. For the pharmaceutical industry, the costs of failure can be much higher due to government fines and litigation if a finished product must be recalled.
Kyle notes the impact on the transmitters:
When the CIP or SIP process starts, the transmitter will inherently drift due to the quick process temperature rise… When this process ends, the transmitter will try to return to 0 with minimal shift, but the drift from CIP/SIP will affect the quality of the sterilization process; the time back to zero can delay the process and affect batch quality; and the ability to return back to 0% of span affects the repeatability and quality of batches, as well as effects the time between calibrations.
It is important to use only pressure transmitters rated for the harsh conditions of CIP/SIP operations and the characteristics of the application:
What pressures are involved? What temperatures, and for what duration? What chemicals? Once all that is known, the next step is to look for a transmitter that matches those particular conditions. In general, look for a transmitter that has been tested to 140°C, that has a diaphragm compatible with the chemicals to which it will be exposed (typically 316L stainless steel), and that has the appropriate surface finish for the application — typically 32 Ra standard per 3-A requirements, or 15 Ra per ASME-BPE requirements. It should have a crevice-free SST design for maximum cleanability.
Visit the Rosemount Hygienic / Sanitary Solutions page for more on hygienic technologies and their use in consistent and repeatable measurements in biotech and pharmaceutical processes. You can also connect and interact with other pressure measurement and Life Sciences industry experts in the Pressure and Life Sciences groups in the Emerson Exchange 365 community.