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Sanitary Flange Connections

Calibration of Short Sanitary Sensors
Pharmaceutical, food, and beverage producers will employ sensors that connect into their process through the use of sanitary flange connections. These are required to allow them to be cleaned completely while installed in the process. The sanitary flange connection has no threads and has specifications for surface smoothness so that there is no risk for bacteria or other contaminants to flourish in the system.

These sensors serve to monitor that a process is operating as designed to maintain a system temperature as required for production. They also serve to document that the system has been properly cleaned and maintained. The typical calibration temperatures for these sensors are 0°C, 50 to 100°C, and 130 to 140°C. The last temperature is important as it is the clean-in-place or CIP temperature ensuring that no contaminants survive the cleaning process. The typical required accuracy is ±0.5°C.

Sanitary flanges pose a challenge to technicians tasked to perform calibrations because of the shape and size. Their odd configurations have dictated that they be calibrated in an oil bath. In addition to the oil bath, the technicians are also required to use an external temperature reference making the task even more complex.

Oil Bath Calibration Challenges
Oil baths have been a staple used in temperature calibration for a long time. However, they are not without their complications. First, the oil itself is expensive to obtain and to dispose; additionally, the persons using it or potentially in contact with the oil must be trained on handling the oil and the hazards associated with exposure to the oil. It is also a spill hazard and that can be an issue because of the potential release of chemicals requiring a specified clean up procedure, the potential for slips and falls, and the possibility of someone being burned by hot or extremely cold fluid.

A final complication is introduced through the use of the external reference sensor. There is no assurance of consistency between operators, or even from one measurement to another, because there is no method of ensuring that the reference is placed in the same proximity to the sensor, or that it is even properly immersed in the bath such to give a proper reading.

Because of these factors, the process of calibrating these sensors takes quite a bit of time and care and the training is rigorous. In many cases, it is accomplished using multiple baths. While this does reduce the time required, it further complicates the process. It also greatly increases the probability of a spill or a burn. It also requires more of the expensive and potentially hazardous fluid.

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