Advantages of digital sensors in an environmental monitoring system

James Pickering, Director of Environmental Monitoring Systems at ROTRONIC

Environmental parameters are critical to product quality and are therefore monitored and controlled across a wide range of industries. When certain sensitive products are exposed to incorrect temperatures or relative humidity, their quality can no longer be guaranteed.

Why is environmental monitoring so important in the pharmaceutical industry?

Environmental parameters are crucial for product quality and are therefore monitored and controlled in the pharmaceutical industry. If certain products are exposed to incorrect temperatures or relative humidity, their quality can no longer be guaranteed. This is even more important in the cosmetics and food industries, as environmental influences can endanger consumers' lives through product or ingredient degradation, reduced effectiveness/taste, and spoilage.

In the pharmaceutical industry, there are regulations to protect patients and to provide quality-assured, safe, and effective products. The temperature range is established along with other parameters to ensure product quality during the product risk assessment.

When planning a facility, the Building Management System (BMS) is an essential part of the planning process. The BMS controls many services within the facility using sensors located throughout the plant, including the heating, ventilation, and air conditioning (HVAC) of a building. To ensure the BMS correctly controls the HVAC system, an Environmental Monitoring System (EMS) can be installed. The EMS monitors all critical control parameters defined at critical points during the product risk assessment and established during facility qualification.

The GxP quality guidelines developed by regulatory authorities are intended to cover product quality throughout its lifecycle.

The GxP guidelines specify that the area used must be qualified, temperature should be monitored, and monitoring devices must be calibrated according to guidelines.

– Qualified: The qualification of the area is the process of demonstrating that the area meets the requirements for its intended purpose.
– Monitored: Critical control parameters (including temperature) are measured and stored for later use (sometimes up to 18 years or longer).
– Calibrated: The devices used for monitoring display the correct values. The devices are regularly calibrated to ensure measurements always show the correct values.

The regulations do not specify how these requirements should be met. Therefore, the user can decide how to qualify the areas, how to monitor the area, and how often to calibrate the devices.

What is a digital sensor?

A digital sensor is a measuring device that outputs a digital signal. The main advantage of a digital sensor compared to an analog sensor is the information it transmits. While an analog sensor only sends an mA or voltage value (which is converted into a measurement), a digital sensor can transmit much more data, such as:

– Measurement(s),
– Device serial number,
– Device status,
– Calibration data,
– Adjustment data...

All Rotronic digital sensors have integrated memory and can be calibrated/adjusted by the user.

What are the main advantages of using digital sensors in an EMS?

Rotronic's digital sensors communicate with data loggers (wired or wireless), and all communication with the server and database is digital, so there is no loss of accuracy during data transmission. This means that, unlike analog sensors, there is no need for loop testing during installation and qualification/validation of the device.

A major advantage of using digital sensors in an EMS is the ability to utilize additional data and reduce downtime, especially during calibration or service periods.

With analog sensors, calibration can be performed either in a calibration laboratory (internal or external) or on-site if the application permits. When calibration is performed on-site, loop testing is also carried out simultaneously. For calibration in a laboratory, the device must be removed (which causes system downtime). With Rotronic digital sensors, a simple hot-swap can be performed that causes no downtime:

– Manually unscrew the existing sensor.
– Manually screw in a "new" pre-calibrated sensor.

The existing sensor can then be calibrated in a laboratory and either reinstalled in its original location or used elsewhere in the plant. Another advantage is that RMS automatically indicates when a sensor has been replaced thanks to the digital system and the requirements of FDA CFR 21 Part 11/EU Annex 11, along with the audit trail showing the time and date, the serial number of the sensor before replacement, and the serial number after replacement.

RMS offers calibration/adjustment functions with the creation of calibration certificates.

What parameters can Rotronic measure with digital probes?

Rotronic currently offers the following digital sensors:

– Temperature,
– Temperature and relative humidity/dew point,
– Differential pressure,
– Carbon dioxide.

Which digital communication protocol is used?

Rotronic's digital sensors communicate via MODBUS over UART.

– With the AC3001: A user can communicate with the digital probe using RMS-CONFIG software (sensor configuration and calibration/adjustment).
– With the E2-05XX-MOD: A user can communicate with the digital probe via MODBUS over RS485.
– With the RMS-LOG-L or RMS-LOG-L-D: A user can communicate with the probe via MODBUS TCP or the system transmits data directly to RMS via an HTTP protocol.
– With the RMS-LOG-868/915: The system transmits data either via a wireless 868 or 915 MHz frequency to a LAN receiver, which in turn transmits the data via an HTTP protocol directly to RMS.

How does RMS enable integration of third-party devices?

Rotronic offers some environmental parameters. However, other parameters must also be monitored in the pharmaceutical industry. Another parameter measured in cleanrooms is particle monitoring. Rotronic has developed a tool called RMS-CONVERTER-100 to import devices from third-party vendors via their MODBUS TCP communication interface.

What is the PST calibration portfolio?

Michell Instruments and Rotronic, both part of the Process Sensing Technology (PST) group and market leaders in humidity and trace moisture measurement, offer a comprehensive range of temperature and humidity calibration devices and systems.

This includes portable humidity generators for easy verification of relative humidity and temperature probes, pressure dew point dryers, and low dew point generators for calibrating trace moisture sensors and instruments. We not only build custom humidity and dew point calibration systems but also offer ISO/IEC 17025 accredited calibrations for relative humidity and temperature at six locations worldwide.