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Real-Time, Multiple-Location Temperature Monitoring

Fri, 08/31/2007 - 8:00pm
G. Peter Sawiris, Ph.D., and Robert G. Rohwer, Ph.D., VA Medical Health Care System


Environmental changes in sensitive laboratory facilities call for continuous surveillance and online decision-making, and it is in this area that IT technologies have become an invaluable resource. A newly developed multi-agent system has been deployed for monitoring and assessing environmental attributes using thermocouple probe sensor data. The system monitors and validates measurements coming from several sensors to assess temperature and to fire alarms to appropriate recipients when needed.

Background

The WELMS-12 Web-enabled laboratory monitoring system provides continuous real-time temperature monitoring and data visualization of up to 12 different locations from within a facility and over the Internet. The unit can be integrated into a local area network (LAN) of a diverse facility, providing easy visual access to data from virtually any location.

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Analogue data (voltage changes) from the temperature sensors are converted to digital data by the Multiscan/1200. The unit features RS-232, RS-422 and IEEE 488 interfaces for connecting to a desktop PC. The unit is preconfigured for RS-232 communication but can also utilize the IEEE 488 connection for high-speed recording rates (1000 readings per second, or 1.0 kHz).
The unit monitors temperatures ranging from -269 C to 400 C (-452 F to 752 F) at recording rates of up to ten readings per second (10 Hz). It also includes an alarm system with a variety of notification methods when a particular reading goes out of pre-programmed limits. These include audible notifications and those via E-mail, pager, text message, computer monitor or Web page. The notification methods can be utilized independently or in any combination. Equipment currently monitored with the unit includes: refrigerators, freezers and ultra-low freezers, animal rooms, cold rooms, stability chambers, liquid nitrogen tanks, autoclaves and incubators.

New Environmental Monitoring Technology

Monitoring a laboratory or building via a single Web page enables easy access to a single centralized alarm and data source rather than having to retrieve data from each individual site where the recordings are being generated. The system also reduces the costs and time associated with paper-based charting or manual documentation tasks while increasing accuracy. Data can be immediately viewed in real time, analyzed for trends, or stored for historical archive purposes.Individual components of the WELMS-12 include probes for temperature recording (thermocouples), a hardware unit for multiplexed analog-to-digital data conversion (ADC), and computer software to both record and visually output temperature data locally and to the Internet.

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Continuously updating data chart of temperature versus time generated by the WELMS-12 for monitoring ultra-low laboratory freezers. The system is configured so that a high-temperature warning system activates audible, visual and E-mail alarms when the temperature deviates 10 C from the set point. The system is also equipped with a continuous-charge battery backup so data and alarms can still be reported during a power failure via a LAN and also by modem/landline.
Click to enlarge.
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Temperature values as a function of time for the most commonly used type K (Chromel/Alumel) thermocouple. In this example, three sensors are placed in two different autoclaves during a steam sterilization cycle. Thermocouples 1 and 2 illustrate an example of how differential temperature information can be obtained by placing multiple sensors in different areas within an autoclave or other equipment. Type K thermocouples have a sensitivity of ~41 mV/C.
Click to enlarge.

The type T copper/constantan thermocouple with a 0.1 C resolution is best suited for a wider variety of applications. Measurements for more specialized temperature and location applications can be obtained with other thermocouple types (J, K, E, R, S, B and N), which have more accuracy over a narrower useful application range and are better suited for more specific ambient conditions (reducing, oxidizing, vacuum, hydrogen, sulfur or inert atmospheres). The direct conversion ADC unit is contained in a compact 1.750 3 16.750 3 120 enclosure, utilizes easy-to-use, preprogrammed Windows-based software for real-time readings and has extensive user-friendly features and benefits.

Online Performance Demonstration

The system is supplied with a dedicated i686 Linux Internet client/server account so that Web site setup is not required. A demonstration version of the system can be viewed online at welms.domaindnseye.com.

Conclusion

A number of setup variations and the incorporation of new technologies are possible for future research and development of the WELMS-12. Because of the system’s versatility, many possibilities exist that can extend the system functionality beyond the current configuration described. These include advanced diagnostic algorithms for various equipment and experiment monitoring and more extensive development of laboratory automation systems. Additional parameters important in a research facility include gas detection, particulate/aerosol detection, air quality, explosive detection, industrial hygiene, water analysis, radiation measurement and protection, security, emergency power generator monitoring, monitoring of desktop computer electronics software, and monitoring of animals facilities.

For more information, contact G. Peter Sawiris, molecular biologist with VA Medical Health Care System, at gsawiris@gmail.com or by phone at 410-605-7000 x6497 or visit http://welms.domaindnseye.com.
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