Differential Pressure and Temperature Monitoring in a Hospital Cleanroom

Accsense A1-01a Wireless Environmental Data Loggers

CAS DataLoggers recently provided the wireless pressure and temperature monitoring solution for a hospital maintaining a surgery cleanroom to protect patients from a variety of environmental contaminants. Staff entered and exited through airlocks and were required to wear cleanroom suits before entering. Air blew into the room through HEPA filters to maintain a particulate-free environment, which also had to be maintained at a positive pressure so that in the event of a leak, air would leak out of the chamber, preventing unfiltered air from entering and contaminating surgeries--otherwise, microbes and other contaminants wouldn’t be forced outside. There were 2 differential pressure points located inside and just outside which needed to be continually monitored, and the cleanroom’s ambient temperature also needed to be recorded. In the event of equipment failures, such as when the HEPA filters routinely became clogged or plugged, or the blower system went down, contaminants would quickly enter and remain in the room, forcing a halt to surgeries until maintenanced. To detect these failures immediately and preserve the room’s integrity, management began searching for a general purpose wireless datalogging solution to record general environmental measurements. This system needed to feature 4-20mA inputs to connect with commercial pressure transducers for effective leak detection as well as feature an ambient temperature sensor. Additionally, whenever the differential pressure dropped or temperature varied, the hospital required an alarm to instantly contact staff so that equipment could be serviced or replaced without delay. 

The hospital installed 3 Accsense A1-01a Wireless Environmental Data Logger Pods to monitor the room’s ambient temperature and pressure, along with an Accsense B1-06 Wireless Data Logger Gateway with built-in 10/100BaseT Ethernet which enabled connection between the pods’ data and the Internet. CAS DataLoggers also supplied 4 Dwyer E1-36 pressure transducers to monitor the differential pressure inside and outside the surgery cleanroom. The Accsense wireless installation was quickly and easily accomplished, with virtually no impact on the hospital’s existing infrastructure—all the data went out to the Web right away. Additionally, no costly training sessions were required since the system’s operation was both simple and intuitive.

The Accsense general purpose sensor pods enabled continual monitoring of the cleanroom’s pressure and temperature, equipped with external 4-20mA and 0-5V inputs as well as internal ambient temperature, humidity, light and vibration sensors. The data loggers also featured 2 digital inputs and could operate on either battery or AC power. Each pod also included a screw terminal connector for connection with a wide range of external analog sensors, as well as a +5Vdc output to power external sensors. The pods’ wireless gateway supported as many as 16 sensor pods, as well as DHCP and static IP addressing. Diagnostic LEDs gave clear indications to personnel as to how to proceed. Both the pod and gateway ranged out to 250' and 90' indoors (with pods able to act as repeaters for other's signals), utilizing a 250-sample data buffer to compensate in the event of a power or internet outage.

Additionally, the Accsense wireless monitoring and alarming system provided the hospital with cloud-based data storage and reporting for hassle-free monitoring. Once connected to the wireless gateway, the pods monitored and logged the pressure and temperature data, giving staff the ability to view and remotely access their data in real-time. The gateway could send all the data to the secure cloud server at Rackspace or as a local ASCII stream, which personnel could then incorporate into their own custom software including LabView. Data online could easily be downloaded as a CSV file and loaded into most database applications. Hospital staff downloaded measurement data for offline analysis, signed in to access reports and graphs, and administrators could modify the system configuration from anywhere an internet connection was available. Sophisticated alarms monitored the incoming data and sent email, pager or phone warnings to multiple recipients whenever an alarm was triggered. The hospital’s Accsense online account gave instant access to charts showing all measurement history with ranges as narrow as 5 minutes or as wide as 90 days, and also offered a customizable interface with a dashboard showing the most recent measurements from all sensor pods.

The hospital benefited from installing the cost-effective Accsense wireless environmental monitoring system in its surgical cleanroom, most significantly by constantly maintaining its differential pressure and ambient temperature via continual monitoring and alarming. Now personnel were immediately contacted when vital parameters suddenly went out of specification, eliminating delays between equipment failure and staff response. This greatly improved surgery safety conditions and ensured the integrity of the cleanroom and the hospital’s safety procedures. The system even continued to log during power or internet outages and kept all data encrypted and secure on the Rackspace servers.