This application story outlines a solution for a common challenge in data center management: maintaining precise air pressure control in an underfloor plenum to ensure efficient cooling. The customer needed to monitor a very low pressure range and integrate the sensor data into their existing network management system using SNMP for high-frequency polling.
- Application: Real-time monitoring of underfloor plenum differential pressure in a data center.
- Challenge: Required a low-range (±25 Pa) sensor with a wireless connection to an Ethernet network that supported SNMP.
- Solution: A combination of a DPS series pressure transmitter, an IWTxT series wireless converter, and an IWR-PORT series wireless-to-Ethernet gateway.
- Benefit: Provided a non-disruptive wireless installation and seamless integration with the existing network infrastructure, allowing for precise control of the air handling system.
Maintaining precise environmental control within a data center is critical for ensuring the operational stability and longevity of high-performance computing equipment. A key aspect of this is managing the airflow from Computer Room Air Handler (CRAH) units, which often involves regulating the air pressure within the underfloor plenum of a raised floor system. A customer required a solution for monitoring very small pressure differences in their data center plenum to provide real-time feedback for adjusting their CRAH units. The goal was to maintain a constant, stable pressure under the raised floor to ensure consistent and efficient cooling across the entire facility.
The application demanded sensors capable of accurately measuring a bidirectional differential pressure in the very low range of -25 to +25 Pascals. A primary technical requirement was that the pressure data had to be accessible over the local network using the Simple Network Management Protocol (SNMP). This would allow their existing network management system to poll the sensors for data at a high frequency, with a desired interval of five seconds or less, enabling rapid adjustments to the CRAH units in response to any pressure fluctuations. Furthermore, a wireless solution was strongly preferred to avoid the cost and disruption of running new cables through the sensitive data center environment.
The proposed solution consisted of three components working together to meet these specific demands. The core measurement is performed by a DPS series low differential pressure transmitter, specifically configured for a ±25 Pa range. This sensor utilizes a wear-free inductive measurement system, ensuring long-term stability and reliability, which is essential in a 24/7 data center operation. Its high sensitivity at very low pressures makes it ideal for detecting the subtle changes in the plenum. The sensor provides a standard 4-20mA analog output signal that is proportional to the measured pressure.
To meet the wireless requirement, an IWTxT series wireless transmitter is connected to the pressure sensor. This battery-powered unit is designed to convert the 4-20mA signal from any standard transmitter into a wireless signal. It powers the pressure sensor, takes a reading, and transmits the data at user-defined intervals. This approach eliminates the need for extensive and costly cabling back to a central monitoring point, offering flexibility in sensor placement to ensure optimal monitoring of the plenum pressure.
The final component is the IWR-PORT series wireless-to-Ethernet gateway, which receives the encrypted data from the wireless transmitter. This gateway acts as the bridge between the wireless sensor and the data center’s local area network (LAN). Crucially, the gateway’s Ethernet port supports both Modbus TCP and SNMP protocols. This directly addressed the customer’s primary requirement, allowing their network management system to poll the gateway for the pressure data from the DPS sensor using SNMP at the required high frequency. The IWR-PORT can manage data from up to 128 separate wireless sensors, providing a scalable solution for future expansion.
DPS Low Differential Pressure Transmitter
- Differential Pressure Range: -25 to 25 Pa diff
- Output Signal: 4-20mA 2 wire, 12-31Vdc supply
- Output Configuration: 2 wire 4-20mA, linear range
- Overpressure Protection: 5x ranges
- Accuracy: 1% FS
- Pressure Connection: 6.6mm dia x 11mm barbed connections
IWTxT Loop Powered 4-20mA Input to Wireless Transmitter
- Part No: IWTxT-00
- Input: 4-20mA
- Power Supply: AA Cell Lithium Ion 3.6V Battery
- RF Output: 2.4GHz 3dBm Tx Power
- Antenna Type: External SMA Connector
- Enclosure: ABS IP67 with built in battery
IWR-PORT Wireless Sensors to Ethernet Gateway Receiver
- Part No: IWR-PORT-E
- Wireless Receiver: Ethernet port with SNMP