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The Problem: Hospitals, universities, office buildings, data centers and pharmaceutical manufacturing plants are all looking to measure and monitor the flow rates in their chilled water plants in order to save energy and operate more efficiently. However, adding flow meters to existing lines with many traditional methods can be costly in terms of material, labor and down time.

The “Traditional” Approach: In the past, various types of flow meters have been used including mag meters, vortex meters, or annubars and pitot tubes with differential pressure transmitters. Many of these devices require the installation of flanges and/or differential pressure transmitters and “impulse” lines. Modifying these existing lines is difficult, cost-prohibitive and time-consuming.

Major New York City Hospital: With 8”, 12”, 14”, and 24” lines, facilities engineers wanted a cost-effective solution with minimal welding and down time.

The Solution: Insertion turbine meters manufactured by Onicon were selected. A “weldolet” was installed in each line with an isolation valve so that the meters could be inserted while the chilled water lines were in use. With the “dual” turbine units, the upstream and downstream lengths of required straight pipe length were minimized. Other traditional flow meters would have required twice the amount of straight pipe run in order to provide an accurate measurement.

The Onicon turbine meters have an accuracy of +/- 1% of rate with a rangeability of 10:1, and as much as 50:1 with an accuracy of 2%. Each meter is “wet” calibrated to NIST traceable standards.

Meters are powered by 24 VDC or 24 VAC, with output choices of 0-10 VDC, 4-20 ma, or pulse, both of which can be connected to a building management system.

By adding inlet and outlet temperature sensors, an Onicon BTU unit can display and totalize BTUs for billing purposes. This BTU unit can be supplied with MODBUS, BACnet, LONWORKS, JCI-N2, Siemens-P1, or other data acquisition software including GE’s Proficy Process Solutions.

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