In this project, one magnetic flow meter was used to measure chilled water flow at the inlet to chiller two evaporator. Insertion vortex flowmeters were used to measure header flow on the chilled water and condenser water loops. The water flow to chiller one evaporator is obtained by taking the difference between the flow at the chilled water header and at chiller two.

Full-bore magnetic flow meters are more expensive than conventional flow meters, but they are far more reliable and require much less maintainence, resulting in lower life-cycle costs. This is largely since there are no moving parts and no disruption to the flow stream.

A significant portion of the first cost of a flowmeter is the installation. The installation of the magnetic flowmeter required the system be isolated and drained. It was installed at the location of an existing annubar flowmeter which was removed. The flange was reused and an air vent was installed to insure against air pockets.

Insertion vortex meters are less expensive and similarly inexpensive to maintain. They are also very accurate but slightly less so than the mag-flo (1% at full scale vs. .5%). This is partly because it must be inserted into the flow. This was the preferred meter for this project; however, the small pipe diameter at the chiller inlet made it necessary to use the magnetic meter to obtain comparable accuracy.

For the vortex flowmeters used, the insertion depth is 3.5" into a 10" pipe. The insertion is necessary to penetrate the edge of the velocity profile to create a vortex. Vortex flowmeters function by detecting vortex frequencies which are directly proportional to average flow velocity. The installation cost for these meters are low as the sensor can be installed while the system is in operation. The meter was programmed and calibrated for the diameter of the pipe and has a remote display for use by the operator. The picture above shows the meter during the installation process.