Here are five factors to guide you in making a purchase decision.

Not all process chillers are created equal, which means some units are better suited than others for your application. Here are five factors from Ron Spangler, P.E., a senior product manager at Liebert Corp., Columbus, Ohio, to guide you in making a purchase decision.

1 Capacity. A chiller's capacity is directly related to the leaving-water temperature, so be sure to consider it. Instead of simply specifying a three- or four-ton process chiller, factor in the BTU/hr requirement and leaving-water temperature.

2 Flow Capacity. Specify a minimum and maximum flow range. For example, effectively cooling a particular piece of equipment may require increased flow at higher water temperatures. A maximum pressure drop also should be specified to make sure the chiller can deliver the required flow rate. A chiller pump can be sized to an acceptable midpoint based on desired water temperature, expected flow changes and anticipated pressure drops.

3 Stability. Process cooling loads usually cannot tolerate wide temperature fluctuations. A thermal storage tank might be needed to manage a fluctuating load and to limit temperature variance.

4 Ambient Conditions. Unlike comfort cooling applications, many process chiller applications require year-round cooling. This means the chiller must be capable of running in an ambient temperature range of -30 to 115oF (-34 to 46oC). When applicable, high elevation requirements also should be specified.

5 Backup. Downtime equals lost revenue. A redundant chiller or municipal water can be used as emergency backup cooling for a process chiller.