Pumps used for this purpose must meet strict specifications. “In this application, we are using an ionic brine for the heat-transfer solution in a regime of low temperatures that are much lower than what conventional HVAC pumps could handle without freezing up and having issues,” Phelps said. “It’s mostly the low temperatures ... in some of the cooling regimes that determined the most important pump specification parameters. Energy efficiency was also an important factor because of the high cost of power on Maui.”
From the onset, the NSO set an aggressive construction schedule—and thermal-system component selection and acquisition were no exception.
After a competitive-bid process, the pump contract was awarded to James, Cooke & Hobson Inc. (JCH), a major industrial equipment distributor based in Albuquerque, New Mexico, with offices in Arizona, Texas, California and Nevada.
JCH Sales Engineer Dean Newbold was lead on the project and knew immediately that meeting the aggressive deadlines set by the NSO would be a challenge. “This was not a small project because there were 26 pumps, motors and baseplates needed,” Newbold said.
The pump manufacturer worked closely with Newbold to meet the deadlines by building, testing and delivering 26 American National Standards Institute (ANSI) centrifugal pumps in nine different sizes and configurations, including some with a low-flow configuration. NSO staff monitored pump testing to measure suction pressure (pounds per square inch [psi]), discharge pressure (psi), power (horsepower [hp]), speed (revolutions per minute [rpm]), flow (gallons per minute [gpm]), fluid temperature (F) and vibration.
Exceeding standard ANSI construction requirements, the selected pumps offer design innovations that deliver long-term operational reliability:
- a fully open impeller with rear adjustment capability and twice the wear area of enclosed models for superior handling of solids, corrosives and abrasives
- back pump-out vanes that reduce hydraulic loads and seal-chamber pressure, resulting in smooth, stress-free operation
- standard bronze labyrinth oil seals that keep outside contaminants from entering the lubrication media, which extends bearing life
- extra-heavy casings that incorporate a standard Class 300 wall thickness that extends casing life even when used with severely corrosive or erosive fluids
- heavy-duty shaft that minimizes vibration and shaft deflection, resulting in optimized pump life, and bearings that are sized for a 10-year life span
Because the tight delivery deadlines were met with quality pumps ideal for the application’s requirements, the construction of the DKIST’s exterior thermal-cooling system is right on schedule.