R.E. Merrill & Associates, Inc.
Application Guidance

Pumps for Semiconductor Ultrapure Water (UPW)

Why ultrapure water is hard on pumps

Ultrapure water is aggressive precisely because it is pure. Stripped of its ions, it pulls them back out of whatever it touches, which makes a metal wetted path a slow, steady contamination source: the pump dissolves into the product. Particles shed from wearing components matter at levels most industries never measure, and extractables that would be undetectable anywhere else show up at the point of use. In a fab, the water system is part of the process, and every wetted component upstream of the wafer counts against the purity budget.

Approaches that get specified

In polish and distribution loops, where purity requirements are tightest, nonmetallic pumps with solid thermoplastic and fluoropolymer wetted parts keep metal ions out of the water entirely. High purity and deionized water piping systems extend the same discipline to everything between the pumps. Upstream, in makeup and membrane feed service ahead of final polish, stainless multistage pumps carry the pressure duties where the purity requirements have not yet tightened. Where each material class belongs in a given plant is a purity question first and a hydraulic question second, which is exactly the order we work them in.

How RE Merrill confirms the selection

For UPW, compatibility means purity: the question is not whether the water hurts the pump but whether the pump hurts the water. We confirm wetted materials against the purity requirements of the loop and factory guidance before we quote, stage by stage from makeup to point of use. Send the duty: where in the water system the pump sits, the purity requirements at that stage, flow, and head, and we return a confirmed selection.

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