Page 53 - PCMI Journal December 2021

Maintenance Tips For PCM Etching Equipment
Kirk Lauver, Marketing and Customer Lab Manager, Chemcut Corporation, US
12/6/21
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Maintenance Tips For PCM Etching Equipment Pumps
Affinity Laws For Centrifugal Pumps* K=Constant
Keeping The Impeller The Same, • Output Pressure = K(RPM)2
• Power Required = K(RPM)3
• Volumetric Output = K(RPM)
Keeping The RPM The Same
Output Pressure = K(Impeller Diameter)2 Power Required = K(Impeller Diameter)3
Volumetric Output = K(Impeller Diameter) • Power Required = A function of the mass moved across a pressure change
in a unit of time plus mechanical losses
• Output Pressure And Power vary linearly with Specific Gravity
*For typical PCM solutions
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Maintenance Tips For PCM Etching Equipment
Pumps
Examples
We keep getting impeller wear even though the gap is correct.
Check the motor for excessive shaft movement, ex. Bad motor bearings.
The developer has 30 psi when it’s started, but the pressure drops to 18 after a few minutes.
Check for foam in the solution, Suspended air lowers the Sp. Gr. And makes the fluid compressible
The old etcher was converted to a developer, as an etcher the pressure was 35 psi now it’s only 25.
That’s correct. The reduced Sp. Gr. Causes lower pressure, Check if a larger impeller is available.
When using 48° ferric the magnetic recirculation pump doesn’t work, even though the motor runs.
The pump power required exceeds the magnetic coupling flux. Partially close the discharge valve to reduce the flow (the power required). Switch the pump off then on again then recheck.
After rebuilding the pump and installing a new motor we only get 6 psi, it was 25 psi.
6 psi is one quarter of the original. Check the motor, is it 1725 rpm instead of 3450 rpm(60 Hz)?
Issue 138 December 2021 PCMI Journal 53
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