Why design, when any number of PDPs are available off the shelf?
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"Did you get my e-mail?" - "The biggest problem in communication is the illusion that it has taken place" - George Bernard Shaw, 1856
API 674/676 - top of the pops. What industry (can't find my crystal ball) - if you are pumping chocolate you might not want to design to such a high standard.
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If you can't explain it simply, you don't understand it well enough. (A.E.)