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D3835 - 16 Question

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AbidingDude

Mechanical
Aug 17, 2015
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Hello, I'm trying to make sense of one of the specs called out in the rheometer standard. Section 6.4 talks about the specs of the piston. The part I'm having trouble with is:

...The land of the piston shall be 0.0254 ± 0.007 mm (0.0010 ± 0.0003 in.) smaller in diameter than the barrel and at least 6.35 ± 0.13 mm (0.250 ± 0.005 in.) in length...

It's the last part I'm having trouble with. It says the length should be "at least" 6.35. If it's "at least", how can it have a plus/minus tolerance? "At least" implies 6.35 or greater.
The only other thing I can think of is that they might mean the manufacturer of the piston can make the piston land whatever length they want as long as it's held to a 0.13mm tolerance.
Does anyone have any insight on this?

TIA!
 
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