What is NW40-150-LF
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The designation NW40 (also known as KF40, QF40, ISO-KF, etc.) refers to a standard vacuum flange / coupling size. The “40” corresponds to a flange outer diameter of ~2.18 inches (≈ 55.4 mm).
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The “150” in “NW40‐150‐LF” indicates a tube or bore size of 1.50″ (i.e. the internal diameter of the tubing that mates to this flange).
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“LF” stands for Long Flange (sometimes “Long Butt Flange” or “Long Flange / Long Butt”) — meaning this is a flange with an extended “butt” section, essentially a half-nipple or stub length to facilitate welding, joining, or insertion.
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The part is made from 304 stainless steel (standard vacuum hardware material) in the flange version.
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Some dimensional details given by LDS Vacuum for NW40-150-LF:
• A (tube inside length): 1.50″
• B (flange thickness): 0.07″
• C (overall length): 1.58″



