flexpvc Posted July 22, 2015 Share Posted July 22, 2015 Hello, This is Eric from FlexPVC.com We've learned 99.9% of all aquarium people are very specific on their tanks. They go to a lot of expense and effort to get them just perfect. But there is a common mistake amost everyone has in their system: Nominal Ball Valves. Aka, MIP (Molded In Place) ball valves.Why is it a mistake? What does Nominal mean?Nominal means "in name only." For example a 1/2" pipe is not 1/2". Just like at the lumber store a "4x2" is not a 4" x 2". Those are nominal names. A 1/2" Sch 40 pipe is almost 5/8" ID (inside diameter) and almost 7/8th OD (outside diameter.) So why do they call it 1/2"? Just tradition. It's about 1/2", but the tolerance is the OD not the ID. Confusing, I know.Just like a 4x2 (lumber) is 3.5" x 1.75".So what does this have to do with Nominal Ball Valves? Well they are worse. A 1/2" Nominal Ball valves is WAY LESS than 1/2" ID. It's about 7/16". A 2" Nominal Ball valve is about 1.5" ID. If you don't believe me, go look at some.I made a video showing this and put in on youtube along with a solution: (basically if you want a full flow ball valve, you buy the next larger size and use reducer bushings to take it back down to the size of the pipe you want to us.)I hope you found this informative. :-) And now you may know why your 1000gph pump really isn't putting out 1000gph... (well actually that's a whole 'nother post.... )HTHEricFlexpvc.comAll Rights Reserved Link to comment Share on other sites More sharing options...
JasReef Posted July 24, 2015 Share Posted July 24, 2015 Good tip. Thank You! Link to comment Share on other sites More sharing options...
flexpvc Posted July 26, 2015 Author Share Posted July 26, 2015 I made some corrections and update to the above and posted it on our site: http://flexpvc.com/TechArticles/NominalBallValves.shtml Give it a look.:-) Link to comment Share on other sites More sharing options...
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