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      The future of the JD Forum   07/31/18

      Thank you all for your participation on the JD Forums.  We have enjoyed answering your questions, providing project advice and technical assistance on this forum for a number of years. We believe that there are now better ways to provide this service for our customers and the community. With that in mind, we have made the difficult decision to discontinue the Jamestown Distributors Forum.   Our JD Tech Team is committed to being your trusted technical resource, and we encourage you to reach out via email, phone, social, product reviews, and to post questions using the Q & A 'Ask A Question' function on all product pages. Additional information can also be found on product page Technical Data Sheets (including detailed usage instructions and application data).   Thank You Jamestown Distributors 

Seacocks and Ball Valves

2 posts in this topic

Posted Image

A seacock is made to fit a thru-hull fitting which is NPS (national pipe straight) threads.  The top of the seacock is NPT (national pipe tapered) thread to take a hose barb fitting.  It is important that the thru-hull fitting fit all the way onto the base of the seacock which will be significant threads seating in the base providing a strong leak proof seal.



Ball valves: Posted Image

Ball valves have NPT tapered threads on both ends and should not be used with a thru-hull fitting below the waterline.  Since the thru hull fitting is straight thread and the ball valve is tapered, when screwed in, there will only be about 3 to 4 threads before it binds up.  In a thru hull situation, there is only a small amount of the thru-hull fitting on the ball valve and with time and corrosion, any pressure placed on opening or shutting could cause the fitting to fail.

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