Sizing skin fittings

prv said:
Right, and the answer to that specific question is "look up a table of BSP sizes, go down the 'major diameter' column until you find the value you measured, then run across to find out what BSP size that is". Or, assuming he can measure the bore instead, rely on the historical basis of the system and the relatively large gaps between sizes and say "it's the one closest to the bore size in inches". That'll work fine for skin fittings, but it's not official, and he shouldn't expect the measurement to be exact.

Pete
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Again, a set of Zeus tables will give all that information and also give the information in Metric and NPT should the OP wish to purchase a French or an American fitting.
 
cryan said:
Again, a set of Zeus tables will give all that information and also give the information in Metric and NPT should the OP wish to purchase a French or an American fitting.
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For plain good old BSP in post # 14 above or readily available many times over on-line.
 
I would still say my original answer was the correct one for the question even if it ws an oversimplification

But is this not become another case of forum nit picking?
 
scottie said:
I would still say my original answer was the correct one for the question even if it ws an oversimplification

But is this not become another case of forum nit picking?
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Yes, you were correct; but it didn't answer the OP who wanted to know how to relate the OD of the thread to the BSP "ordering size".

Not nit-picking, we are just trying to reduce the wrong or ambiguous information in the thread.

prv said:
Unless I'm reading it wrong and he really does think that the thread on a 1" BSP part is an inch in diameter, in which case he's a moron.
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Well Vic and I both read his replies that way, but I couldn't possibly comment further :)
 
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Wow! Thanks all! I should give a bit more information. I'm really looking to replace existing big white plastic ones. They're deck drains (above waterline) and they will have to mate-up with the existing plastic elbows. As long as I can get the right thread size, the bore won't matter that much - I just wondered if they were usually sold on bore size (nominal) - which it appears they are. The main two are big (must be 1.25" or so) bore. In my case, it's the thread size that's critical (so they (a) go through the existing hole in the hull and (b) mate with the elbows on the inside.
 
VicS said:
For plain good old BSP in post # 14 above or readily available many times over on-line.
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Yeah, but a set of Zeus tables in your shirt or boilersuit pocket will instantly add kudos and an air of professionalism in front of your oppos. I think it even ranks above the pencil behind the ear.
 
Avocet said:
Wow! Thanks all! I should give a bit more information. I'm really looking to replace existing big white plastic ones. They're deck drains (above waterline) and they will have to mate-up with the existing plastic elbows. As long as I can get the right thread size, the bore won't matter that much - I just wondered if they were usually sold on bore size (nominal) - which it appears they are. The main two are big (must be 1.25" or so) bore. In my case, it's the thread size that's critical (so they (a) go through the existing hole in the hull and (b) mate with the elbows on the inside.
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Measure the outside of thread diameter and compare with the tables in my earlier post. ( or Zeus)
 
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cryan said:
Yeah, but a set of Zeus tables in your shirt or boilersuit pocket will instantly add kudos and an air of professionalism in front of your oppos. I think it even ranks above the pencil behind the ear.
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Dont worry. Copy of Zeus here. Always within reach.
 
Thanks all. Another question on the same topic, if I may? These big bore, above waterline, plastic fittings seem to come most commonly in either nylon, acetal or Delrin (the latter, I think, being a trade name for acetal)? I notice on some of Avocet's old ones, that the plastic has gone "chalky" and crumbles into a powder if scraped with a pen knife blade, in areas exposed to UV. Any recommendations on the rival merits of each material? I'd like to avoid whichever sort has gone chalky - unless there's some other good reason not to?
 
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