Bummer....When I googled, I managed to pick up some instruction manuals for aircon and marine installation docs that had 5/8ths locknuts listed, but there wasn't a hell of a lot of locknuts listed at supplier sites - might have to check with Bunnings for brass ones - it doesn't matter too much what metal they are since they're on the dry side of the mashtun.
Hi Trough lolly,
Trying not to sound too much out of my depth here, but since my (current) main area of plumbing is airconditioning and heating and cooling, we come across a variety of sizes. With AC, every different split system has liquid and vapour lines running between the compressor and the coils. Always a (small) liquid line running from the compressor to the coils and a (larger) vapour line running back to the compressor. As it comes out of the coils, the refrigerant temperature is still really cold, hence must insulate this line on the way back to the compressor - or get nasty condensation in your plaster walls. I love going off on tangents.
The long and short of it is that still today, the most common pair coil in AC units is a 3/8"x 5/8" copper pair coil. so there are a large number of fittings to suit. In AC, the most common are 1/4", 3/8", 1/2", 5'8", 3/4" and 7/8". The largest I have done was for a add-on cooler and was an 1 /1/8" copper, but all are common depends if the unit is 1 HP, or 2.5HP or 3HP (horse power) etc. all use different copper pair coils.
But your original question about the lock nuts. Hmmm.
I am not an expert here. I know that BSP male/female iron fittings are a standard for threads, but am a little rusty with nust and bolts.
This is what I know.
Nuts and bolts are different. There are metric and there are imperial.
If you needed an 75mm M16 bolt, that would be a 75mm long bolt with a metric thread and a diameter of 16mm. There would be a metric (M16) nut to suit it. I think (this is all from memory) that a 6mm meteric threaded bolt has a thread spacing of 1mm, and the next size up, 8mm, has maybe a 1.1 mm thread spacing - that's not the point. The point is that every bolt diameter has a Metric thread, and a nut to suit it.
The thread patterns are different for imperial bolts. In a previous job, all I did was change rusted bolts over for new ones at an acid plant - fertiliser, not the backyard kind... All the bolts on site were 5/8" bolts (so yes ther are still common usage in Australia), hence needed 5/8" nuts. A 5/8" bolt is almost the same as an M16 (metric 16mm diameter) but a nut would never thread more than 1/2 a turn as the thread patterns certainly don't mach - I think much wider for an imperial pattern.
So still trying to answer your question, go to a bolt shop, and ask them for the fitting. They usually have endless kinds, and are usually really friendly. Take the fitting you want and ask them to find something that fits.
Hope I have helped.
WilBier
