Thread Types used on spa filters, valves, unions

Identify the thread type used on various spa components including filter cartridges, pump unions, diverter valve caps and more
Thread types - Acme, V, Metric, NPT, MPT, FPT

The majority of threads in the spa industry are imperial sizes. It's rare to find a metric thread.

Buttress thread - used on some pump unions, diverter valve bodies
V shaped - used on some pump unions, diverter valve bodies, filter cartridges
Acme - used on numerous filter cartridges

Most threads are straight threads, but numerous fittings including pressure switches use a tapered thread.