Double ferrule tube fittings are the most common style of instrumentation fittings, and they can also be purchased in brass materials.
Quality tube fittings and adapters at Brennan Industries
Brennan Industries N2406-B Double Ferrule Tube Fittings - Brass
Straight Brass Fittings PL-MIFS Straight
Brennan Industries N2403-B Double Ferrule Tube Fittings - Brass
Brennan N2404-08-08-SS Stainless Steel Compression
Brennan Industries
N2406-02-04-SS Reducer - Compression Fittings, N2406 Series
Brennan Industries Instrumentation Double Ferrule Tube
5405 Tube Fittings and Adapters by Brennan Industries
Ferrule Fittings at best price in Mumbai by M. S. Forging Works
Brennan Industries N2705-LN-08-06-B Brass Straight Double-Ferrule
Brennan Industries N2706-LN-B Double Ferrule Tube Fittings - Brass