Regarding the gas source connector

I have 5 years of experience in chemical process control design, and I can offer the following guidance: Generally, the air supply connectors for valves manufactured in China are of the RC1/4 type, while those from foreign manufacturers or those that comply with international standards use 1/4 NPT connectors. In many cases, users only need to use a socket-type straight-through terminal connector. Gas source connection fitting: 1/4NPT-Φ8*1 or RC1/4-Φ8*1. I recommend using pipes with a diameter of Φ8*1 as the standard; those with a diameter of Φ6*1 are already obsolete, as they were used in old valves with low gas consumption. Pipes with a diameter of Φ10*1 are generally used in systems with two or more cylinders, and such high gas consumption is rare; therefore, Φ8*1 is the standard choice. The following pipe materials are available for selection: copper pipes, nylon pipes, and stainless steel pipes. In areas exposed to corrosive mist, I personally recommend using copper pipes or stainless steel pipes with a PVC coating :)

Reply to 2# meimei_____: We use quick-connect connectors, with a small metal piece inside that holds the main tube in place. Since the connectors get soaked in water and the water is corrosive, it’s been difficult to find a suitable connector.

Download Volume 3 of SMC Pneumatic Pipeline systems – a fairly comprehensive collection of plug-type connectors

There are mainly two types of instrument air connectors that are used over the long term in the petrochemical industry: steel ferrule connectors and copper pneumatic piping connectors; it is sufficient to clearly specify the pipe specifications in the material plan. You can check it out at Yangzhong Hongchang Instrument Valve Co., Ltd. at http://www.yzhcyb.com/Product-24.html

If you have no budget concerns, go with Swagelok; if budget is a concern, find a company in China.