346 Series – Pneumatic Non-Return Valve Asco Joucomatic Numatics Non-Return Valves Pneumatic non-return valves are available with threaded and pushfit connections. Size : 4mm to 8mm | M5 to 1/2″ Fluids : Air – Inert Gas Body : Plastic (Pushfit) | Brass (Threaded) Seal : NBR (Nitrile)