Copper valve, screw valve, copper lock valve difference, which should be in front of the water meter, which should be in the water meter after their role?
Installed in water, is usually a locking valve installed in the water in the water in front of oneself, the common gate valve or ball valve installed in the water after, in order to form after failure to remove and close the valve without water and other operations.
As for the thread valve you said, I'm not sure what it is, but the thread is a connection. The DN15-DN32 is threaded, and the bigger DN40-DN300 is the flange connection
You should be called copper valve gate or ball valve type, can be manually operated switch. Copper lock valve is usually called the locking valve, ball valve is a kind of, but it is with a lock, each type or style are supporting key residents if no key can not arbitrarily switch the main valve to stop water or heat etc.!
