Home valve commonly used in the purchase of coup: optional visual inspection valve, the surface should be no blisters; plating surface should be uniform, should pay attention to whether there is peeling, cracking, scorching, exposed, peeling, dark spots and obvious pitting and other defects ; Spray the surface tissue should be fine, smooth and uniform, no sagging, exposed defects. First, understand the valve knowledge: Civil valves Commonly used by ordinary households are generally gate valve, ball valve, triangular valve and other forms, usually iron or copper. As the mechanical properties of copper alloy, with less rust, corrosion resistance advantages, so the copper valve has gradually replaced the iron valve. Triangle valve surface are basically used electroplating, its role is not only to control the flow of pipeline media, but also play a decorative role. Triangle valve is generally connected to the pipe and water hose for the faucet, toilet water supply, there are connecting pipes and water hoses for water heater. Gate valve is basically used for the connection of pipe and water meter; the ball valve is used for the connection of pipeline and water heater; the ball valve is more convenient than the opening and closing than the gate valve. At present, most of the connection between pipe and water meter adopts ball valve. Second, to master the purchase of civilian valves: According to the different requirements of users to choose different types of household valves: 1. Optional visual valve, the surface should be no blisters; plating surface should be uniform, should pay attention to whether the peeling, turtle Cracks, burns, exposed, spalling, dark spots and obvious pitting and other defects; spraying surface tissue should be fine, smooth and uniform, no sagging, exposed defects. The above defects will directly affect the service life of the valve. 2. Valve pipe thread is connected with the pipe, the purchase of visual inspection of the surface of the thread has no dents, broken teeth and other obvious defects, it is important to note that the effective length of the pipe thread and the screw connection will affect the reliability of the seal Sexuality, purchase should pay attention to the effective length of pipe thread. General DN15 cylindrical thread effective length of about 10mm. 3. Gate valve, ball valve is generally marked on the valve body or handle nominal pressure, optional according to their own needs. 4. Replace the existing gate valve or ball valve, we must find out the length of its structure, so as not to buy after the installation. 5. Triangle valve pipe thread with internal and external thread two, according to the need to buy; also note that there is currently on the market part of the triangle valve made of zinc alloy, the valve price is lower than the average product, but Corrosive and cause rupture. 6, should be as regular as possible in the building materials stores, shopping malls, so product quality can guarantee.