How to distinguish between various piece ball valves

How to distinguish between various piece ball valves?
Distinguish from the structure.

One-piece ball valve is

inside the ball, PTFE ring, lock nut composition, the ball slightly smaller diameter than the pipe diameter, similar to the Cantonese-style

ball.
Two-piece ball valve is composed of two parts; the seal is better than a ball valve, ball diameter and pipe the same diameter,

than a ball valve for easy disconnection.
Three-piece ball valve is composed of three parts; the middle of both sides of the valve

cover and valve body, three-piece ball valve is different from the two-piece ball valve ball valve and where is the demolition of

maintenance.
     Distinguish from the pressure
Three-piece pressure is much higher than the one-and two ball valves.

Outside the main three-piece ball valve fixed by four bolts, fastening to play a good role. Casting pressure valve can be reached 1000psi

≈ 6.9MPa. Forging a higher pressure is necessary to use the body.
    From the economic point of distinction
A ball valve as the main material is less than the other two categories,

best prices, and Cantonese use the same ball. Two ball valve prices is higher than a

style, three-piece body in a higher pressure capability consists of three parts, materials than the other two categories.
From the original1checkvalve
.