Double union ball valves have both advantages and disadvantages – figuring out where you need the valve in your pipe system and what kind of control you want to have over the flow will help you decide whether a double union ball valve is the right choice for you.

A PVC gate valve is quite a complex valve compared to more simple valves, like a ball valve, but is fantastic for fine control of flow. The wheel at the top of the valve has about eight/eight-and-a-half turns from fully shut to fully open, which allows for very small movements in the internal workings of the valve. This gives you fine control of your flow.