There are many valve options, and many types are used. Examples include simple solenoid, motorized two-way and three-way valves, and six-way valves. Valves can be electric/voltage-operated or pneumatic/air-operated, with an air compressor system required for the latter. The two primary valves used in a brewery are ball valves and butterfly valves. They are used to control the flow of most types of gases or liquids across a wide range of temperatures and pressures.
A ball valve is (in simplest terms) a ball with a hole running through it (Figure 24.8). Turning the valve positions the hole to either block, partially block, or complete the flow line through the valve. Advantages of ball valves include an excellent seal with little to no leaking when the valve is fully closed.
Butterfly valves are constructed using a round stainless-steel disk the diameter of the surrounding pipe that turns using connections at the top and bottom of the disk (using a handle attached to the top connection). One of the advantages of butterfly valves is that they are relatively inexpensive to build, clean, and maintain. Although generally cleanable there are two places where the disk attaches to seal/valve body (where particles and/or microbes can be trapped).
These valves are mostly used to control the flow of water or air rather than juice or beer. If they are installed at the correct angle (usually around 45° from the upright position), they are free draining around the weir and contain no pockets or crevices for liquid or solids to accumulate. Diaphragms are made of several materials including EPDM (ethylene propylene diene monomer) and EPDM-backed Teflon or Buna (synthetic) rubber (Figure 24.10).
Globe valves, so-called because of their outside shape, are widely used in plant piping. They are suitable for manual and automatic operation. Globe valve can be used for regulating flow or pressures as well as complete shutoff of flow. It may also be used sometime as a pressure relief valve or as a check valve.
Flow Control Valves
Flow control valves are operated through a computer screen or through an automation sequence controlled by a programmable logic controller (PLC) or other types of controllers. The actual opening or closing of the valves is typically initiated by an electrical signal to a solenoid valve that allows compressed air into the valve actuator to change its state.
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