Airset regulators are seemingly simple devices, but care must be taken to ensure the right devices are specified, particularly in safety instrumented systems
Chemical plants and other heavy industrial facilities typically contain many pneumatically controlled valves, actuators and instruments. Airset devices are commonly used to regulate the supply of air pressure to these components. An airset is a specific type of direct-operated, pressure-reducing regulator with an integral filter. It is often overlooked in design, but proper selection is needed for safe and effective operation, which is critical, because these devices are often used in emergency shutdown and other demanding on/off valve applications.
How airset regulators work
As is the case with any direct-operated regulator, an airset senses and maintains downstream pressure to a required setpoint. In Figure 1, the outlet pressure (blue region) is sensed on the underside of the diaphragm, and the airset regulator uses this pressure to generate force and counteract the spring force on the upper side of the diaphragm. The spring casing (in yellow area) is vented to atmosphere.
Figure 1. A typical airset regulator with integral filter and internal relief is shown here.…