Central Station Steam Company offers "Sliding Gate Trim" because this unique seat design offers simplicity in design, unsurpassed trim life and very good accuracy.

The trim consists of a stationary slotted disc (seat) and a moving slotted disc (plug), which allows us to control the trim orifice to control the flow rate of liquids, gases and steam. Both discs feature a special ceramic based coating for low friction and, because the seats are pre-lapped at the factory and are self-lapping during operation, there is outstanding wear resistance while maintaining long-term Class IV shut-off capability.

The valve design features a straight through flow path and the direction of the disc travel is perpendicular to the flow, not opposed to the direction of the flow. This valve design therefore does not rely on an unbalanced trim design, which allows us to provide a wide range of control with very little hysteresis. Since the flow path is straight, this trim design minimizes turbulence and is therefore generally less noisy that conventional globe valve designs. Since the plug is always in contact with the seat, trim chatter is totally eliminated.

A range of spring-diaphragm actuators are available to position the valve in addition to a variety of valve positioners, should they be required.

In order to select/recommend the right valve for the application, we need to understand what the requirements are so that we can size the valve properly. We would need the following information:

1. 1. Piping: Inlet & outlet size, pipe schedule, material and process connection requirement.
2. 2. Temperature: Temperatures at the various flow rates.
3. 3. Flow Rate: Maximum, normal and minimum flow rates & flow rate engineering units
4. 4. Pressures: Inlet and outlet pressures at the various flow rates
5. 5. Medium: Type of fluid to be controlled.
   • If not a standard fluid, we would need density, viscosity, vapor pressure & critical pressure for liquids.
   • For gases, we would need density, viscosity and compressibility factor. For steam, we would need to know whether we are dealing with saturated or superheated steam.