Valve designer and manu- facturer PSV Mitech reports that a computer-ised control valve sizing pro-gramme, one of the products in its stock, allows users to choose between control-valve sizing and actuator sizing to specify the correct type of valve used in a specific application.

The actuator-sizing programme caters for PSV Mitech’s rotary and linear pneumatic actuators. In both cases, the correct actuator model is selected from the complete range, based on certain input information.

The choice is limited to globe, sweep angle, butterfly or disc valves. Gauge and absolute valves are also available with measuring units in kilopascals and bars. If gauge units are selected, a window appears in which the atmospheric pressure must be entered. Upstream and downstream pressures must then be entered for a choice of units.

Temperature can be entered in degrees Celsius, Kelvin, Fahrenheit or Rankine, while, the choice of flow rates is even greater since both mass and volume flow rates are catered for. The most common are cubic metres per hour and tons per hour, but for those who work more comfortably with litres per second, the choice is available.

A useful feature is a check-box, known as convert units, that, when checked, newly selected units − whether for pressure, temperature or flow − cause the entered values to be converted from the old units to the new ones. If unchecked, the values remain the same. Besides the choice of valve types, there are a wide choice of trims available for globe valves.

For liquid applications, one can select from standard, cavitation control, energy dissipating, double Z or energy dissipating (ED) disc stack. For gases, the choice is standard, low noise with one, two or three stages, and ED disc stack.

All input data and calcu-lated results are printed out along with a graph showing the control position at all the specified conditions, of which there are a maximum of nine.
For the actuator selection, the operator has to specify whether the actuator should be double-acting, spring-to-open or spring-to-close. The operator must input the air supply pressure. The programme then selects the smallest actuator that satisfies the conditions and draws force graphs for both the opening and closing positions in both directions.

The programme is available free to all PSV Mitech’s exist-ing and potential customers; however, the company recom-mends that all users attend their intermediate control valve training course.