Sizing Prep

The vendor tool gives the number. You have to know if it is right.

Final sizing of control valves, on/off valves and flow meters happens in vendor software (E+H Applicator, Fisher Specification Manager and others). They hold the tested coefficients. You still decide what goes in and whether what comes out makes sense: Will it cavitate? Is it too loud? Is the pressure drop worth it? Will the meter read at minimum flow? This app teaches that judgment. Every answer explains itself; wrong answers come back until they stick.

What happens in a sizing run, in 8 steps

The same chain for a control valve, an on/off valve or a meter. The Toolbox labs let you run steps 3–7 yourself.

1. Collect the casesMinimum, normal, maximum flow; P1, P2, T for each; start-up and upsets.
2. Collect the fluidDensity, viscosity, vapour and critical pressure; for gases M, γ, Z.
3. Required capacityCv or Kv per case; meter velocity and Reynolds per size.
4. LimitsChoked flow, cavitation (σ), flashing; gas choking at Fγ·xT.
5. Pick size and trimTravel 10–90% across cases; meter in its velocity window.
6. Noise and velocity85 dBA at 1 m, outlet Mach, trim exit energy.
7. Actuator and shutoffTorque or thrust at minimum air, fail position, leakage class, stroke time.
8. Review the reportRead every case, question every warning, then fill the data sheet.

How to use this

1. Study a domain's notes. Start with Fluids, then Cv sizing, Cavitation and Flow meters.
2. Practice daily. Missed questions return the same day; known ones space out to 35 days.
3. Drill the calculations: Kv/Cv, choked ΔP, σ, travel, DP scaling, surge, actuator torque.
4. Labs: size a valve across three cases, watch authority bend a characteristic, screen flow meters, and check an on/off valve for surge.

For learning only, not for design. Valve coefficients (FL, xT, rated Cv) are typical values; real ones come from the vendor for the exact trim. Equations follow IEC 60534-2-1 without piping-geometry or viscosity corrections. Progress stays in this browser.