The Liquid Valve Sizing Kit
The ValveTool kit for finding the pressure drop a control valve really gets, and sizing it to pass the most flow and still control the least
Our Valve Sizing and Valve Cv calculators take the allowable pressure drop as a number you already have, and size at a single flow. No tool on the site works out what the pump actually leaves the valve after the pipe and equipment, or checks the valve at minimum flow, where it takes the most drop, or whether the liquid chokes. The kit builds the valve's pressure budget. In the worked cooling-water loop the pump gives 22 psi at 200 gpm; typed in as the allowable drop, that shortlists a Cv 55 valve. Pipe and an exchanger take 11.87 psi first, so the valve really gets 10.13 psi, where a Cv 55 valve passes only 175.1 gpm wide open. Sized from what is left it needs Cv 62.84 and a Cv 90 valve, which the minimum flow still uses 11.1% of; run hot at a lower inlet pressure, the same drop chokes. The figures are examples, computed by the site's own calculators and standard formulas (Darcy-Weisbach, the IEC 60534-2-1 liquid choked-flow limit); your pump curve and data sheets replace them. Liquid service only: relief and safety valves, steam, gases, flammable or toxic fluids and code-governed duties go to the manufacturer's sizing software and a qualified engineer. Included: 24 printable pages with seven steps, four working pages and reference tables, plus a personalised sheet worked from the numbers you entered in the calculator you came from.
Look inside
Two full pages from the kit, exactly as printed. Click either to read it at full size before you decide.
What is in it
- One unit for every sheet, and what a metric flow typed into a gpm box does to a Cv
- Maximum, normal and minimum flow, with the pipe velocity and Reynolds number at each
- Pipe and fitting friction by Darcy-Weisbach, and every exchanger, filter and meter scaled with the square of flow
- The valve's allowable drop worked out from the pump curve, and why the pump's pressure is not it
- Cv and Kv at three flows, checked against the 80 and 10 percent rules of thumb
- A choked-flow screen with FL, vapor pressure and the cavitation index to hand the maker
- The spec sheet the maker sizes from, and the questions only the maker and an engineer can close
- A duty sheet, a pressure budget, a valve check and a spec sheet to print
- Reference tables: velocity and friction in Schedule 40 pipe, water vapor pressure, unit conversions
- A personalised sheet: your Cv, the rated valve with its headroom, and the drop the valve really gets, from the calculator you used
- ✓ 24 printable pages
- ✓ 10 sections, worksheets and templates
- ✓ A second PDF worked out from the numbers you enter
- ✓ No account needed, just an email address
- ✓ Instant download; link valid 7 days
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The kit picks up where the free Valve Sizing Calculatorleaves off. The calculator takes the allowable pressure drop as a number you already have and sizes at one flow; the kit works that drop out from your pump curve, pipe and equipment at maximum, normal and minimum flow, checks the valve at both ends of its range, and screens the largest drop for choked flow. The worked figures are examples; your own curves and data sheets replace them. It is for liquid service only: relief and safety valves, steam, gases, flammable or toxic fluids and any code-governed duty belong with the manufacturer’s sizing software and a qualified engineer.