DP Level & Flow
What this tool does
Liquid and gas Cv with a choked-flow flag. This page says what the tool is for, in plain language. The working formula stays on the signed-in tool.
When to use it
Open Control valve Cv when this is the job: Liquid and gas Cv with a choked-flow flag. That is usually a level or flow calibration, a bore check, or a valve you are about to size.
Step-by-step
- Open Control valve Cv from the tool list.
- Fill Fluid, Units, Flow, Flow span from the instrument, the drawing, or the job record. Use the unit shown beside each field.
- Fill the remaining fields the same way. Skip a field only when the screen marks it optional.
- Run Calculate when that control is on the page, then read every result row and any warning.
- Check the result against the site procedure and the manufacturer data before you change a range, a wire, a setpoint, or a weight.
- This help page is public. Opening the tool still requires a Pro session.
Inputs
- Fluid
- Choose the Fluid that matches the instrument, the drawing, or the job. Choices include Liquid, Gas.
- Units
- Imperial or metric. Pick one and enter every other field in that system.
- Flow
- Flow is the value you read from the instrument, the drawing, or the job record. Enter it in gpm.
- Flow span
- Flow span is the value you read from the instrument, the drawing, or the job record.
- Pressure drop
- Pressure drop is the value you read from the instrument, the drawing, or the job record. Enter it in psi.
- Upstream absolute pressure
- Upstream absolute pressure is the value you read from the instrument, the drawing, or the job record. Enter it in psia.
- Liquid specific gravity
- Liquid specific gravity is the value you read from the instrument, the drawing, or the job record.
- Vapor pressure
- Vapor pressure is the value you read from the instrument, the drawing, or the job record. Enter it in psia.
- Critical pressure
- Critical pressure is the value you read from the instrument, the drawing, or the job record. Enter it in psia.
- Fl
- Fl is the value you read from the instrument, the drawing, or the job record.
- Gas specific gravity
- Gas specific gravity is the value you read from the instrument, the drawing, or the job record.
- Temperature
- Temperature is the value you read from the instrument, the drawing, or the job record. Enter it in °F.
- Specific-heat ratio
- Specific-heat ratio is the value you read from the instrument, the drawing, or the job record.
- xT
- xT is the value you read from the instrument, the drawing, or the job record.
- Compressibility
- Compressibility is the value you read from the instrument, the drawing, or the job record.
Results
- Result
- The reported value for Control valve Cv. Use the unit printed on that row.
- Warnings
- A warning means an entry is incomplete or outside what this tool will stand behind. Recheck the inputs and the site procedure.
Common mistakes
- Using the wrong specific gravity, or forgetting a wet leg, a seal fill, or a blanket pressure.
- Mixing a head unit with a pressure unit without reading the unit on the screen.
- Sizing from a flow or a differential that is not the one in the line.
- Do not treat a result from Control valve Cv as a substitute for the site procedure or the manufacturer data.
Standards references
These are the standards and public references named on this tool. Clause numbers appear only when the catalog already cites them.
- IEC 60534-2-1 sizing equations for incompressible and compressible flow
- ISA-75.01 control-valve sizing equations
- IEC 60534-1 Cv to Kv factor 0.865
Offline and access
This engine can run offline after the server has cached it for the signed-in account.
A free session can read this help page. The tool card shows the name and the short summary. Opening the tool requires Pro.