SCFH to PSI Calculator

Calculator Inputs

Example Data Table

Formula Used

SCFH cannot be converted to PSI by a fixed factor. SCFH is a gas flow rate. PSI is pressure. A pressure estimate needs flow, gas properties, temperature, downstream pressure, and a restriction value such as Cv.

Gas flow equation:

Q = 1360 × Cv × Y × √((ΔP × P1) / (G × T))

Rearranged pressure equation:

K = (Q / (1360 × Cv × Y))² × G × T

P1 = (P2 + √(P2² + 4K)) / 2

Q is flow in SCFH. Cv is flow coefficient. Y is expansion factor. G is gas specific gravity. T is gas temperature in Rankine. P1 is inlet absolute pressure. P2 is downstream absolute pressure. ΔP is pressure drop in PSI.

Actual downstream flow:

ACFM = SCFM × (standard pressure / actual pressure) × (actual temperature / standard temperature)

Velocity:

Velocity = ACFM / pipe area

How to Use This Calculator

1. Enter the gas flow in SCFH.
2. Enter the Cv value for the valve, regulator, or restriction.
3. Add the opening percentage if the valve is not fully open.
4. Enter gas specific gravity. Use 1 for air.
5. Enter downstream gauge pressure in psig.
6. Enter gas temperature and standard condition values.
7. Add pipe inside diameter for velocity estimation.
8. Press calculate to view pressure, drop, velocity, and warning notes.
9. Download CSV for spreadsheet use.
10. Download PDF for a saved report.

SCFH to PSI Conversion Guide

SCFH describes a standard gas volume moving each hour. PSI describes pressure. They are not direct units of the same property. A useful estimate needs a restriction, gas condition, and downstream pressure. This calculator uses those values to estimate the inlet pressure needed for a selected flow. It is designed for planning, troubleshooting, and quick comparisons.

Why Inputs Matter

A gas line behaves differently as pressure, temperature, and gas gravity change. A higher flow needs more pressure across the valve or restriction. A larger Cv passes more gas with less pressure drop. Warmer gas is less dense, so the same standard flow may need a different pressure. Gas gravity adjusts the estimate for gases lighter or heavier than air.

Practical Use

Start with the measured or target SCFH. Enter the Cv for the valve, regulator, or fitting. Add downstream gauge pressure. Set gas temperature and local atmospheric pressure. Use line inside diameter when velocity matters. The result shows estimated inlet pressure, pressure drop, recommended pressure with safety margin, and downstream velocity.

Planning Notes

The calculation is a simplified compressible gas estimate. It works best for early sizing and moderate pressure drops. It does not replace manufacturer valve sizing, certified regulator charts, or licensed engineering review. Choked flow, two phase flow, severe turbulence, pulsation, leaks, and non ideal gases can change the real pressure. Always check the warning ratio and compare the answer with field measurements.

Conversion Workflow

Use the example table before entering real data. It shows typical combinations of flow, Cv, and downstream pressure. After calculation, download the CSV for spreadsheets. Use the PDF button for a simple record. Keep each saved result with gas name, temperature, equipment tag, and date. This makes later checks easier.

Best Practices

Use absolute pressure internally, even when the screen accepts gauge pressure. Confirm whether your flow value is truly standard cubic feet per hour. Standard conditions vary between industries. Match the standard temperature and pressure used by your meter or supplier. For critical work, add a safety margin, then verify the final pressure with a reliable gauge and proper operating procedure. Record each assumption so future users can repeat the same conversion without guessing during audits later.

FAQs