LB/HR to SCFM Calculator

Convert mass flow rate (LB/HR) to volumetric flow rate (SCFM) for accurate gas flow calculations in HVAC, compressors, and process engineering.

Industrial Calculator:

Convert between mass and volumetric gas flow rates with automatic gas property adjustments and standard condition corrections.

Gas Flow Converter

Conversion Direction

Mass flow rate of the gas

Select gas type or choose custom for manual molecular weight

Standard conditions for SCFM calculations

Flow Results

Enter values and click "Convert"

to calculate gas flow

LB/HR to SCFM Gas Flow Conversion

Gas flow rates can be measured in two fundamentally different ways: by mass (like pounds per hour) or by volume (like cubic feet per minute). Converting between these measurements requires accounting for gas properties, temperature, and pressure because gases expand and contract based on these conditions.

SCFM (Standard Cubic Feet per Minute) represents gas volume at standard conditions, while LB/HR (pounds per hour) represents gas mass. The conversion depends on the gas's molecular weight and the standard conditions used for the calculation.

Why Gas Properties Matter

Different gases have different molecular weights, which directly affects how much volume they occupy for the same mass. For example, carbon dioxide is heavier than air and will produce less SCFM than air for the same LB/HR flow rate.

  • Molecular weight: Determines gas density and volume relationships
  • Standard conditions: Temperature and pressure affect gas expansion
  • Gas composition: Pure gases vs. gas mixtures
  • Measurement accuracy: Proper conversions prevent equipment sizing errors

Gas Flow Conversion Formulas

The calculator uses standard engineering formulas for gas flow conversions:

Standard Conditions Formula:
SCFM = (LB/HR × 379.48) ÷ (Molecular Weight × 60)
*For 60°F and 14.7 psi standard conditions
General Gas Law Formula:
SCFM = (Mass Flow × R × Tstd) ÷ (Pstd × Molecular Weight)
*R = Universal gas constant, Tstd/Pstd = standard conditions
Reverse Calculation:
LB/HR = (SCFM × Molecular Weight × 60) ÷ 379.48
*Converts from volumetric to mass flow

All calculations automatically account for unit conversions and standard condition adjustments.

Gas Flow Conversion Examples

Here are common gas flow conversions used in industrial applications:

Mass Flow (LB/HR) Gas Type Molecular Weight SCFM Result Application
100 Air 28.97 21.8 HVAC system
200 Nitrogen 28.01 45.0 Food packaging
150 Oxygen 32.00 29.5 Medical oxygen
300 CO₂ 44.01 43.0 Beverage carbonation
50 Natural Gas 16.04 19.7 Gas appliance
400 Air 28.97 87.3 Large compressor
75 Nitrogen 28.01 16.9 Laser cutting
250 Oxygen 32.00 49.2 Welding system
85 Air 28.97 18.5 Paint booth ventilation
120 CO₂ 44.01 17.2 Greenhouse enrichment
65 Natural Gas 16.04 25.6 Water heater
180 Nitrogen 28.01 40.6 Tire inflation system
95 Oxygen 32.00 18.7 Fish tank aeration
350 Air 28.97 76.2 Industrial dust collector
45 CO₂ 44.01 6.4 Dry ice production
160 Natural Gas 16.04 63.0 Commercial oven
220 Nitrogen 28.01 49.6 Chemical blanketing
110 Oxygen 32.00 21.7 Ozone generator
275 Air 28.97 59.9 Spray paint booth
135 CO₂ 44.01 19.4 Aquarium pH control
90 Natural Gas 16.04 35.4 BBQ grill
195 Nitrogen 28.01 44.0 Plasma cutter
125 Oxygen 32.00 24.6 Metal cutting torch
320 Air 28.97 69.7 Sandblasting cabinet
55 CO₂ 44.01 7.9 Keg carbonation
140 Natural Gas 16.04 55.1 Gas fireplace
175 Nitrogen 28.01 39.5 Wine preservation
80 Oxygen 32.00 15.7 Respiratory therapy
Engineering Note:

Gas flow calculations should be verified with calibrated instrumentation. Standard conditions vary by industry, so confirm the appropriate standards for your specific application.