Here's why:
* SCFH is a volumetric flow rate at standard conditions. Standard conditions are typically defined as 0°C (32°F) and 1 atm (14.7 psi) pressure.
* Gas volumes change with temperature and pressure. As temperature increases, gas expands. As pressure increases, gas compresses.
To convert SCFH to liters, you need to know the actual temperature and pressure of the gas:
1. Calculate the volume at standard conditions: Use the ideal gas law (PV = nRT) to calculate the volume of gas at standard conditions (0°C and 1 atm).
2. Adjust for actual conditions: Use the appropriate conversion factors to adjust the volume calculated in step 1 to the actual temperature and pressure of the gas.
Example:
Let's say you have a gas flow rate of 10 SCFH, and you want to know the equivalent flow rate in liters per minute at 20°C and 1.5 atm.
1. Calculate volume at standard conditions:
* 10 SCFH = 10 ft³/hr
* 1 ft³ = 28.317 L
* 1 hr = 60 min
* Therefore, 10 SCFH = 10 ft³/hr * 28.317 L/ft³ * (1 hr/60 min) = 47.195 L/min at standard conditions.
2. Adjust for actual conditions:
* Use the combined gas law (P₁V₁/T₁ = P₂V₂/T₂) to adjust for temperature and pressure.
* P₁ = 1 atm, V₁ = 47.195 L/min, T₁ = 273 K (0°C)
* P₂ = 1.5 atm, T₂ = 293 K (20°C)
* Solving for V₂ (volume at 20°C and 1.5 atm):
* V₂ = (P₁V₁T₂)/(P₂T₁) = (1 atm * 47.195 L/min * 293 K) / (1.5 atm * 273 K) = 32.24 L/min
Therefore, 10 SCFH at 20°C and 1.5 atm is equivalent to approximately 32.24 liters per minute.
Important: Always check the specific standard conditions used in your application, as they may vary.
