Agilent Pressure Flow Calculator

Pressure Flow Equation:

\[ Flow = \frac{Pressure\ Drop \times \pi \times r^4}{8 \times Viscosity \times L} \]

Pressure Drop (ΔP):

psi

Radius (r):

Viscosity:

Length (L):

Flow Rate:

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1. What is the Pressure Flow Equation?

The Pressure Flow Equation (Hagen-Poiseuille equation) calculates the volumetric flow rate of a fluid through a cylindrical pipe. It's widely used in chromatography systems like Agilent to determine flow characteristics under different pressure conditions.

2. How Does the Calculator Work?

The calculator uses the Hagen-Poiseuille equation:

\[ Flow = \frac{\Delta P \times \pi \times r^4}{8 \times \eta \times L} \]

Where:

\( \Delta P \) — Pressure drop (psi)
\( r \) — Inner radius of the tube (mm)
\( \eta \) — Dynamic viscosity (cP)
\( L \) — Length of the tube (m)

Explanation: The equation shows that flow rate is directly proportional to the pressure gradient and the fourth power of the radius, and inversely proportional to viscosity and length.

3. Importance of Flow Rate Calculation

Details: Accurate flow rate calculation is essential for optimizing chromatography systems, ensuring proper solvent delivery, and maintaining column performance in HPLC systems.

4. Using the Calculator

Tips: Enter pressure drop in psi, radius in mm, viscosity in cP, and length in meters. All values must be positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: What units does this calculator use?
A: The calculator uses psi for pressure, mm for radius, cP for viscosity, and meters for length, with output in mL/min.

Q2: What's the typical flow rate range for HPLC?
A: Most HPLC systems operate between 0.1-10 mL/min, depending on column dimensions and application requirements.

Q3: How does temperature affect the calculation?
A: Temperature affects viscosity. Use viscosity values measured at your operating temperature for accurate results.

Q4: Can this be used for gas flow?
A: No, this equation is for laminar flow of incompressible Newtonian fluids. Different equations apply for gases.

Q5: What's the maximum pressure this applies to?
A: The equation is valid for laminar flow (Re < 2100). At higher pressures/flow rates, turbulence may occur.