Differential Pressure Measurement Calculator

Differential pressure measurement calculator

Find the differential pressure using the flow coefficient and other parameters with the differential pressure measurement calculator.

What is Differential Pressure?

Consider a pipe filled with fluid. The pressure may be different at all points in this pipe, especially if the pipe's width changes or if there's a pump along the path.

Differential pressure, often symbolized as ΔP is a term that describes the pressure difference that exists between two points within a fluid system. 

This difference in pressure drives fluid flow from areas of high pressure to lower pressure, following the path of least resistance. Common units of measuring pressure are pascals (Pa) or pounds per square inch (psi).

Differential pressure formula:

p = (k * W²) / (1.59923 * d² * ρ)

This formula is a derivation of the general flow formula, often used to calculate the flow coefficient (k). In this equation:

• p is the differential pressure
• k is the flow coefficient
• W is the flow rate
• d is the diameter of the pipe
• ρ is the density of the fluid

How to calculate differential pressure?

Suppose a pipe with a diameter of 0.5 m, carrying water (density of approximately 1000 kg/m³) at a flow rate of 3 m³/s. Find the differential pressure if the flow coefficient (k) is found to be 0.0297.

Solution

Flow rate (W) = 3m³/s

Diameter (d) = 0.5m

Density (ρ) = 1000kgm-3

Flow coefficient (k) = 0.0297

The formula is:

p = (k * W²) / (1.59923 * d² * ρ)

Substituting the values in:

p = (0.0297 * (3m³/s)²) / (1.59923 * (0.5m)² * 1000kg/m³)

p ≈ 2000 Pa

Real-world Applications of Differential Pressure

Flow Measurement:

The most common application of differential pressure is to measure the flow rate of a fluid in a pipe. As fluid flows through a constriction (like a venturi meter or orifice plate), the change in pressure across the constriction can be measured and used to calculate the fluid's velocity and flow rate.

Level Measurement:

Differential pressure can also be used to measure the level of a liquid in a tank. By measuring the pressure difference between the bottom and top of the tank, one can calculate the height of the liquid.

Filter Monitoring:

In air handling systems and water treatment plants, differential pressure is used to monitor the condition of filters. As a filter becomes clogged, the pressure drop across the filter increases. By monitoring this pressure drop, operators can determine when a filter needs to be replaced.

Industrial Processes:

Differential pressure is key in many industrial processes, from oil refining to food and beverage production. It helps in maintaining flow rates, monitoring filters, and controlling liquid levels.