# Differential Pressure Calculator

The differential pressure calculator will assist you in computing the **change in pressure** across a valve or a fluid flow device in a fluid system. From a **pitot tube in an aircraft to measure airspeed (see true airspeed calculator) to a pneumatic valve in a robotic arm**, and all things in between, differential pressure in a fluid flow system play a vital role in their operations.

**Pressure switches act on the pre-set values of change in pressure** to trigger circuit breaking or make any other adjustments like opening an extra valve, redirecting the fluid flow, or detecting a blockage in the pipes or airways. Such pressure switches operate along with pressure sensors or gauges that monitor the pressure in a fluid system.

The concept is useful for **fluid flows in a pipe** regardless of the pipe's location. It could be a **respiratory medical device, flow measurement in aircraft, heating, ventilation, air conditioning (HVAC) systems, or any other hydraulic or pneumatically operating system**. The pressure differential is a **function of discharge, flow coefficient, and the specific gravity of the fluid**.

This article will explain differential pressure and how to calculate flow rate using differential pressure.

## What is differential pressure?

Consider **fluid flow through an orifice** (cf. orifice flow calculator), a venturi, or a similar constriction having a pressure gauge on either side. The **change in pressure** between the two gauges is known as differential pressure. It is helpful **to find any blockages or leaks** in the system as it will cause a change in differential pressure. Mathematically, it is related to the flow factor or flow coefficient, volumetric flow rate, and the fluid's specific gravity:

where:

- $K_v$ – Flow factor;
- $S$ – Specific gravity of the fluid (refer, specific gravity calculator);
- $Q$ – Volumetric flow rate; and
- $\Delta P$ – Differential pressure.

The flow factor is the efficiency of the fluid flow through a pipeline. It is also expressed in $\text{m}^3/\text{hr}$.

## Differential pressure calculation – Calculate flow rate from pressure differential

To calculate differential pressure:

- Enter the
**specific gravity**of the fluid or select from the**list of fluids**. - Fill in the
**volumetric flow rate**for the flow. - Insert the
**flow factor**. - The calculator will return the
**differential pressure**.

To calculate the flow rate, you can leave the field empty and enter the pressure difference instead.

## Example: Using the differential pressure calculator

Find the pressure difference if the water has a volumetric flow rate of `10 l/min`

and a flow factor of `5 l/min`

.

To calculate differential pressure:

- Enter the
**specific gravity**of water as`1`

. - Fill in the
**volumetric flow rate**for the flow as $10 \text{ l/min}$. - Insert the
**flow factor**as $5 \text{ l/min}$. - Using the differential pressure formula:

## FAQ

### What do you mean by differential pressure?

The **change in pressure when a fluid passes through a constriction like a venturi or an orifice** is the differential pressure. It has the **same units as pressure**, i.e., `bars`

or `Pa`

. It is a pressure measurement method and is very common in fluid flow systems.

### How do you calculate differential pressure?

To calculate differential pressure:

- Find the
**square**of**volumetric flow rate**. - Find the
**square**of**flow factor**. **Divide**the**square of volumetric flow rate**by the**square of flow factor**.**Multiply**the resultant with the**specific gravity of the fluid**to obtain the differential pressure.

### How do I calculate flow rate using differential pressure?

To calculate flow rate using differential pressure:

**Divide**the**pressure difference**(ΔP) by the**specific gravity**(S) of the fluid.- Find the
**square root**of the resultant division. **Multiply**the root by the**flow factor (Kv)**to obtain the**flow rate**(Q) for the fluid system. Mathematically, that's:

`Q = √(Kv² × (ΔP/S))`

### What are the applications of differential pressure?

The differential pressure is a measurement method that is used in:

- Detecting
**blockages and leaks**in the system; - Activating pressure
**switches and valves**; - Determining the proper
**functioning**of fluid flow systems; - Measuring
**liquid levels**and**flow rates**; and - Respiratory
**flow in medical devices**.