Orifice Flow Calculator

The orifice flow calculator estimates the flow rate of liquid discharged from a tank through an orifice. In plain and simple terms, the orifice is a hole or a cutout, using which one can control or restrict the flow rate.

An orifice meter measures and controls the mass flow rate through an orifice for liquids in a tank and is extensively used in fluid mechanics allied applications such as hydraulic equipment, compressors, water tanks, sewage, weirs, and spillways. Orifices are also used to create pressure differentials in a flow.

Read on to understand how this calculator assists you in determining the mass flow through an orifice.

An orifice is a plate with a hole or cutout attached to the outlet or inserted inside a pipe such that the flow passes through the orifice. The orifice, usually circular, is of known diameter and area to keep the flow regulated. As the fluid flows through an orifice, the pressure drops across the pipe. This phenomenon is also used to measure fluid characteristics.

Mathematically, the orifice flow equation gives the mass flow rate (or discharge) $Q$ through an orifice, given the area of the orifice, $A$, and can be written as:

where $C_d$ is the coefficient of discharge, $g$ is the acceleration due to the specific gravity of Earth (in $\text{m/s}^{2}$), and $H$ is the mean center line (the distance between the water level and the center of the orifice).

The coefficient of discharge, $C_d$, is a function of various parameters such as the diameter of the orifice, $d$, as well as the acceleration due to gravity, the hydraulic depth, and the kinematic viscosity of the fluid, $\nu$. Mathematically, it can be expressed as:

To estimate the orifice flow rate, use the orifice equation discussed above:

1. Insert the diameter of the orifice, $d$.

2. The calculator will now calculate the area of orifice, $A$.

3. Enter the coefficient of discharge, $C_d$.

4. Enter the value of the mean center line, $H$

5. The acceleration due to gravity, $g$, is already filled in as $9.81\ \text{m/s}^2$ for your convenience. It can be modified by clicking on the heading "Gravitational acceleration" at the bottom of the calculator.

6. The orifice flow calculator will now return the value of discharge or orifice flow rate, $Q$.

Determine the flow rate through an orifice that has a diameter of $50 \text{ mm}$ and a mean center line of $200 \text{ mm}$. Take the coefficient of discharge, $C_d$ as $0.8$.

To estimate the orifice flow rate:

1. Insert the diameter of the orifice, $d = 50 \text{ mm}$.

2. The calculator will now estimate the area of the orifice, $A$.

3. Enter the coefficient of discharge, $C_d = 0.8$.

4. Enter the value of the mean center line, $H = 200 \text{ mm}$.

5. The acceleration due to gravity, $g$, is $9.81\text{ m/s}^2$.

6. Using the orifice equation: