## Difference between venturi meter and orifice meter

Flow is one of the crucial process variables that is needed to be measured, transmitted, manipulated, and controlled in order to ensure the safety and success of a given process in process control industries.
Orifice plates and venturi meters are the two most widely used flow meters in industries for flow measurement.

In this article, the orifice meters and centimeters are compared and their similarities and differences are listed.

Similarities

1. Orifice plates and venturi meters come under the category of Variable head flow meters Differential flow meters or Obstruction type meters. They are the Primary elements of a differential flow meter. The primary elements are placed in the path of the fluid and introduce an obstruction to the fluid passage in order to produce a differential pressure.

2. Orifice plates and venturi meters are used in conjunction with secondary elements of differential flow meters. Secondary elements are differential pressure measuring devices namely, manometer, bellow meter, force balance meter, and ring balance meter.

3. Orifice plates and venturi meters are called as volumetric flow detectors as they measure the volume of the flow rate. Mass flow rates can be calculated by measuring temperature and pressure.

4. Orifice plates and venturi meters work on Bernoulli’s principle which states that the difference in pressure created across the obstruction gives the measure of the fluid flow rate. The flow rate is proportional to the square root of the differential pressure.

5. It is difficult to employ these meters to measure pulsating flow.

Differences between orifice plate and venturi meter

* The turndown ratio gives an idea about the range in which the particular flow meter can be operated with the desired accuracy.

Turndown ratio can be expressed as:

TR = qmax / qmin

Where,

TR = Turndown Ratio

max = maximum flow

qmin = minimum flow