This document discusses types of orifices used for fluid flow measurement. Orifices can be classified based on their shape (circular, triangular, etc.), size (small or large), edge shape (sharp or bell-mouthed), and whether the flow is submerged or free-flowing. Orifice meters consist of a flat plate with a circular hole and are used to measure flow rates in pipes. They offer little pressure drop but require straight pipe runs and full pipeline filling to maintain accuracy. Mouthpieces are also used for flow measurement and can be internal or external, and classified based on their shape (cylindrical, convergent, convergent-divergent) and whether the flow exits fully or

2. Name:-PRAJAPATI TIRATH A.
• BRANCH:-CIVIL (B)
• ENROLLMENT NO:-151240106066
• SUBJECT:-FLUID MECHANICS(2130602)
• TOPIC:-ORIFICE TYPES
• Guided by:- VIKRAM PANCHAL

3. ORIFICE
 Orifice is a small opening of any cross-section (such as
circular, triangular, rectangular, etc.) on the side or at the bottom
of a tank, through which a fluid is flowing.
 The orifice is used to measure discharge. An orifice is
provided in verticle side of the tank or in the base.

4. Classification of orifices:
1). According to shape of orifice
2). According to size of orifice
3). According to Shape of edge
4). According to Nature of discharge
The sub-merged orifices are further classified as
a). Fully sub-merged orifices
b). Partially sub-merged orifices

5. 1). The orifices are classified as small orifice or
large orifice depending upon the size of orifice and
head of liquid from the centre of the orifice.
If the head of the liquid from the centre of
orifice is more than five times the depth of the
orifice, the orifice is called small orifice.
And if the head of the liquid is less than five
times the depth of orifice , it is known as large
orifice.
2). On the basis of their cross-sectional areas they
are classified as
 Circular orifice
Triangular orifice
Rectangular orifice
Square orifice

6. SUBMERGED ORIFICE
• A submerged orifice and the same orifice discharging freely have nearly the same
coefficient of discharge.
• Submerging an orifice provides the capability to measure relatively large flows
with a small drop in water surface, conserving delivery head compared with
weirs.
• However, the submerged orifice requires head measurements upstream and
downstream.

7. 3). Depending upon the nature of discharge, orifices are
classified as
 Free discharging orifices
Fully drowned orifices
Partially drowned orifice
4).Depending upon the shape of upstream edge of the
orifices, they are classified as
 Sharp-edged orifices
 Bell-mouthed orifices

8. Working
Orifice meter is device used to determine the rate of flow through pipe.
It consist of flat circular plate which has a sharp edged circular hole called
orifice.
It is fixed concentric to pipe.
The orifice diameter is generally kept half of the diameter of the pipe.
It is based on the same principle as explained in venturimeter.
The value of Cd varies between 0.60 to 0.65.
It is a economical and less space is required for fitting.

9. Advantages of orifice meter
• Orifices are small plates and easy to install/remove.
• Offer very little pressure drop of which 60% to 65% is recovered.
• Orifice meter can be easily maintained.
• Measures a wide range of flow rates.
• They have a simple construction.
• They have easily fitted between flanges.
• They are most suitable for most gases and liquids.
• They are inexpensive.
• Price does not increase dramatically with size.

10. Disadvantages of orifice meter
• Requires homogeneous fluid.
• Requires single phase liquid.
• Requires axial velocity vector flow.
• Causes a pressure drop in fluid.
• Their accuracy is affected by density , pressure and viscosity fluid.
• Fluid viscosity limits measuring range.
• Requires straight pipe runs to ensure accuracy is maintained.
• Pipe line must be fully especially for liquid flow measurement.
• They have low range-ability.

11. MOUTHPIECES
A mouthpiece is a short length of a pipe which is two or three times its diameter in length, fitted in a tank or
vessel containing the fluid.
It is used for measuring the rate of flow of liquid.
Classification of mouthpieces:
1). Depending upon their position with respect to the tank they are classified as
 External mouthpieces
 Internal mouthpieces

12. 2). Depending upon their shape they are classified as
 Cylindrical mouthpieces
 Convergent mouthpieces
 Convergent-divergent mouthpieces
3). Depending upon the nature of discharge at the
outlet of mouthpiece they are classified as
 Mouthpieces running full
 Mouthpieces running free
A mouthpiece is said to be running free if the jet of the liquid after contraction does
not touch the sides of mouthpiece .
But if the jet after contraction expands and fills the whole mouthpiece it is known as
running full.