Orifice-meter

Orifice-meter is a hydraulic measuring instrument used to control the speed of the water or fluid flowing through the various types of pipe. Let’s discuss this instrument’s working principle in detail.

Construction: Orifice-meter comprises four parts namely, inlet suction, orifice plate, flow conditioner, and outlet section. The inlet section through which fluid inflows into orifice-meter and outflows through outlet section. The thin-sized plate called an orifice plate contains few holes through which fluid will pass and there is a pressure drop in fluid flow. The system attached a flow conditioner which increases the flow through inlet section.

WORKING: The orifice plate is used to give resistance to the fluid flow which results in the pressure drop in the flowing fluid. The working principle of orifice-meter is the phenomenon of Bernoulli’s theorem. The drop in pressure can be measured by a differential manometer. The length of Orifice would be within the range of 10–800 mm and diameter of Orifice plate may be within the range of 0.4 to 0.8 times the diameter of the pipe. The pressure of fluid within the system can be maximum of up to 400 Bar.

APPLICATIONS: Few major applications as mention below:

1. It is used in Engine Carburetors to measure airflow relevant in automobile industry.
2. It is commonly used in process industries to control flow rate.
3. It is also used in medical industry as blood flows in the arteries measured by this.
4. The flow rate of oil and gasoline taken by Orifice-meter in Oil & Gas Industries.

ADVANTAGES: The Orifice-meter is widely used in many industries because of following advantages as

1. The foremost advantage of this is very cheaply available as compared to the Orifice-meter.
2. The space required for installation is less.
3. This system provides very less pressure drop.
4. The system is capable to use for a variety of fluids.
5. Its maintenance cost is very low.
6. The system can be placed in preferred positions whether it can be vertical, horizontal, or inclined at a certain angle.
7. The orifice plate is so thin that it fitted in between the existing pipe.

DISADVANTAGES: However, there are certain limitations such as:

1. Due to the low cross-sectional area of orifice plate, sometimes it is difficult to read the pressure drop.
2. Here, downstream pressure can not be measured.
3. The accuracy in reading by Orifice-meter is greatly affected by viscosity, density, and pressure of the fluid.
4. Here, the coefficient of discharge is very low as compared to the venturi-meter. The system is suitable in straight pipe usually

SUGGESTED BOOK FOR REFERENCE

FLUID KINEMATICS with Bernoulli's Equation: FUNDAMENTALS AND APPLICATIONS