Pressure Measurement Instruments

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Questions and Answers

What is the difference in height of water, ha-hb, expressed in meters during the pressure difference calculation?

1.280 m of water

What is the absolute pressure in the pipe expressed in meters of water, given the vacuum pressure and atmospheric pressure?

9.6 m of water

How do you calculate the pressure difference Pa-Pb in kN/m2 using the water height?

Pa-Pb = 12.556 kN/m2

If the specific gravity of liquid in pipe A is 1.5, what does that indicate about the liquid compared to water?

The liquid in pipe A is denser than water. Signup and view all the answers

What is the specific gravity of the liquid in pipe B, and what does it infer about its density?

0.85, indicating it is less dense than water. Signup and view all the answers

Given the pressure difference of 10 m of water between two pipes, what relationship does it imply when comparing the two specific gravities?

The pressure difference is influenced by the specific gravities of the liquids in both pipes. Signup and view all the answers

When using a U-tube manometer, how is the pressure in the pipeline derived from mercury levels?

By summing the heights of water equivalents from each side of the mercury. Signup and view all the answers

What do you obtain when you add atmospheric pressure to gauge pressure in kN/m2?

113.856 kN/m2 Signup and view all the answers

How can the pressure in a pipe be determined using a micro manometer?

The pressure in a pipe can be determined by using the micro manometer equation that incorporates the heights of liquid columns and the specific gravities of the liquids involved. Signup and view all the answers

What values are needed to calculate the pressure in a pipe with a liquid of specific gravity 0.8?

To calculate the pressure, you need the height of liquid in both limbs, the specific gravity of both the liquid and mercury, along with the ratio of the areas. Signup and view all the answers

What is the purpose of the Bourdons tube in mechanical gauges?

The Bourdons tube is designed to measure high pressure by deforming elastically in response to the fluid pressure, converting this deformation into a rotational movement for the pointer. Signup and view all the answers

Explain the significance of the specific weight of water in pressure calculations.

The specific weight of water is essential in pressure calculations as it provides the necessary constant used to convert height measurements of liquid columns into pressure units. Signup and view all the answers

List two advantages of using mechanical gauges for pressure measurement.

Mechanical gauges are durable and provide direct readings, making them practical for various applications. Signup and view all the answers

What is the significance of the ratio of the basin area to the limb area in a micro manometer?

The ratio of basin area to limb area affects the pressure measurement sensitivity and accuracy by influencing the liquid height differences observed. Signup and view all the answers

How does the specific gravity of liquids affect pressure readings when using a micro manometer?

The specific gravity of the liquids influences the height difference in the manometer, which is crucial for calculating the pressure difference accurately. Signup and view all the answers

Describe how the pointer movement is achieved in a Bourdons tube pressure gauge.

Pointer movement in a Bourdons tube gauge is achieved through the elastic deformation of the tube, which causes one end to move and rotates a linked pointer. Signup and view all the answers

What is the difference in mercury level for the first example given?

The difference in mercury level is 0.988 m. Signup and view all the answers

Calculate the height (h2) for the second example with fluid pressures given.

The height h2 is 0.3416 m. Signup and view all the answers

In a manometer connected to two identical pipes, what is the specific gravity given for the liquid in both pipes?

The specific gravity of the liquid in both pipes is 1.4. Signup and view all the answers

What equation relates the pressures in the two pipes in the last example?

The equation is derived from the manometer reading as ha - h1S1 = hb - h2S2 - h3S3. Signup and view all the answers

What is the calculated difference in pressure (Pa - Pb) in the last scenario?

The difference in pressure Pa - Pb is 2.178 kN/m2. Signup and view all the answers

What role does the specific gravity of the manometric liquid (0.8) play in the calculations?

It is used to relate the heights of the liquid columns to the pressure differences. Signup and view all the answers

What must be understood about the setup of the manometer to solve for pressure differences?

The heights and densities of the fluids on both sides must be balanced to determine pressure differences. Signup and view all the answers

Using the values from the second example, what is the pressure in pipe A before considering fluid heights?

The pressure in pipe A is 118 kN/m2. Signup and view all the answers

Convert a pressure head of 500 mm of mercury into oil of relative density 0.75.

9.066 m of Oil Signup and view all the answers

If a driver can sustain a pressure of 110 kN/m² under seawater, what is the maximum depth he can work at?

11.213 m Signup and view all the answers

Given a pressure of 439.49 kN/m² at a point 40m below the sea surface, what is the density of seawater?

The density of seawater is approximately 10.9 kN/m³. Signup and view all the answers

A gauge on a compressor reads 30 kN/m². What is the corresponding absolute pressure?

131.325 kN/m² Signup and view all the answers

If the measurements at the base and top of a mountain are 720 mm and 550 mm of mercury, what is the height of the mountain?

1.89 m Signup and view all the answers

What is the pressure in the pipe if a simple manometer shows a mercury level difference of 125 mm?

1.575 m of water Signup and view all the answers

Determine the absolute pressure of oil in a pipeline if the U-tube manometer shows a 0.2m mercury level difference with the pipe's center 0.1m below the mercury level.

Specific calculation required for pressure conversion. Signup and view all the answers

What is the pressure difference between two points in a horizontal venturimeter containing oil of relative density 0.8 if the mercury level deflects by 0.8m?

100.54 kN/m² Signup and view all the answers

What equation is used to calculate head loss due to friction in a pipe according to Darcy's formula?

The equation used is $h_f = f \times \frac{L}{d} \times \frac{v^2}{2g}$ where $h_f$ is the head loss. Signup and view all the answers

What is the head loss due to friction for a pipe with a diameter of 600 mm, length of 1.5 km, flow velocity of 2.5 m/s, and a friction factor of 0.02?

The head loss is 15.92 m. Signup and view all the answers

In a 200 mm diameter pipe 500 m long, with water flowing at 5 m/s and a friction factor of 0.008, what is the head loss due to friction?

The head loss is approximately 101.9368 m. Signup and view all the answers

How is discharge calculated for a pipe with a diameter of 50 mm and a head difference of 20 m between two reservoirs?

Discharge is calculated using $Q = a v$, where $a = \frac{\pi d^2}{4}$ and $v$ is determined from the head loss. Signup and view all the answers

What values are used to calculate the discharge in liters per second for a 0.5 m diameter pipe, given specific flow conditions?

The diameter, velocity $v = 1.9889 , m/s$, and the formula yields a discharge of 390.05 liters/sec. Signup and view all the answers

When comparing two pipes of different diameters but equal lengths and friction factors, how does diameter affect discharge if head loss remains constant?

The pipe with a larger diameter will have a higher discharge under the same head loss conditions. Signup and view all the answers

What is the impact of the friction factor on the head loss in a flow system?

A higher friction factor results in greater head loss for the same flow conditions. Signup and view all the answers

What is the significance of the velocity of flow in determining head loss in a pipe system?

Increased velocity leads to increased head loss, as it is squared in the head loss equation. Signup and view all the answers

Study Notes

Micro Manometer

The pressure in a pipe containing a liquid can be determined using a micro manometer.
The pressure is calculated based on the difference in height of the liquid in the two limbs of the manometer, and the specific gravity of the liquids used.

Mechanical Gauges

Mechanical gauges are direct pressure measuring instruments.
Examples of mechanical gauges include Bourdon tube pressure gauges, diaphragm pressure gauges, dead weight pressure gauges, and bellows pressure gauges.
Advantages of mechanical gauges include durability, portability, direct reading, and long life.

Bourdon Tube Pressure Gauge

The Bourdon tube pressure gauge is used for measuring high pressures.
The principle used in this gauge is the elastic deformation of a metallic tube, which is proportional to the fluid pressure.
The gauge consists of an elliptical tube, a toothed sector, links, a pinion, and a pointer.
When pressure enters the tube, it deforms, causing the free end to move outward.
The elastic deformation of the Bourdon tube rotates the pointer through the links, providing a pressure reading.

Head Loss Due to Friction

Head loss due to friction (hf) is the loss of energy in a fluid due to frictional forces acting on it as it flows through a pipe.
Darcy's formula is used to calculate head loss due to friction: hf = (4flv^2/2gd).
The head loss due to friction is dependent upon the friction factor (f), the length of the pipe (l), the velocity of the flow (v), and the diameter of the pipe (d).

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Description

This quiz explores various pressure measurement instruments including micro manometers and mechanical gauges. It covers concepts such as the working principle of Bourdon tube pressure gauges and their applications. Test your knowledge on how to determine pressure through liquid height differences and gauge mechanisms.