A

Seminar Report

On

RECIPROCATING PUMP WITH AIR VESSEL

Submitted by

PATIL KRUNAL R.

EN.NO. 106550319004

Of FMHM

Guided by

HIREN PATEL

(L.M.E.)

Department Of Mechanical Engineering

VALLBHBUDHI POLYTECHNIC

NAVSARI

ACKNOWLEDGEMENTI take this privileged opportunity to express our hearty thanks to you for

providing me and guiding me such a nice opportunity of learning and developing myself as better mechanical professional.

I would also like to thank Mr. HIREN PATEL (L.M.E.) for helping out me during the entire seminar procedure conducted during the semester.

I would thank to express my deep feeling of gratitude to the under mentioned faculties for their assistance, guidance and inspiration before and through the seminar. I also indebted to sir for their readiness to provide all resources for making this seminar successfully completed well within time.

I would like to thank Vallbhbudhi Polytechnic, Navsari for providing me such a good opportunity to represent the seminar.

As far as my work is concerned I have tried to make very clear the information I am providing and have tried best to represent myself in this seminar.

Thanking you,

Krunal Patil

INDEX

(Ī) ACKNOWLEDGMENT 2

Chapter 1 INTRODUCTION page no.1.1 Piston & cylinder 51.2 Suction pipe 51.3 Suction valve 51.4 Delivery pipe 51.5 Delivery valve 51.6 Strainer 61.7 Crank 61.8 Connecting rod 61.9 Air vessel 6

Chapter 2 PRINCIPLE & WORKING2.1 Principle 7 2.2 Working 7

Chapter 3 TYPES OF RECIPROCATING PUMP

3.1 Types 93.2 Piston type pump 9 A) Single acting reciprocating pump 10

B) Double acting reciprocating pump 113.3 Diaphragm pump 11

A) Hydraulic operated diaphragm pump 13B) Air actuated diaphragm pump 14

Chapter 4 AIR VESSEL

4.1 What is Air vessel? 15

4.2 Why an air vessel is fitted? 16

4.3 Purposes of Air vessel 16

4.4 Working 16

4.5 Flow into and out of Air vessel 17

Chapter 5 THEORATICAL POWER REQUIRED 18

CONCLUSION 19

1. IntroductionReciprocating pump is a positive displacement pump. Here we will study reciprocating pump with air vessel. It can be used for less discharge at higher heads. Priming is not required because it is a positive displacement pump. Reciprocating pump is used in pumping water in hilly areas. Reciprocating pumps has lower efficiency compared to centrifugal pumps.

Following are the main parts of reciprocating pump.

1. Piston and cylinder 2. Suction pipe3. Suction valve4. Delivery pipe5. Delivery valve6. Strainer 7. Crank 8. Connecting rod9. Air vessel

1) Piston and cylinder: Piston reciprocates in the cylinder. Crank shaft which is connected to motor and connecting rod give motion to piston. Main function of piston and cylinder is to pull the water in cylinder and push it at required height.

2) Suction pipe: The suction pipe’s one end is connected to the pump and other is depth in the sump. Water enters from sump in to pump through suction pipe.

3) Suction valve: The suction valve is fitted on suction pipe close to the cylinder. It allows the entry of water in to cylinder.

4) Delivery pipe: Delivery pipe is connected betⁿ pump and reservoir. Through the delivery pipe water transferred from pump to reservoir.

5) Delivery valve: The delivery valve is fitted on the delivery pipe close to the cylinder. It allows water to flow in delivery pipe from cylinder.

FIGURE 1

6) Strainer: It is used to prevent impurities and solid particles from entering the pump.

7) Crank: Crank is used to pass motor work to the piston.8) Connecting rod: It connects crank with the piston.9) Air vessel: Air vessel is used to reduce frictional head and give a steady flow

of liquid.

2. PRINCIPLE & WORKING: Fast moving air formed by releasing high pressure air through a slit

is discharged adjacent a surface, and drags surrounding air along with it. The higher the pressure of the primary air supply, the worse the efficiency

The liquid enters a pumping chamber via an inlet valve and is pushed out via an outlet valve by the action of the piston or diaphragm.

Pump is self priming as it can draw liquid from a level below the suction flange even if the suction pipe is not evacuated.

WORKING:

The working of reciprocating pump can be easily understood by above figure. When starting the pump, the suction and discharge valves must be opened. It is important that no valves in the discharge line are closed, otherwise either the relief valve will lift or damage may occur to the pump when it is started.

The pump is self priming, but where possible to reduce wear or the risk of seizure it should be flooded with liquid before starting. An electrically driven pump only needs to be switched on, when it will run erratically for a short period

FIGURE 2

until liquid is drawn into the pump. A steam driven pump will require the usual draining and warming through procedure before the steam is gradually admitted.

These pumps deliver a highly pulsed flow. If a smooth flow is required then the discharge flow system has to include additional features such as accumulators. An automatic relief valve set at a safe pressure is used on the discharge side of all positive displacement pumps.

The performance of a pump is characterized by its net head h, which is defined as the change in Bernoulli head between the suction side and the delivery side of the pump. H is expressed in equivalent column height of water.

3. TYPES OF RECIPROCATING PUMP:There are main two types of reciprocating pump:

a) Piston pumpb) Diaphragm pump

The other types of reciprocating pump are as below:

1) According to the action of water:a. Single acting.b. Double acting.

2) According to the number of cylinders:a. Single cylinder.b. Double cylinder.c. Triple cylinder.

3) According to the existence of air vessel:a. With air vessel.b. Without vessel.

Piston type pump: A piston pump can be based on a single piston or, more likely, multiple

parallel pistons. The pistons are reciprocated using cams or crankshafts. The stroke is generally adjustable. This type of pump can deliver heads of up to 1000 bar. The largest sizes of piston pumps can deliver flows of 40m3 /hr. In practice these pumps are more likely to be used for metering low flow rate fluids at more modest pressures in laboratories and chemical process plants. Piston pumps are not generally suitable for transferring toxic or explosive media.

There are two types of piston pump:

a) Single acting reciprocating pumpb) Double acting reciprocating pump.

A) Single Acting Reciprocating pump:

Figure 1 is a typical layout of single-acting piston pump. The power end, which consists of the crankshaft, connecting rod(s), crosshead(s) and other components, is to the right. The liquid end, including the suction and discharge manifolds, piston(s) and cylinder(s), suction and discharge check valves and the fluid chamber, is to the left.

Its operation is similar to other piston machines (engines, compressors, etc). During the suction stroke the upper discharge check valve closes and allows the piston to draw fluid into the cylinder through the lower suction valve. When the piston changes direction (reciprocates), the suction valve closes and the fluid is forced out of the cylinder through the discharge valve. Like other piston-based machines, the sealing rings move with the piston. Some piston pumps use a different valve design that allows water to enter the rear of the cylinder during the discharge stroke. During the back stroke it is transferred to the front side of the piston via a check valve and is forced out during the discharge stroke. The single acting pump discharges water only on its forward stroke.

FIGURE 3

B) Double Acting Reciprocating Pump:

A more complex design, known as the double-acting pump, allows the piston to discharge fluid during both its forward and back stroke, resulting in almost twice the flow per cycle.

Figure 2 is a typical layout of a plunger pump. The power end is similar to the one seen in Figure 1 but there are two distinct differences in the liquid end. The piston is replaced with a plunger that is sealed by stationary sealing rings (A). Also, there is no cylinder-just a fluid chamber between the check valves. Plunger pumps operate on the principle that a solid will displace a volume of liquid equal to its own volume. Instead of forcing the liquid out of a cylinder via a piston, the plunger enters the fluid chamber and displaces an amount of liquid equal to the plunger volume entering the chamber.

Diaphragm pump: A diaphragm pump is a positive displacement pump that uses a

combination of the reciprocating action of a rubber, thermoplastic or Teflon diaphragm and suitable non-return check valve to pump a fluid. Sometimes this type of pump is also called a membrane pump.

FIGURE 4

There are three main types of diaphragm pumps:

Those in which the diaphragm is sealed with one side in the fluid to be pumped, and the other in air or hydraulic fluid. The diaphragm is flexed, causing the volume of the pump chamber to increase and decrease. A pair of non-return check valve prevents reverse flow of the fluid.

Those employing volumetric positive displacement where the prime mover of the diaphragm is electro-mechanical, working through a crank or geared motor drive. This method flexes the diaphragm through simple mechanical action, and one side of the diaphragm is open to air.

Those employing one or more unsealed diaphragms with the fluid to be pumped on both sides. The diaphragm(s) again are flexed, causing the volume to change.

When the volume of a chamber of either type of pump is increased (the diaphragm moving up), the pressure decreases, and fluid is drawn into the chamber. When the chamber pressure later increases from decreased volume (the diaphragm moving down), the fluid previously drawn in is forced out. Finally, the diaphragm moving up once again draws fluid into the chamber, completing the cycle. This action is similar to that of the cylinder in an IC engine.

FIGURE 5

There are two types of diaphragm pump:a) Hydraulic operated diaphragm metering pumpb) Air actuated diaphragm pump

Hydraulic operated diaphragm metering pump:

FIGURE 6

Air actuated diaphragm pump:

Air operated diaphragm pumps (AOD) or Air-Driven Pumps are ideal for moving sludge and slurries. Solids-laden fluids like sludge and slurry are hard to move -- unless you're using an air operated diaphragm pump.

Air is driven into the bottom of the air cylinder, raising the piston inside and lifting the diaphragm. As the diaphragm is raised, the check valve ball on the intake side is lifted and liquid flows into the pump. When the piston has risen to the top, the pump cavity is filled and the pump is ready for discharge.

Compressed air is then forced into the top of the diaphragm chamber, pushing the diaphragm down and evacuating the pump cavity. The check-valve ball on the discharge side is lifted and the pump is ready for the next cycle.

Because an air operated diaphragm has limited moving parts, there's almost nothing to maintain or wear out. Rebuild costs are reduced and are built for years of trouble-free operation.

FIGURE 7

4. AIR VESSEL:

What is Air vessel?Air vessels are a closed container, in which the half part is filled with

water & upper half part is filled with compressed air. These air

vessels installed very near to the suction valve & delivery valve to

avoid the separation.

FIGURE 8

Why an Air Vessel is fitted?An air vessel usually fitted in the discharge pipe work to dampen out the

pressure variations during discharge. As the discharge pressure rises the air

is compressed in the vessel, and as the pressure falls the air expands. The

peak pressure energy is thus stored in the air and returned to the system

when pressure falls. Air vessels are not fitted on the reciprocating boiler

feed pumps since they may introduce air into the de-aerated water.

Purposes of Air vessel:1) To obtain liquid at uniform discharge.2) Due to air vessel frictional head and acceleration head decreases and the

work overcoming friction resistance in suction and delivery pipe considerably decreases which results in good amount of work.

3) Reciprocating pump can run at high speed without flow separation.

Working:The top half contains compressed air and lower half contains fluid being

pumped. Air and water are separated by a flexible diaphragm which is

movable as per difference of pressure between two fluids. Air vessel is

connected very near to the pump at nearly pump level. Without air vessel

frictional head increases and reaches a maximum value at mid stroke and

decreases to zero. With air vessel frictional head is constant throughout the

stroke.

Flow into and out of Air vessel:1) Single acting pump: the flow into delivery side is only during a half

revolution. This amount has to flow during full revolution.

≫The average velocity in the pipe = 2 ln60 * Aa

2) Double acting pump: there are two discharges per revolution.

≫The average velocity in pipe = = 2 ln60 * Aa

3) Frictional head (h f):h f=¿4 fl v2

2gd ¿

5. THEORATICAL POWER RWQUIRED:

Pactual = PthEfficiency of pump = ρgQ (H s+H d)

η

Where, ρ = density of liquid, Kg/m³

Q = discharge, m³/s

H s = suction head, m

H d = delivery head, m

CONCLUSIONIn this seminar I studied deeply about Reciprocating Pump and know their

working, types and construction. It is satisfactorily said that Reciprocating Pump

have many advantages but disadvantage to. It can be efficient in favorable

conditions.