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Marine Engineering > Marine Pumps > Flashcards

Marine Pumps Flashcards

1
Q

It is a mechanical device used to transfer liquids from one point to another by imparting energy supplied by a prime mover to the liquid.

A

Marine Pumps

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2
Q

The prime mover can be an electric motor, an I.C. engine, or a steam engine or turbine. True or False?

A

True

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3
Q

TWO CLASSIFICATION OF PUMPS USED ON BOARD

A
  1. Positive Displacement Pump
  2. Dynamic Pressure or Roto-Dynamic Pump
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4
Q

They are self-priming pumps and are normally used as priming devices.

They consist of one or more chamber, depending upon the construction, and the chambers are filled and emptied.

Produces High Pressure into the Pumping System

A

Positive Displacement Pump

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5
Q

Examples of Positive Displacement Pump

A
  • Reciprocating Pump
  • Screw pump
  • Gear pump
  • Piston pump
  • Ram type pump
  • Vane pump
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6
Q

during pumping action, tangential force is imparted which accelerates the fluid normally by rotation of impeller.

it may require positive displacement pump for priming

low viscosity fluids are used

A

Dynamic Pressure or Roto-Dynamic Pump

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7
Q

Examples of Dynamic Pressure or Roto-Dynamic Pump

A
  • Centrifugal pumps
  • Axial flow pumps
  • Submersible pump
  • Centrifugal-axial (mixed) pump
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8
Q

Examples of Prime Mover

A

Electric Motor
I.C. Engine
Steam Engine
Turbine

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9
Q

Positive displacement pumps are ____ priming. Discuss what priming is this.

A

sself-priming- Automatically evacuate air from the suction linea and prime themselves without any external factors or priming assistance

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10
Q

How many chambers does Positive Displacement have?

A

one or more chamber

depending upon the construction, and the chambers are filled and emptied.

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11
Q

Discharge Rate of Positive Displacement Pump

A

Small to Medium

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12
Q

Dicharge rate of Dynamic Pressure / Roto-Dynamic Pump

A

Moderate to High

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13
Q

Pressure of Roto-Dynamic Pump

A

Low to Moderate

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14
Q

Use kinetic energy to move fluid using a rotating impeller, providing a continuous flow and are commonly used in marine applications for their flow rates and simple design.

A

Centrifugal Pumps

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15
Q

It moves fluid by trapping a fixed amount of it and forcing it into the discharging pipe, making them suitable for high-viscosity fluids and precise flow control in marine applications.

A

Positive Displacement Pumps

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16
Q

Use a piston or diaphragm to displace fluid, making them ideal for high-pressure applications, such as the water jet propulsion in marine vessels.

A

Reciprocating Pumps

17
Q

It transfers fluids using a rotating element such as gear or lobes, providing reliable and efficient solutions for marine fuel transfer and lubrication systems

A

Rotary Pump

18
Q

KEY CONSIDERATIONS IN MARINE PUMP SELECTION

A
  • Flow Rate
  • Pressure Head
  • Power Requirements
  • Fluid Compatibility
  • Space Constraints
  • Operating Conditions
19
Q

EFFICIENCY OPTIMIZATION TECHNIQUES FOR MARINE PUMPS

A
  • Pump System design
  • Pipe Sizing
  • Energy-Saving Technologies
  • Variable Frequency Drives
20
Q

MAINTENANCE, TROUBLESHOOTING OF MARINE PUMPS

A
  • Regular Maintenance
  • Inspection
  • Lubrication
  • Common Issues
  • Troubleshooting
21
Q

RELIABILITY ENHANCEMENT STRATEGIES FOR MARINE PUMPS

A
  • Redundancy
  • Preventive Maintenance
  • Condition Monitoring
  • Spare Parts Management
22
Q

ENVIRONMENTAL CONSIDERATIONS IN MARINE PUMP OPERATION

A
  • Pollution Prevention
  • Ballast Water Management
  • Fuel Efficiency
23
Q

REGULATORY COMPLIANCE FOR MARINE PUMP SYSTEMS

A
  • International Maritime Organization (IMO)
  • Classification Society Standards
  • Certification
24
Q

This is a rotary displacement or a rotary positive displacement pump

This pump is used as lube-oil pump, boiler fuel pump, fuel oil transfer pump, and main engine lube-oil pump.

A

Gear Pumps/Gear Wheel Pump

25
Q
  1. There are two gears, one is driven by an electric motor through a chain or wheel drive. The other gear is known as the idler gear.
  2. Initially, when there is no liquid in the pump casing, there is air inside it.
  3. As the gears start to move, the air gets trapped between each pair of two consecutive teeth and dragged along the casing to the discharge side until there is no air left.
  4. Liquid from the tank will thus rises into the suction side and is discharged in a similar manner.
  5. For this reason, the pump is a self-priming pump. These pumps give slow discharge rate but a high discharge pressure.
  6. The flow rate is controlled by controlling the speed of the prime mover and by the help of a by-pass valve attached to the suction and discharge lines.
A

Gear Pumps/Gear Wheel Pump

26
Q

This type of pump contains two shafts, each shaft has two screws, one right-handed and the other left-handed.

A

Screw Pumps

27
Q
  1. These screws are driven in phase by timing gear, unlike the gear pump in which one gear drives the other. This ensures that correct clearance is maintained between the screws. This avoids overheating and a possible seizure.
  2. When the screws rotate, their close relation to each other causes small pockets on the helices, these pockets move axially and have the same effect as the piston moving constantly in one direction.
  3. This type of pump has a suction side on the outer ends from the liquid is drawn into the screws and pumped inwards to discharge into the pump outlet.
  4. Even if the liquid level in the tank is below the pump level, the pump first draws in air of gases and creates a vacuum in the line, the liquid, therefore, rises up and reaches the pump.
  5. A relief valve is fitted to avoid build-up of excessive pressure.
A

Screw Pumps

28
Q

Advantages of Screw Pumps

A

 Is self-priming, thus is very useful for high vapor pressure liquids
 Since these pump can discharge both liquids and gases, they are very useful for tank draining and where the liquid flow is not constant, which may occur in lube oil systems of main engines, with the vessel rolling and pitching.
 They are suitable for operation at high rpm, and thus can be driven by electric motor
 They are good for high viscosity fluids, pumps are quiet, smooth running and reliable.

29
Q

This type of pumps have a bucket type piston inside a cylinder liner, the bucket is lined with piston rings.

A

Double Acting Reciprocating pump

30
Q
  1. The bucket is connected to independent set of spring style type discharge and suction valves.
  2. The liner is connected to independent sets of spring type discharge and suction valves.
  3. The downward movement of the bucket creates a vacuum on the top of the bucket. Due to this, the suction valve of the top set opens and draws liquid into the air.
  4. The upward movement of the bucket creates a suction below the bucket, the suction valve in the bottom set now and draws liquid into the liner.
  5. The upward movement of the bucket also causes the liquid on the top of the bucket to be forced into the top set, thus causing the discharge valve to lift. As the discharge valve lifts, the liquid flows into the discharge line.
  6. The next downward movement cause the similar effects as explained in point 3.
  7. As this pump causes liquid to be discharged from both top and bottom, it is known as double acting reciprocating pump.
  8. An air vessel is provided in the discharge line to reduce the pressure fluctuations caused by up and down movement of the bucket.
  9. A relief valve is also provided to avoid excessive pressure build up.
A

Double Acting Reciprocating pump

31
Q

Advantage of Double Acting Reciprocating Pump

A
  1. As they handle large volumes of air/gases, they can be used as stripping (draining) pumps for oil, chemical or gas tanks.
  2. As they are self-priming and can handle high suction lifts, they can be used as priming pumps, engine room bilge pumps and cargo hold bilge pumps.
32
Q

Disadvantage of Double Acting Reciprocating Pump

A
  1. Construction is complicated due to presence of suction valve, discharge valve, air vessel and relief valve. All positive displacement pumps need a relief valve to prevent excess built up of pressure if delivery lines are closed.
33
Q
  • machine that uses rotation to impart velocity to a liquid and then converts that velocity into flow
  • hydraulic machine that converts mechanical energy into hydraulic energy by means of a centrifugal force acting on the fluid.
A

Centrifugal Pump

34
Q
  1. This type of pump contains rotating impeller with a stationary casing.
  2. The impeller consists of curve vanes.
  3. There is an opening, eye of the center, from where the liquid is drawn into the pump.
  4. The impeller is connected to an electric motor by means of a shaft.
  5. The impeller rotates at a very high speed.
  6. Fluid is thrown upward by the blades, due to centrifugal force.
  7. The high-velocity fluid is collected in a specially shape volute casing, where some of the kinetics energy is converted into pressure energy.
  8. The fluid under pressure now leaves the impeller producing a drop in pressure behind in the eye of the impeller.
  9. This causes the liquid from the suction line to flow into the pump, this thick fluid is also subsequently thrown out, the process continues,
  10. This is possible only when there is fluid in the pump initially.
  11. If there is no liquid initially, there will be air. As the air is very light density, for a centrifugal pump to throw out air, it will have to rotate at a very very high speed. (turbocharger blower)
  12. For the above reason, a centrifugal pump is not a self-priming pump. It has to initially primed with fluid.
A

Centrifugal Pump

35
Q

Priming of Centrifugal Pump

A
  1. Use an air pump to initially drive out air form the suction branch and thus make the liquid rise into the eye of the impeller. Example emergency fire pump, bilge and ballast pump.
  2. Priming can be also done by opening the sea chest valve, so that the water which is at a higher level, flows inside the eye. Once liquid flows into the eye of the rotating impeller, suction can be changed over from the seaside to engine room bilges etc. and pumping can now commence.

Marine Engineering (3 decks)

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