Reciprocating pump Questions with Answers

What is Reciprocating pump ?

The reciprocating pump is a positive displacement pump in which a certain quantity of liquid is collected in an enclosed space and discharged to the point of application using pressure. Reciprocating pumps are more preferable for low volumes of flow but at high pressures.

In Other words, It is a positive displacement pump that uses a plunger or piston to adjust the volume of a cavity and create a differential in pressure.

Working of reciprocating pump ?

Stepwise working of Reciprocating Pump :

  1. The crank will begin to rotate when the power source is connected to the crank, and the connecting rod will also be displaced along with the crank.

2. The attached piston to the connecting rod travels in a linear direction. When the crank moves outward, the piston moves to the right and creates a vacuum in the cylinder.

3. This vacuum causes the suction valve to open and the suction pipe forcibly sucks liquid from the source into the cylinder.

4. The piston will move to its left when the crank moves inwards or towards the cylinder and compresses the liquid in the cylinder.

5. The force now allows the outlet valve to open and the liquid will discharge through the outlet pipe.

6. All the liquid present in the cylinder is delivered via the delivery valve when the piston reaches its extreme left position.

7. Then the crank rotates outward again and the piston shifts right to produce suction, repeating the whole operation.

8. The above mechanism can usually be observed in a single reciprocating acting pump where there is only one delivery stroke per crank revolution. But when it comes to reciprocating double acting pumps, there will be two delivery strokes per crank revolution.

Which pump is more efficient, centrifugal pump or reciprocating pump?

Why is priming necessary for centrifugal pump and not in reciprocating pump?

One important thing is to note that the centrifugal pump is not self-priming. So, in order to make it functional, it needs to be primed.

PRIMING  Priming is the process in which the suction pipe , casing, and delivery pipe upto the delivery valve is filled completely with liquid to be raised from outside source before starting the pump. Priming is done to remove the air from the pump.

If the air is not removed from the pump then only a small negative pressure is created at the suction pipe and it cannot suck the water from the water sump.

While in reciprocating pump the suction pressure is created by the movement of the plunger or the piston so there is no need of priming.

How do reciprocating pumps work?

What happens if the delivery valve of a running reciprocating pump is closed?

For industrial reciprocating pumps, PSV is mounted (highly recommended) with proper set pressure at the discharge of the pump as required by the process. So even though the discharge valve is closed, the pressure will increase to the PSV set point and then the PSV will pop up to relieve the pressure. There will be no harm to the pump and its discharge mechanism in this situation (except some process delay).

If PSV is not mounted, after high over-pressure the line will burst.

Why is the reciprocating pump is called positive displacement pump?

In comparison to centrifugal and non-positive displacement pumps, positive displacement pumps, despite variations in discharge pressure, provide a constant flow at a given velocity. Positive displacement pumps have an expanding cavity during suction and a cavity during discharge that decreases or collapses.

Application of reciprocating pump ?

  • Oil drilling operations
  • Pneumatic pressure systems
  • Light oil pumping
  • Feeding small boilers condensate return

Reciprocating pump diagram

What is working principle of reciprocating pump ?

The reciprocating pump is a Positive Displacement type pump that acts in forward and backward directions on the principle of piston movement, while the centrifugal pump uses the kinetic energy of the impeller to supply the liquid from one position to another.

Types of reciprocating pumps ?

Reciprocating pump vs centrifugal pump

Efficiency of reciprocating pump

Characteristics of reciprocating pump ?

Why reciprocating pump is positive displacement ?

Why air vessel is used in reciprocating pump?

Positive displacement pump are fitted with air vessel  usually in the discharge pipeline to dampen out the pressure variation 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.

Function of the Air Vessel

  • To get the continuous flow of water at a uniform rate.
  • To reduce the amount of work in overcoming the frictional resistance.

Operation of centrifugal pump

What is slip in reciprocating pump ?

Reciprocating pump maintenance ?

Reciprocating pump performance curve

Overhauling proces of reciprocating pump ?

What is the difference between centrifugal pump and reciprocating pump?

Why slip occurs in reciprocating pump?

What is the Reciprocating pump start up procedure?

What is priming why it is not done on reciprocating pumps?

How can the slip of a reciprocating pump be negative?

What are the applications of a single acting reciprocating pump and a double acting reciprocating pump?

Which will provide a greater head centrifugal or reciprocating pump?

What leads to the failure of reciprocating pumps?

Does cavitation occurs in reciprocating pump?

What is reciprocating pump and its principle?

Is NPSH required for reciprocating pump?

What is the physical difference between reciprocating compressor and reciprocating pump?

Why a reciprocating pump produce high head but low discharge?

Why a centrifugal pump is more efficient than reciprocating pump?

Why the reciprocating pump are begin used for dosing chemicals?

Can we use a reciprocating pump as an engine for cars?

What is the purpose of reciprocating pumps?

What is priming? Why is priming not required in reciprocating pump but used in centrifugal pump?

What is positive slip in reciprocating pumps?

Why are reciprocating pumps called constant volume pumps?

What is the equation for calculating reciprocating pump efficiency?

Is a negative slip in reciprocating pumps a good thing?

Why is the speed of a reciprocating pump lower than a centrifugal pump?

What is the normal efficiency of a reciprocating pump?

In reciprocating pump there is work of pressure or not?

What are the applications of reciprocating pumps?

Why is a reciprocating pump not coupled directly to a motor?

What is the main reason of cavitations in reciprocating pump?

Is compressor pump a type of reciprocating pump?

How are reciprocating pumps classified?

Why does not centrifugal pump give a constant flow but reciprocating pump does?

What is the working of a reciprocating pump?

How do I increase the head of a reciprocating pump?

Which pump have the advantage of both centrifugal pump and reciprocating pump?

What is the characteristics of reciprocating pump at constant speed?

What is the separation in a reciprocating pump?

Why is a centrifugal pump’s efficiency less than a reciprocating pump?

What are the characteristics curve of a reciprocating pump?

What is air binding in reciprocating pump?

What is meant by cavitation in a reciprocating pump?

Does flow in reciprocating pump change with head?

Is a reciprocating pump used for high head or high discharge?

Which reciprocating pump is good, one with a positive slip or the one with a negative slip?

What is acceleration head in a reciprocating pump?

What is the procedure for an overhaul reciprocating pump?

What are the materials for a reciprocating pump?

How do you increase efficiency in a reciprocating pump?

Why can a centrifugal pump deliver water to lower head better than a reciprocating pump?

Where are the reciprocating pumps used?

Can a reciprocating pump be used as reciprocating compressor for compressing gases?

What is the difference between submersible and reciprocating pump?

Why can’t we use reciprocating pumps in a series?

Can gases be pumped by a reciprocating pump?

Whether Human Heart lies in the category of centrifugal pump or a reciprocating pump?

What is a write note on a reciprocating pump?

Which pump has a high efficiency, a centrifugal or a reciprocating pump, and why?

What will happen if the discharge valve of a centrifugal pump and reciprocating pump is closed?

What is the formula for theoretical flow (for a reciprocating pump)?

When does the slip in a reciprocating pump become negative?

Is there any difference between cavitation and seperation in centrifugal or reciprocating pump? Does they refer to the same incident?

Can reciprocating pumps be used in series or in parallel?

What is the function of a relief valve in a reciprocating pump assembly?

Why does a reciprocating pump have a higher efficiency than a centrifugal pump?

What are the major failures of reciprocating pumps?

What is relation between the pressure head and pump efficiency of reciprocating pump?

What will happen if both suction and discharge valves are closed in a reciprocating pump and it is started?

Reciprocating pumps are not directly coupled to the prime mover. Why?

What will happen if I shut down the fluid discharge if an air-operated reciprocating pump?

How do I operate a reciprocating pump?

Why is an air vessel in a reciprocating pump filled with water?

Why are reciprocating pumps generally used for metering and dosing purposes? Why not centrifugal pumps?

Why is there an escape route for fluid in the inlet valves of a reciprocating pump?

Which type of oil is used for a manually operating reciprocating pump?

Can we use a centrifugal pump instead of a reciprocating pump? If not, then why?

Can reciprocating pumps be used in series or in parallel?

Why don’t we use centrifugal pumps instead of reciprocating pumps?

What are the applications of reciprocating pump in industry and engineering field?

If the suction pressure is decreased in a reciprocating pump, what will be the effects on discharge pressure? Will it increase or decrease?

How is the Bernoulli principle used in a reciprocating pump?how can we calculate work by this principle?

Which type of pump is better for manually operating hand pump or reciprocating pump or any other pump?

What will happen if we operate reciprocating pumps in a series?

Is there any specific curve for reciprocating pumps to calculate the flow rate (m3/h), head (in m), etc.?

Why is the reciprocating pump also known as a positive displacement pump and what is positive displacement in terms of pump mechanism?

Can you draw different chatestic curve of a reciprocating pump?

What are air vessels in a reciprocating pump for?

What is the relation between velocity and pressure in reciprocating pump?

What will happen if you run a reciprocating piston pump without opening a discharge valve?