Reciprocating pumps: Components, advantages and disadvantages

A positive displacement (PD) pump is a machine that physically transfers a predetermined quantity of fluid from one location to another. Piston, plunger, or diaphragm pumps that move back and forth repeatedly are a subset of positive displacement (PD) pumps. One type of PD pump is the reciprocating pump. Fluid is pushed through the pump by a technique known as reciprocation, which involves a cyclical motion. This is what gives it its name.

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See also: Centrifugal pumps: What are they, and how do they work?

Reciprocating pumps: Components

This reciprocating pump consists of the following components:

Cylinder

The connecting rod between the piston and the crank allows the piston to move back and forth inside the cylinder and generates torque.

Piston and piston rod

The piston within the cylinder travels back to initiate suction, then forward to release liquid.

Suction pipe

Using a suction pipe, a reciprocating pump draws water from a storage tank. A suction valve is used to transfer the water to the storage cylinder.

Suction valve

The suction valve, or non-return valve, is located at the entrance of the suction pipe. Since the suction pipe leads only into the cylinder, the water can only flow forward. Therefore, this valve only allows only one direction of flow.

Water sump

The water sump supplies the cylinder or pump with water, as the name indicates. Pistons draw water from this reservoir and push it toward the supply lines.

Strainer

The strainer, situated at the suction pipe’s end, performs a crucial function in removing debris from the liquid being drawn in. It may also be used as a filter to keep debris like dirt and dust out of the discharged water.

Air vessels

The term “air vessel” is used to describe a closed container made of cast iron with two openings at opposite ends. To allow liquid to flow into the vessel, one end of the cylinder remains open at its base. Air vessels are installed in both the suction and delivery pipes of the pump to provide a consistent flow.

Crank and connecting rod

For the crank to turn, it must be coupled to a driving force. It has the form of a flat, round disc.

Delivery pipe

A delivery pipe’s job is to transport water from one site to another. The water in the cylinder is transported by this pipe. In addition, it links the pump’s cylinder to the output.

Delivery valve

Another name for this valve is “non-return valve,” and it functions similarly to the suction valve. It allows water to be released from the storage tank into the delivery line.

Reciprocating pumps: Working principle

A reciprocating pump’s major components are a piston, plunger, or diaphragm. This operates in a chamber whose volume ultimately determines the pump’s output. A connecting rod extends from the crank of a motor to the piston, plunger, or diaphragm. The fluid may be sucked into the chamber by the suction pipe, and then released via the delivery pipe. The passage of fluid into and out of the chamber is regulated by inlet and exit valves.

Reciprocating pumps: Various uses

Boiler feeding
Wet sandblasting
High-pressure pumps for the RO system (Reverse osmosis)
Fire Fighting system
Pneumatic pressure applications
Vessel, pipe, tank, tube, condensate pipe, heat exchanger, etc.
Vehicle cleaning
Sewer line cleaning
Wastewater treatment system
Oil drilling, refineries, production, disposal, injections
Hydro testing of tanks, vessels, etc.

The centrifugal pump vs the reciprocating pump

In comparison to centrifugal pumps, a reciprocating pump has distinct advantages in a variety of operational, design, and practical contexts. The liquid is propelled in a centrifugal pump by an impeller, whereas in a reciprocating pump, a piston does the heavy lifting. Unlike their reciprocating-piston-based counterparts, centrifugal pumps constantly expel their liquid. They are more portable and affordable than reciprocating pumps and are used for fluids with a high viscosity.

Reciprocating pumps: Advantages

Power requirements for a reciprocating pump might be as little as one horsepower or as high as three thousand.
Low-flow, high-head applications are ideal for reciprocating pumps. In water jet cutting, for example, pressures of over 10,000 PSI are achieved with just a few gallons of water passing through the pump every minute.
Some of the harshest and most corrosive environments need the usage of reciprocating pumps. Materials including stainless steel, aluminium bronze, tungsten carbide, ceramic, and more may be used to construct fluid ends and fluid end components.
When compared to other types of pumps, the efficiency of a reciprocating pump is much greater. At a given pressure setting, reciprocating pumps typically operate at a 90% efficiency rate.

Reciprocating pumps: Disadvantages

High maintenance and a relatively limited lifespan are the major drawbacks of a reciprocating pump.
Compared to a centrifugal pump, a reciprocating pump needs more frequent maintenance and rebuilding.
When compared to more durable and costly pump types, the cost to repair a reciprocating pump is often low.
Pressure pulsations at the pump’s input and outflow are a signature of reciprocating pumps.
To lessen the pulsations caused by the pump, increasing the number of chambers is helpful.
Pulsation dampeners must be fitted on a pump to prevent damage to the pump and its surrounding infrastructure.

Reciprocating pumps: Different varieties

Single-acting reciprocating pump: There is one intake and one outlet on this. The delivery valve opens and the liquid is released when the piston is pushed forward, while suction occurs when it is moved backwards.
Double-acting reciprocating pump: There are two suction and delivery valves, making this pump more versatile than a single-functioning pump. As a result, it needs two pipes-one to bring in air and one to let it out. These pumps are often used in a wide variety of settings, including saltwater disposal, well service, descaling, hydraulic fracturing, and oil and gas pipelines.
Double acting -Air and Steam pumps: These pumps are double acting, meaning they employ steam, air, or gas to move liquid. They have a relatively large operating pressure and flow range, allowing them to function in a wide variety of conditions.
Simplex, Duplex, Triplex, Quintuplex Pumps: A common cylinder configuration for reciprocating pumps is a simplex, duplex, or triplex arrangement. These pumps have a wide variety of uses, including oil-line pumping, mine dewatering, and the transport of chemical and petroleum products. It is often used in cement slurries, fluids including sand, crude oil, acids, mud, and other fluids used in oil well maintenance.
Metering Pumps: When controlling the quantity of liquid delivered over a certain time, a metering pump is often used. Most metering pumps are piston-driven Piston pumps. When operating against a discharge pressure, piston pumps may maintain a constant flow rate.

FAQs

What is a reciprocating pump used for?

Reciprocating pumps are used when a precise amount of fluid needs to be moved, or when a higher pressure than other types is needed. A piston that moves in a cylinder moves the fluid around.

What is a reciprocating pump and how does it work?

The positive displacement principle is how the reciprocating pump works. A reciprocating piston pump has a piston that moves back and forth in a tube. The piston is connected to the crankshaft by a connecting rod. When the crankshaft turns, the connecting rod moves, which moves this piston.

How are centrifugal and reciprocating pumps different?

The flow rate from the reciprocating pump stays almost the same over a wider range of pressure. The pressure from the centrifugal pump stays the same over a range of flow, but it drops dramatically as the flow rate goes up. As the pressure goes up, the viscosity of the fluid has little effect on the flow rate of a pump that moves back and forth.