Tag Archives: Centrifugal Pumps

Paradigm Shift Towards Solar Powered Centrifugal Pumps

Excerpt from the Sept. 2019 article from Modern Pumping Today by Dave Namrata

Rapidly changing agricultural technology combined with constant improvement in farm machinery is leading to wide adoption of energy-efficient centrifugal pumps, creating pressure and flow in the irrigation system. Solar-powered water pumping system in agriculture is gaining popularity as an alternative to grid electricity. The modern agricultural system has led to the growing demand for irrigation solutions that reduces energy cost, improves productivity and safeguards water resource. Moreover, a reduction in the price of solar panels and components in solar power systems is driving the adoption of solar-powered centrifugal pumps and emerging as an economically viable option for irrigation.

The growing concern towards wastewater treatment in the past few years has resulted in wide application of centrifugal pumps. Rising competitiveness in the market is resulting in the development of centrifugal pump technology leading to better performance and reduction in the overall cost. From a design perspective, manufacturers of centrifugal pumps are focusing on improving the quality of shaft steel in the pumps to withstand vibration, fatigue, and stress. According to some industry experts, water shortage is likely to impact more than half of the world population by 2025. This is accelerating the wastewater treatment process across the countries.

Increasing energy costs and growing environmental awareness are motivating pump manufacturers to focus on developing energy-efficient centrifugal pumps for the end-use industries. Moreover, centrifugal pumps operating at a high speed pumping a large amount of liquid consume more power. This is leading to the integration of economically feasible and reliable solar power in the centrifugal pumping system.

Long product life and low maintenance cost of solar-powered centrifugal pumps are emerging as the perfect alternative to other pumping systems. Industries consider various factors while selecting a pumping system, such as pump lifecycle cost, including initial cost, maintenance cost and energy cost. On average, centrifugal pumps can consume around 60 percent of motor energy in the facility resulting in higher energy and maintenance costs.

Centrifugal Pumps
Centrifugal pumps generated by solar power

 

Increasing Focus on Energy Efficiency

In recent years, with an increasing cost of energy worldwide, energy efficiency is gaining attention from governments and pump manufacturers across countries. Despite various challenges, pump manufacturers are adding sustainable design features, enhancing productivity, quality, and services.

Solar-powered centrifugal pumps have gained popularity and are available on a large scale in the developed countries. However, the high initial cost of solar-powered centrifugal pumps as compared to the cost of fuel-powered pumps is the main obstacle for solar pumps in developing countries. This is driving the pump manufacturers in the developing regions to design next generation, cost-effective solar powered centrifugal pumps, eliminating the need for grid connection or fossil fuel.

Use of solar photovoltaic technology for centrifugal pumping system has gained immense popularity. Continuous reduction in solar cells cost is likely to drive the application for centrifugal pumps powered by the solar photovoltaic system in agriculture and other industries.

solar panels for centrifugal pumps
Solar panels for centrifugal pumps

With an aim to save the energy cost, replacement and refurbishing of the pumping system in water and wastewater treatment industry is on the rise. There has been a rise in the adoption of centrifugal pumps powered by solar energy in this industry.

Driven by rapid industrialization and urbanization, municipal water and wastewater industry in emerging countries is creating growth opportunities for centrifugal pumps manufacturers. However, manufacturers are facing a flood of new competition due to the increasing demand for energy-efficient pumps and stringent regulations. According to the American Hydraulics Institute, around 30 percent of the total electrical energy consumed by pumping systems can be saved by developing a highly efficient system and using appropriate pumps.

First-generation PV pumping systems using centrifugal pumps have shown significant advancements in recent years. The current solar-powered pumping technology uses an electronic system by further increasing the output power, performance and efficiency. PV modules account for nearly 60 to 80 percent of the total cost of PV system. A significant decline in the cost of PV modules across various regions has also reduced the overall cost of the pumping system. Moreover, an increase in the cost of crude oil, diesel, and gasoline has made solar powered pumps financially attractive.

There exists immense growth opportunity for centrifugal pumps in wastewater, pharmaceuticals, food and beverage, and chemical industries, as the sectors are set to grow at a stable pace in the near future. However, centrifugal pump demand will continue to be hit by the nuclear power generation, mining, and oil and gas sectors, which are likely to experience slow growth.

>>Read more.


A Complete Line of Pumps for Industry

Vertiflo Pump Company’s Vertical Sump Centrifugal Pumps, Horizontal End Suction Centrifugal Pumps and self-priming pumps are delivered fast, usually in half the typical lead time. Vertiflo’s vertical sump pump line offers up to 3000 GPM, 250′ Heads and 26′ depth. The horizontal end suction pump line offers up to 3000 GPM and 300’ Heads.

Vertiflo pumps are designed for nonresidential applications and currently over 20,000 are operating successfully worldwide. Vertiflo is recognized as a quality manufacturer of dependable pumps, and continues to grow and encompass new applications in the pump industry.

Minimum Continuous Stable Flow

Centrifugal Pump Flow Operating Regions and Impact on Reliability

Ideally, a centrifugal pump should be operated at or near its best efficiency point (BEP) flow rate in order to minimize the life cycle costs. However, all centrifugal pumps have sweet spots beyond the BEP that will yield acceptable efficiency and reliability.

Excerpt from the Sept. 2016 article from WaterWorld

There are limitations, though, on the minimum and maximum flow rates, beyond which the pumps should not be operated continuously (or for an extended period of time), in order to avoid premature failures.

A first step in avoiding these negative, low-efficiency and low-reliability conditions is to determine the pump BEP, preferred operating region (POR), and allowable operating region (AOR) flow rates. It is especially important to determine these flow regions because not all pump applications are static in nature or closely match the expected system demand. Because of this, pumps are often required to operate over a broad range of flow rates, which can adversely affect the pump efficiency and reliability.

Centrifuge Flow Reliability Factor

A pump will always operate at the flow rate where the pump head-capacity curve intersects the system head-capacity curve. This means that it is also critical to accurately determine the true system H-Q curve, in order to establish the true operating flow rates.

Once these flow regions and the true system conditions are known, actions can be taken to maximize pump operation in the POR and avoid or minimize operation outside the AOR, thus optimizing pump life cycle costs.

BEP Flow Region

Pump performance and service life are optimized around a rate of flow designated as the BEP. At the BEP, the hydraulic efficiency is maximum, and the liquid enters the impeller vanes, casing tongue (discharge nozzle), and diffuser vanes in a shockless manner. At the BEP, flow through the impeller and diffuser vanes (if so equipped) is uniform, free of separation, and well-controlled.

Minimum Continuous Stable Flow

Lower and higher flow rates cause mismatch between the flow and the impeller and casing vanes. This mismatch causes turbulence within the impeller and casing flow passages, which both block the flow passages and increases the local velocities. This increase in velocity increases vaporization (cavitation) within the liquid. The greater this resulting turbulence and cavitation, the lower the pump efficiency and reliability, and the more severe are the levels of vibration, noise and erosion.

>>Read more.


A Complete Line of Pumps for Industry

Vertiflo Pump Company’s Vertical Sump Centrifugal Pumps, Horizontal End Suction Centrifugal Pumps and self-priming pumps are delivered fast, usually in half the typical lead time. Vertiflo’s vertical sump pump line offers up to 3000 GPM, 250′ Heads and 26′ depth. The horizontal end suction pump line offers up to 3000 GPM and 300’ Heads.

Vertiflo pumps are designed for nonresidential applications and currently over 20,000 are operating successfully worldwide. Vertiflo is recognized as a quality manufacturer of dependable pumps, and continues to grow and encompass new applications in the pump industry.

What is a Centrifugal Pump?

centrifugal pump is a machine that uses rotation to impart velocity to a liquid and then converts that velocity into flow.

Excerpt from introtopumps.com

Let’s break that definition down into its components so that we can consider each one in turn:

  1. A centrifugal pump is a machine.
  2. A centrifugal pump uses rotation to impart velocity to a liquid.
  3. A centrifugal pump converts velocity into flow.

Every centrifugal pump includes an assembly of mechanical components that make operation of the pump possible. This mechanical assembly includes the pump shaft mounted on bearings, the sealing mechanism that keeps the pump from leaking excessively, structural components designed to handle the stresses and loads imposed on the pump during operation, and wear surfaces that allow the pump to be repaired and returned to its original specifications.

Every centrifugal pump includes an impeller. The impeller is the hydraulic component that rotates to impart velocity to the pumped liquid.

Every centrifugal pump includes a casing. The casing is the hydraulic component that captures the velocity imparted by the impeller and directs the pumped liquid to the pump discharge point.

At the most fundamental level, a centrifugal pump consists of just these three components:

  1. An impeller that rotates and imparts velocity to a liquid.
  2. A casing that captures the velocity generated by the impeller and transforms that velocity into a stable flow.
  3. An assembly of mechanical components that makes it possible for the impeller to be rotated within the pump casing.

>>Read more.


A Complete Line of Pumps for Industry

Vertiflo Pump Company’s Vertical Sump Centrifugal Pumps, Horizontal End Suction Centrifugal Pumps and self-priming pumps are delivered fast, usually in half the typical lead time. Vertiflo’s vertical sump pump line offers up to 3000 GPM, 250′ Heads and 26′ depth. The horizontal end suction pump line offers up to 3000 GPM and 300’ Heads.

Vertiflo pumps are designed for nonresidential applications and currently over 20,000 are operating successfully worldwide. Vertiflo is recognized as a quality manufacturer of dependable pumps, and continues to grow and encompass new applications in the pump industry.

Net Positive Suction Head Cavitation in Centrifugal Pumps

How to Understand Net Positive Suction Head

There are two ways of expressing NPSH relative to a centrifugal pumping system.

Excerpt from the August 2020 Pumps & Systems article by Gary Dyson

To make the term net positive suction head (NPSH) more accessible to pump engineers who may not understand how to design an impeller for NPSH or the exact details of the physics, I have tried to simplify it:

  • NPSH is a measure of the absolute pressure energy present in a liquid. Pump engineers use this energy to help “feed” the fluid into the eye of the first-stage impeller. Pumps generally do not suck.
  • NPSH is the sum of the total static plus kinetic pressure minus the liquid vapor pressure at the pump suction nozzle or impeller entry, which is expressed in terms of head.
Net Positive Suction Head Cavitation in Centrifugal Pumps
Net Positive Suction Head Cavitation in Centrifugal Pumps

There are two ways of expressing NPSH relative to a centrifugal pumping system:

  1. NPSHa—The net positive suction head available is the measurement of the amount of fluid pressure energy available from the system at the pump impeller inlet.
  2. NPSHr—The net positive suction head required is the measurement of the amount of fluid pressure energy required by the pump.

The NPSH available to the pump should be more than what the pump requires. If there is not enough NPSHa, the pump will cavitate. As a result, the performance and reliability can be compromised.

Impeller Blade Cavitation from Bubbles
Impeller Blade Cavitation Damage from Collapsing Bubbles

NPSHr Curves

NPSHr curves, as provided by the pump manufacturer, are generated using the data collected during a pump performance test. Determining NPSHr requires testing the pump over a series of carefully controlled, constant flow points and varying suction conditions in a test facility. The test lab operator sets the flow and then begins to introduce a vacuum on the suction side of the pump. This reduces the suction pressure in controlled increments. While reducing the suction pressure, the discharge pressure is closely monitored.

>>Read more.

 


A Complete Line of Pumps for Industry

Vertiflo Pump Company’s Vertical Sump Centrifugal Pumps, Horizontal End Suction Centrifugal Pumps and self-priming pumps are delivered fast, usually in half the typical lead time. Vertiflo’s vertical sump pump line offers up to 3000 GPM, 250′ Heads and 26′ depth. The horizontal end suction pump line offers up to 3000 GPM and 300’ Heads.

Vertiflo pumps are designed for nonresidential applications and currently over 20,000 are operating successfully worldwide. Vertiflo is recognized as a quality manufacturer of dependable pumps, and continues to grow and encompass new applications in the pump industry.

Horizontal Centrifugal Pump Selection for Chemical Applications

Selecting the Right Pump for Chemical Applications

Review pump types and pick proper construction materials.

Excerpt from the February 2020 Pumps & Systems article by Pete Scantlebury

There are many considerations when selecting the right pump for chemical applications. When working with materials such as corrosive or flammable chemicals, extra care should be taken to ensure that the product selected is suitable.

Define the Fluid Characteristics

The safety data sheet (SDS) and chemical manufacturer or chemical distributor can provide required information such as fluid name, concentration, fluid temperature, specific gravity and viscosity at pumping temperature. If solids are present, determine at what concentration, particle size and hardness, and if the material is corrosive, flammable or combustible.

Describe the Application

The more detailed the description, the better. Make sure to verify:

  • What type of container is the chemical stored in? Is it a drum or tote, bulk storage tank, rail car or tanker truck?
  • Where will the fluid be moved? From a drum to a bucket, from a rail car to bulk storage, or simply recirculating in the same container, for example.
  • Is the liquid below the pump? In this case, a pump that is either self-priming or one that can be submerged in the liquid is needed.
  • What is the flow rate required? Flow rate is required to calculate friction loss in the piping system.
  • What is the total head or pressure required? Total head is based on the piping system and is used (along with flow rate) to help choose a pump.
  • What is the net positive suction head available (NPSHa)? It is the suction head made available to the pump and provided by the piping system. To avoid cavitation (causes erosion damage to pump components) the NPSHa must exceed the NPSH required (NPSHr).
  • How long will the pump be operating per day or week? This is important in evaluating energy costs. For example, if a pump is going to be operating many hours per day, a pump driven with an electric motor could have considerably lower operating costs compared to an air-driven pump.
  • Is it indoors or outdoors? What are the maximum and minimum ambient temperatures? This is important for the correct selection of the construction materials for the pump and motor.
  • What is the altitude? Higher altitudes reduce available lift if it is a self-priming application, reduces NPSHa and reduces cooling by an electric motors fan.

Pump Selection

There are many variables to the selection of the best pump type with the correct materials of construction.

  • Gather information on the fluid to be pumped.
  • Gather information on the hydraulic and application requirements.
  • Consult the experts. Consult with the chemical manufacturer, chemical distributor, pump manufacturers, local pump distributors, and even industrial supply catalogs that are experienced in the selection of chemical pumps.
Horizontal Centrifugal Pump Selection for Chemical Applications
Horizontal Centrifugal Pump Selection for Chemical Applications

Review Possible Pump Types

Here are some of the most common pump types for transferring chemicals.

Drum/barrel pumps: Ideal for transferring a wide variety of chemicals from pails, drums, totes [(such as intermediate bulk containers (IBCs)] and other containers used by chemical manufacturers to transport products to the user. These can be powered by electric, lithium ion battery or air motors.

Centrifugal pumpsProvide smooth flow and have a wide range of flows and head capabilities. These pumps are available in a wide range of materials and either mechanically sealed or sealless magnetically coupled. They are typically operated with electric motors.

Air-operated double diaphragm pumps: Versatile, simple to operate, and can pump solids and viscous fluids. They typically operate with compressed air.

Positive displacement pumps: Includes gear, rotary vane or piston pumps. These pumps are good with high viscosity fluids and can generate high pressures.

>>Read more.

 


A Complete Line of Pumps for Industry

Vertiflo Pump Company’s Vertical Sump Centrifugal Pumps, Horizontal End Suction Centrifugal Pumps and self-priming pumps are delivered fast, usually in half the typical lead time. Vertiflo’s vertical sump pump line offers up to 3000 GPM, 250′ Heads and 26′ depth. The horizontal end suction pump line offers up to 3000 GPM and 300’ Heads.

Vertiflo pumps are designed for nonresidential applications and currently over 20,000 are operating successfully worldwide. Vertiflo is recognized as a quality manufacturer of dependable pumps, and continues to grow and encompass new applications in the pump industry.

A Step-by-Step Approach to Pump Selection

Consider pipe sizing and motor power requirements before picking your pump.

Excerpt from the September 2018 Pumps & Systems article by Lev Nelik

Unless a brand new plant is being designed, users decide to replace a pump because of its age and wear or persistent reliability issues.

Plant engineers typically spend their time with the process to make sure machinery is working, water is flowing, power is produced, lights are up and no environmental problems are developing. They are not, as a rule, experts on any particular type of machinery.

They are basically generalists, having learned to rely on qualified suppliers, who are experts within their particular niche (pumps, centrifuges, boilers, generators, etc.). When a pump fails, it is usually replaced with a new one, without much analysis or discussion. If it continues to fail frequently, a new supplier is approached for a better, more reliable pump.

Occasionally, a relatively minor modification to the process, like an addition of a cooling (or heating) piping loop, for example, is needed. It may not be a particularly complex system, and hiring major design contractors may not be economical for such a small project. Yet, it might still be beyond the expertise of the plant engineers, maintenance and operating personnel.

So, how is a pumping system, simple or complex, actually designed? Details of pump performance curves, types, pressure, power or efficiency are usually not on the horizon at this initial stage.

All the plant knows is their requirements. Maybe they want to pump 1,000 gallons per minute (gpm) from a cold water tank 2 miles away to a heat exchanger and return the water to the tank. Thus, the details of the pump will start to emerge.

1. Before talking about a pump, consider the pipe.

Velocity of liquid in pipes ranges between 3 to 10 feet per second (ft/sec). If the velocity is too slow, the dirt, sludge or other contaminants can settle. If flow is too fast, abrasive wear will reduce the life of the pipe. Plant designers are familiar with the specific concerns for each application. A sludge stream will have a larger pipe than a clean water application. But for a “nonexpert,” a good starting point could be, say, 5 ft/sec. Solving for pipe diameter (1,000 gpm, 5 ft/sec), we get d = 9.1 inches, so we round it to 10 inches to fit available pipe sizes. For now, we will not consider pipe schedule, wall thickness, etc.

2. Now that we have the pipe, pressure is the next step.

Pressure comes from friction and elevation. We will assume no elevation changes along the pipe run. Friction losses are determined from a well-known Moody Diagram, from which a friction coefficient is found and then friction losses (h) are calculated (see Image 1).

This is the friction loss a pump pressure would need to work against.

The Moody Diagram has lots of helpful information on it: Reynolds number (Re), pipe type/age, roughness, and thus friction coefficient, as seen on Image 1, may range from 0.01 to 0.1, potentially an error. Fortunately, some of this can be simplified.

Re = 5 ft/sec x (10/12) (ft) / 10-6 = 4 x 106 – i.e. turbulent region and, from Image 1, we already cut down the friction factor to start from at least 0.2. If we reduce this region from the rough pipe and super smooth pipes, we find that an average will be around f = 0.03 for an iron pipe of 10 inches diameter.


>>Read more.

 


A Complete Line of Pumps for Industry

Vertiflo Pump Company’s Vertical Sump Centrifugal Pumps, Horizontal End Suction Centrifugal Pumps and self-priming pumps are delivered fast, usually in half the typical lead time. Vertiflo’s vertical sump pump line offers up to 3000 GPM, 250′ Heads and 26′ depth. The horizontal end suction pump line offers up to 3000 GPM and 300’ Heads.

Vertiflo pumps are designed for nonresidential applications and currently over 20,000 are operating successfully worldwide. Vertiflo is recognized as a quality manufacturer of dependable pumps, and continues to grow and encompass new applications in the pump industry.

Horizontal End Suction Pumps

Back to Basics: Pump Types – End Suction Vs. Double Suction

There are often multiple pump types (Table 1) that can be selected for the same water application, with each pump type having its own strengths and weaknesses. This column tries to help guide the reader in the selection of the best pump type that will yield the greatest reliability and lowest life cycle cost for a specific application.

Excerpt from the WaterWorld August 2011 issue by Allan R. Burdis

End Suction Water Pumps

An end suction water pump would probably have the lowest initial cost for most applications, with reasonable efficiency. However, these pumps do not follow any standards, especially with regard to bearing life, shaft seal housings and dimensional interchangeability. They are also typically constructed with the lowest cost materials, such as cast iron casings with bronze or brass impellers. The impellers are typically of closed construction, without replaceable casing or impeller wearing rings. Further, there is typically more deviation from published performance, such as efficiency, for this pump type.

Rotary Pump Power

For non-critical, intermittent service applications these pumps may be the best choice. However, for critical applications, requiring long operating life, the cost of maintenance and down time may far exceed any initial cost savings.

 

End Suction ANSI/ASME B-73 Pumps

Chemical pumps (figure 1), which can handle corrosive, and/or toxic liquids and slurries, are available in a variety of configurations and materials. Pumps used in this industry are different from those used in other industries, primarily in the materials of construction and the many mechanical shaft seal configurations available. These pumps must also meet the American Society of Mechanical Engineers ANSI B73 standards, which require dimensional interchangeability, minimum bearing life, and many other quality specifications. The minimum casing material is ductile iron, with stainless steel being quite common. Typical construction is an adjustable open impeller, which is also good at handling entrained air.

Because of these upgraded features, reliability focused users will typically select an ANSI/ASME B-73 pump over a lower cost water pump for other critical applications, including water services.

Read More


A Complete Line of Pumps for Industry

Vertiflo Pump Company’s Vertical Sump Centrifugal Pumps, Horizontal End Suction Centrifugal Pumps and self-priming pumps are delivered fast, usually in half the typical lead time. Vertiflo’s vertical sump pump line offers up to 3000 GPM, 250′ Heads and 26′ depth. The horizontal end suction pump line offers up to 3000 GPM and 300’ Heads.

Vertiflo pumps are designed for nonresidential applications and currently over 20,000 are operating successfully worldwide. Vertiflo is recognized as a quality manufacturer of dependable pumps, and continues to grow and encompass new applications in the pump industry.

Pump Specific Speed

5 Must-Read Articles About Pump Efficiency

Pump efficiency is a fundamental concern for every end user. A thorough understanding of the definition of efficiency and what factors affect it can help operators and engineers optimize equipment design and operation. The five articles listed below are some of Pumps & Systems most well-read resources that outline efficiency concepts every end user should know.

Excerpts from Pumps & Systems

1. Centrifugal Pump Efficiency—What Is Efficiency?

Efficiency is simply how well a machine can convert one form of energy to another. If one unit of energy is supplied to a machine and its output, in the same units of measure, is one-half unit, its efficiency is 50 percent. As simple as this may seem, it can still get a bit complex because the units used by our English system of measurement can be quite different for each form of energy. Fortunately, the use of constants brings equivalency to these otherwise diverse quantities.
>>Read more.

2. Centrifugal Pump Efficiency—Specific Speed

As Terry Henshaw stated in “Centrifugal Pump Specific Speed”, the definition of specific speed can be confusing. It is best to think of it as an index number that can predict certain pump characteristics. Viewed this way, specific speed can be useful when selecting a pump for a particular application and predicting premature failure due to off best efficiency point (BEP) operation.
>>Read more.

3. The Power of Wear Rings Part Two: Efficiency

For decades, pump designers have known that increasing wear ring clearance leads to a loss of efficiency. However, with metal wear rings, even the minimum clearance as specified by API610 is substantial. Because the clearance cannot be reduced between two metal rings without an increased risk of pump seizure, metal wear rings limit pump efficiency.
>>Read more.

efficiency gain

4. Pumps: HP, RPM and Energy Efficiency

Reduced operating speed translates into less bearing wear and longer motor life. Longer pump seal life is achieved and the damaging effects of abrasives in the recirculated water are reduced. Less wear and longer life means a reduction in maintenance costs and system downtime.
>>Read more.

5. Gain Efficiency with Volute Design

The volute serves a simple purpose in radial machinery: to transfer flow from an annular cross section to an exit pipe. Of course, there are many variations on the theme. The process is reversed for turbines, where more than one exit or inlet to the volute may exist, and many other arrangements are possible.
>>Read more.


A Complete Line of Pumps for Industry

Vertiflo Pump Company’s Vertical Sump Centrifugal Pumps, Horizontal End Suction Centrifugal Pumps and self-priming pumps are delivered fast, usually in half the typical lead time. Vertiflo’s vertical sump pump line offers up to 3000 GPM, 250′ Heads and 26′ depth. The horizontal end suction pump line offers up to 3000 GPM and 300’ Heads.

Vertiflo pumps are designed for nonresidential applications and currently over 20,000 are operating successfully worldwide. Vertiflo is recognized as a quality manufacturer of dependable pumps, and continues to grow and encompass new applications in the pump industry.