TLDR
- A centrifugal pump is dimensioned as part of a hydraulic system, both from a hydraulic and mechanical point of view, to avoid maintenance costs, fluid losses and plant downtime.
- Flow rate and total head require knowledge of the amount of liquid and the release distance, including losses due to friction, valves, reductions, and curves.
- Nature, concentration and fluid temperature guide the choice of materials; density and viscosity determine the engine power and cutting performance impeller.
- The pump should operate near the peak efficiency point (BEP), never at the extreme points of the Q-H curve, to limit vibrations, poor lubrication, and cavitation.
- magnetic drive pumps CDRs have a lifespan of about 10-15 years if used at the right point of operation, and many reach 25-30 years.
Index
What to consider when choosing the right pump for your application
When sizing a centrifugal pump, it is important to treat it as part of a hydraulic system and to size it correctly from both a hydraulic and a mechanical point of view. Installing a pump that does not suit its operating conditions can lead to problems that translate into maintenance costs, leaks of hazardous or expensive liquids and plant downtime.
Size a centrifugal pump among the countless options available, it can be very complicated, so it is good to identify first of all:
- the system pressure and the characteristics of the liquid: these are essential to ensure correct priming of the pump and the right configuration;
- an accurate estimate of the budget and purchase costs, taking into account how long the pump will actually be used: this avoids selecting an unsuitable, undersized or oversized product, with the resulting rise in operating costs.
Choosing a low-cost pump makes little sense if it then proves inefficient because it breaks down frequently or is expensive to maintain.
Key factors in correct pump sizing
From a hydraulic point of view, identifying the right centrifugal pump for the system means making sure that a few important factors have been considered.
The flow rate and total head of a pump
To know how to calculate the centrifugal pump flow rate it is necessary to know the amount of liquid that must flow into the pump and at what distance the same liquid must be re-pressurized within the system. In the total head calculation, it is essential to also consider any pressure losses related to fluid friction, the possible presence of valves, reductions, and elbow bends in the piping.
Which properties of the pumped liquid matter when choosing a centrifugal pump?
The main properties of the pumped fluid needed for correct pump selection are:
- The nature and temperature of the fluid determine the choice of pump materials. Each material has a different mechanical and chemical compatibility with the pumped liquid and a different resistance to the operating temperature. Knowing the type of liquid, its concentration and its temperature therefore makes it possible to select compatible materials.
- Fluid density and viscosity they influence the engine power to be selected and at the same time the correct sizing of the impeller cut, to ensure the achievement of the required performance.
- The presence of solid suspensions in the pumped liquid: this information is important for choosing the type of centrifugal pump to select.
The Magnetic drive centrifugal pumps are generally suitable for working with clean or lightly contaminated liquids.
CDR Pompe, thanks to its design team—which has decades of experience in the field of magnetic drive—has managed to overcome this limitation by developing the XTN and XTS pumps, magnetic drive pumps specifically designed for pumping liquids with high concentrations of solid suspensions.
Maximum pump efficiency and optimal operation
From a technical standpoint, it is advisable to run the pump ideally in the Best Efficiency Point (B.AND.P.) Efficient Point, that is, between 50 and 110% of the pump’s maximum efficiency point, and in any case never at the extremes of the Q-H curve. This operating point, in fact, minimizes vibrations, insufficient lubrication, and cavitation, and therefore breaks of the pumps themselves.
CDR can offer solutions to safeguard pump operation even in operating conditions far from the BEP, for example by configuring the pump through the installation of bushings with a special surface treatment.RunSafe SICself-lubricating and capable of counteracting poor lubrication.
Another deciding factor: maintenance cost
A relevant role in Choosing the ideal pump it is also covered by the cost of maintenance of the same in the medium-long term, not just the purchase cost. CDR magnetic drive pumps, especially when compared to mechanical seal pumps, are in fact simple to dismantle and reassemble and, if used at the right operating point, achieve a Useful life of approximately 10/15 years (hundreds of CDR pumps installed can easily reach 25/30 years of service).
Contact us In case of doubts about the sizing of the centrifugal pump for your application. Our sales representatives, thanks to their experience, are able to assist you in choosing the right ideal pump, discussing the various aspects listed above and delving into the details of each specific application.
Frequently Asked Questions
What hydraulic factors should be considered to properly dimension a centrifugal pump?
The main hydraulic factors are flow rate e total head. It is necessary to know the amount of liquid to be moved and the distance at which it has to be re-pumped. In calculating total head the flow rate, the load losses due to the fluid’s friction, valves, reducers and elbow bends on the pipes must be included.
How do the characteristics of the liquid affect the choice of a centrifugal pump?
The characteristics of the liquid determine the material, the engine, and the type of pump. Nature, concentration, and temperature define the chemical and thermal compatibility of the materials. Density and viscosity affect the engine power and cutting performance impeller. The presence of solid suspensions guides the choice of the type of centrifugal pump.
What is the BEP of a centrifugal pump and why is it important to work close to that point?
The BEP (Best Efficiency Point) is the maximum efficiency point of the pump. It is recommended to work between 50 and 110% of this point and never at the extreme points of the Q-H curve. In this way, vibrations, poor lubrication and cavitation are minimized, and thus the risk of breakdowns is reduced to a minimum.
magnetic drive Can a pump pump liquids with suspended solids?
They magnetic drive pumps are generally suitable for clean or slightly contaminated liquids. However, it CDR Pompe has developed XTN the XTS models magnetic drive pumps designed to pump liquids with solid suspensions at high concentrations, overcoming this typical limit of the technology.
How can a pump be operated away from its maximum efficiency point without damaging it?
The pump can be configured with sleeves equipped with the RunSafe SIC self-lubricating surface treatment. This CDR solution counteracts the poor lubrication typical of operation away from the BEP and safeguards pump operation, although working near the point of maximum efficiency remains preferable.
How long does a pump last magnetic drive and how does maintenance affect the total cost?
A magnetic drive CDR pump, used at the right point of operation, has a lifespan of approximately 10-15 years, and hundreds of installed pumps reach 25-30 years of service. Compared to traditional mechanical seal pumps pumps, they are easier to disassemble and reassemble, reducing maintenance costs in the medium-long term.