A pump is a device that moves fluids (liquids or gases), or sometimes slurries, by mechanical action, typically converted from electrical energy into hydraulic energy. Pumps can be classified into three major groups according to the method they use to move the fluid: direct lift, displacement, and gravity pumps.
Pumps operate by some mechanism (typically reciprocating or rotary), and consume energy to perform mechanical work moving the fluid. Pumps operate via many energy sources, including manual operation, electricity, engines, or wind power, and come in many sizes, from microscopic for use in medical applications, to large industrial pumps.
Mechanical pumps serve in a wide range of applications such as pumping water from wells, aquarium filtering, pond filtering and aeration, in the car industry for water-cooling and fuel injection, in the energy industry for pumping oil and natural gas or for operating cooling towers and other components of heating, ventilation and air conditioning systems. In the medical industry, pumps are used for biochemical processes in developing and manufacturing medicine, and as artificial replacements for body parts, in particular the artificial heart and penile prosthesis.
The most commonly used pump is definitely water pumps, therefore there are lots of types of pumps for underwater usage like Submersible Pump
When a casing contains only one revolving impeller, it is called a single-stage pump. When a casing contains two or more revolving impellers, it is called a double- or multi-stage pump.
Pump research and development efforts are primarily driven by the needs of the customer. Today, these needs are centered around cost and reliability issues with the understanding that certain threshold levels of performance are achieved. As centrifugal pumps have reached high levels of maturity in most industrial applications, we can anticipate, that in the future, customer expectations will change subtly but significantly. They will demand continuously reducing costs with the understanding that reliability and technology needs will be satisfied. This would lead to a strong emphasis on consistent predictability of performance in the field and to less of a focus on innovations in design. R&D efforts in the past were intended to stretch the envelope to produce better hydraulic performance, to improve mean-time-between-failures, and to operate at higher speeds. In contrast, R&D efforts in the future would be aimed towards cost reduction, accurate hydraulic, guarantees, and flawless performance in the field. In this paper, the R&D efforts of the past, present, and future are discussed in terms of three core competencies, which are essential for today’s pump manufacturer. These are hydraulics (with an emphasis on improving predictability of performance and improving impeller life), vibrations (with a view to providing cost effective problem solving/avoidance capability), and pump designs which capitalize on improved understanding of the underlying technologies.
