Posted on Mar 4, 2020
A commercial pump is normally pump equipment that moves fluids-state substance by its mechanical action for commercial applications. Pumps can be categorized into three major models based on the method those pumps exploited to move the target fluids.
All these three models are determined by the way they move fluids, and there are direct lift, displacement, and gravity methods. That is, there are direct lift pump, displacement pump, and gravity pump respectively. Commercial Pumps are typically operated by either typically reciprocating or rotary mechanisms, and consume energy to perform mechanical work moving the fluid, rendering the liguid transmission performance. Commercial Pumps can also be classified in another way. That is, submerged in the fluid in which they are pumping or be placed external to the fluid. Besides, pumps can be categorized by their method of displacement into positive displacement pumps, impulse pumps, velocity pumps, gravity pumps, steam pumps and valve-less pumps. Besides, there are two basic types of pumps, that is, positive displacement and centrifugal. These types of classifications are used in both theoretical and commercial pump manufacturing, while in the commercial usages, the main purpose is for industrial usages.
Generally speaking, a pump can operate through many power sources, such as onsite operators’ manual operations, or by electricity, or engines, or even sustainable energies such as wind power. Those energy sources can be a wide variety of equipment which comes in any sizes, from microscopic for use in medical applications to large industrial pumps for waterworks, or ordinary size industrial pump for machine tool coolant transmission as well as cutting liquids. Commercial Pumps serve in a wide range of applications such as pumping water from conventional wells, aquarium filtering duty, pond filtering tasks, 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 or other similar objects.
In the machine tool sectors, pumps are used to move cutting liquids, coolants, etc. Therefore, pumps are considered a necessary component rather than an optional component of a machine tool when manufacturers are building machine tools, making it a crucial part of the machinery. The coolant and cutting liquid density is a crucial variable for choosing the pumps, users must know those combinations and make the right choice about this. In addition, the number of impellers determines decisively the way the pump works and the strength for liquid moving. If, for example, there is a pump that contains only one revolving impeller, it is called a single-stage pump. If a pump contains two or more revolving impellers, it is called a double- or multi-stage pump. In the application of biology sector, many different types of chemical and biomechanical pumps have evolved; BIOMIMICRY is sometimes used in the development of new types of mechanical pumps. Just like in the early days people tried to study birds in order to enable human flight.
Regarding the categorization introduced above, a positive displacement pump makes a fluid move by trapping a fixed amount and forcing that trapped volume of liquid into the discharge pipe. Usually, some positive displacement pumps use an expanding cavity on the suction side, and a decreasing cavity on the discharge side. With the method, liquid flows into the pump as the cavity on the suction side expands and the liquid flows out of the discharge when the cavity collapses. The volume is constant through each cycle of operation. A positive displacement pump can produce the same flow at a given speed no matter what the discharge pressure. As a result, positive displacement pumps are constant flow machines. At the same time, however, a slight increase in internal leakage as the pressure increases prevents a truly constant flow rate. That is to say, a positive displacement pump must not operate against a closed valve on the discharge side of the pump, as it has no shutoff head like centrifugal pumps and other similar objects.
Accordingly, positive displacement pumps operating against a closed discharge valve continue to produce flow and the pressure in the discharge line increases until the line bursts, the pump is severely damaged. For safety concern, a relief or safety valve on the discharge side of the positive displacement pump is thus necessary, and both manufacturers of pump and users in the industry shall be careful of this issue. The relief valve can be either internal or external. On the contrary to the centrifugal pumps, a positive displacement pump can produce the same flow at a given speed no matter what the discharge pressure. As a result, positive displacement pumps are constant flow machines. At the same time, however, a slight increase in internal leakage as the pressure increases prevents a truly constant flow rate. As a result, a positive displacement pump must not operate against a closed valve on the discharge side of the pump, since it has no shutoff head like centrifugal pumps. In sum, positive displacement pumps operating against a closed discharge valve continue to produce flow and the pressure in the discharge line increases until the line bursts, the pump is severely impacted.