Classification and Selection Methods of Water-Saving Irrigation Pumps for Farmland
Agriculture cannot do without water, so it also cannot do without pumps. Different regions have different choices, so how are water-saving irrigation pumps for farmland classified and selected?
There are mainly three major categories of agricultural water pumps to choose from: mixed-flow pumps, centrifugal pumps, and submersible pumps.
Agricultural mixed-flow pumps. The flow rate and head of a mixed-flow pump fall between those of a centrifugal pump and an axial-flow pump. It is small in size, light in weight, highly efficient, and has a wide high-efficiency range, with a simple structure, convenient use, and easy maintenance. The conveyed medium is clean water or similar to clean water, making it suitable for farmland drainage and irrigation as well as industrial water supply and drainage.
A mixed-flow pump is a type of pump between a centrifugal pump and an axial-flow pump. It has a large water output but a relatively low head, making it suitable for areas in the south with abundant surface water sources. A common model is the HW-type mixed-flow pump, which can be powered by an electric motor or a diesel engine.
Various forms of mixed-flow pumps can also be developed according to user requirements (such as vertical type, mechanical seal, special materials, etc.), and users can change the pump speed within a certain range according to specific usage requirements.
Agricultural centrifugal pumps
A centrifugal pump works by using the rotation of an impeller to make water undergo centrifugal motion. There are many models to choose from, and the selectable ranges of flow rate and head are also wide, making it the most widely used water pump in agriculture. In plains areas, a centrifugal pump with a lower head can be chosen; in hilly areas, one with a moderate head can be chosen; and in high-altitude areas, a multistage centrifugal pump with a higher head can be used. Users should make their purchase according to the local terrain, water source, and lifting height. Common models include: IS-type centrifugal pumps, ISW horizontal centrifugal pumps, B-type centrifugal pumps, BA-type centrifugal pumps, S/SH-type double-suction centrifugal pumps, and D/DG-type multistage centrifugal pumps.
Agricultural submersible pumps
Submersible pumps are suitable for pumping water from deep wells: they are mainly used for farmland irrigation and irrigation in plateau and mountainous areas, and are mainly used in plain areas lacking surface water such as North China. The common model is mainly: QJ-type deep well submersible pumps.
1. The submersible pump motor and pump are integrated and operate submerged in water, making them safe and reliable.
2. There are no special requirements for the well pipe and discharge pipe (that is: steel pipe wells, ash pipe wells, earth wells, etc. can all be used; under permissible pressure, steel pipes, rubber pipes, plastic pipes, etc. can all be used as discharge pipes.
3. Installation, use, and maintenance are convenient and simple, the floor area is small, and no pump house needs to be built.
4. Simple structure, saving raw materials.
5. Whether the conditions for using a submersible electric pump are suitable and whether management is proper are directly related to its service life.
After customers determine the type of agricultural water pump, they should consider its economic performance, with particular attention to the selection of the pump's head and flow rate and its matching power. It must be noted that the head (total head) indicated on the pump nameplate is different from the outlet head during use (actual head), because there will be a certain resistance loss when water flows through the delivery pipe and near the pipeline. Therefore, the actual head is generally 10%— 20% lower than the total head, and the water output is correspondingly reduced. Therefore, in actual use, it can only be estimated at 80% to 90% of the head and flow rate indicated on the nameplate. For the selection of the pump's matching power, it can be selected according to the power indicated on the nameplate. In order to make the pump start quickly and be safe to use, the power of the prime mover can also be slightly greater than the power required by the pump, generally about 10% higher, which is appropriate; if power is already available, when purchasing a pump, one can purchase a pump matching it according to the power of the prime mover.