A screw pump, also called a screw pump, is one of the varieties of rotary gear type devices. In it, the pressure of the injected liquid is formed due to its displacement by helical rotors rotating inside the stator. There may be one or more, depending on the configuration of the device. Screw pumps are easily obtained from gear pumps, and this is done by increasing the inclination of the teeth in them, as well as reducing the number of teeth on the gears. However, it is better to use the "original version" of the device.
The screw pump works according to the following principle. The pumping of liquid is carried out due to the fact that it moves between the helical grooves and the surfaces of the housing. The grooves are along the axis of the screw. With their protrusions, they "walk" along the replaceable grooves, which prevents the liquid from moving back.
The screw pump is used in a fairly wide range. It can be useful for transferringgas, steam, as well as their mixtures or liquids having different degrees of viscosity. They were first put into production back in 1936. Due to the simplicity of their design, they can freely operate even in the presence of mechanical impurities that have viscous fluids at a pressure level of up to 30 MPa. Such characteristics are very important for solving a wide variety of tasks. Entire installations of screw pumps are actively used in wells intended for the extraction of methane from coal seams, as well as for pumping water from there. They are used to extract oil, water, and other wells.
The screw pump has interesting design features. To increase the quality of seals, as well as to reduce the number of leaks in this type of fixture, it is customary to use cylindrical or conical elastic housings. The conical screw is pressed by the spring very reliably, in addition, the pressure of the pumped liquid plays its role here, which significantly reduces the number of leaks. Pumps with a metal case are able to withstand significantly higher loads than their counterparts placed in elastic cases. A device with a conical screw can work well in a hard case.
The most common screw pump is the three screw pump. In practice, its scope turned out to be the widest. This is due to certain characteristic advantages of this type of equipment:
- uniform supply of substance;
- the ability to pump liquids containing solid additives withoutany damage;
- Possibility for self-priming of liquids;
- high outlet pressure can be obtained without the mass of injection stages characteristic of other types of pumps;
- when working, the device creates noise effects at a fairly low level;
- The pump mechanism is very well balanced.
This species also has certain disadvantages, which are much less than advantages:
- a fairly high degree of complexity in the manufacture of this type of equipment, as well as its high cost;
- no possibility of working volume regulation;
- idle use is simply unacceptable.
