Reciprocating pump
A reciprocating piston pump (also known as a reciprocating displacement pump , colloquially also referred to by the ambiguous abbreviation piston pump ) is a displacement pump in which the displacer (piston) executes a stroke movement, i.e. a straight ( translational ) movement.
Working principle
A reciprocating piston pump usually consists of a piston that runs in a cylinder , combined with an inlet and an outlet, each of which is closed by a valve .
In the first stroke, during suction, the piston moves to the right in the picture below. The inlet valve opens and the fluid flows into the cylinder. In the second cycle, during the conveying movement, right picture, the inlet valve closes and the piston moves back. The outlet valve opens and the pumped medium is pressed out.
history
Even ancient cultures such as the Romans had reciprocating pumps for pumping water.
The Turkish-Ottoman polymath Taqi ad-Din , who lived in the 16th century, described in one of his books a complex piston pump with six cylinders, counterweights and check valves that were controlled and driven by a central camshaft . The pump was driven by water power and served as a pumping station .
The use of piston pumps to pump air was first successfully practiced by Otto von Guericke in 1649 and served him when attempting the Magdeburg hemispheres to create a technical vacuum.
The importance of the use of piston pumps has shifted since the 19th century. With the introduction of the centrifugal pump , the use of the piston pump for pumping large volumes or contaminated liquids ( drinking water , waste water ) decreased. The principle of piston pumps is used, for example, in metering pumps , hand-operated conveyor systems or for producing high pressures.
Areas of application
Like other pumps , reciprocating pumps can also be used to convey liquids or gases , with gases also being compressed in the process.
Piston pumps can achieve high pressures when pumping liquids. In addition, the volume of liquid delivered can be precisely determined ( dosing pump ). The drive can be done by hand (e.g. hand-operated handle pump ), electromagnets or motors.
Agriculture
In liquid manure technology, the piston pump is used in a mobile or stationary version, depending on the location. The disadvantage of piston pumps is the flow pulsation inherent in the principle, which can lead to intense pressure oscillations (pressure pulsations) or mechanical oscillations in the connected line system. In the case of larger flow rates, several cylinders, which work offset, are provided. Alternatively, pulsation dampeners filled with gas or liquid can be used.
Examples
Priming piston pump
In scoop pumps, the outlet valve is located in the piston itself. As a result, the material to be pumped is transported to the other side of the piston in the pushing-out cycle and pushed out from there in the subsequent suction cycle, while new material is simultaneously sucked in on the other side of the piston. This type of pump is suitable for pumping highly viscous material and is often used in drum follower plate pumps . Dosing pumps are based on the principle of the piston pump.
Many soap dispensers are based on the principle of a piston pump. The two pictures show an example. The piston (3) is slidably seated on the axis (2) within the housing (4). The hollow axis continues into the soap outlet (1) on the side. When you press the head (1), the piston releases the inlet through the side holes at the lower end of the axle. At the same time, the spring (5), which is supported at the lower end in the housing, is tensioned. The soap pushes the ball (6) down and closes the inlet. When the button is released, the passage and closing functions of the valves are reversed. Soap is drawn in and fills the housing. Pressing it again presses the soap out of the dispenser.
Diaphragm pump
With a diaphragm pump , the pumped medium is sucked in or expelled through a diaphragm instead of a piston. A distinction is made here between mechanically linked diaphragm pumps and hydraulically linked diaphragm pumps (also: piston diaphragm pumps). With the latter, the membrane (typical materials are e.g. PTFE or steel) is subjected to pressure on both sides and has no external forces to support. With hydraulically linked diaphragm pumps, pressures of up to 3500 bar have already been achieved.
Piston pumps on steam locomotives
Steam-powered piston pumps are flywheelless steam engines in which the drive piston and working piston are keyed on a common piston rod. Piston pumps work at full pressure because there is no control device that could shut off the steam supply during the working movement, so that the expansion of the steam could be used. The reversal takes place at the end of the respective working stroke, which is why the steam escapes from the working area at operating pressure. This generates the working noise that is typical of these pumps and, if the damping is insufficient, whipping. In order to at least partially compensate for the disadvantage of the full pressure mode of operation , piston pumps have been developed which work with a compound effect . Once the steam has done its work in the smaller high-pressure cylinder, it is directed to the larger low-pressure part via the control of the pump, where it is further expanded and can release part of its thermal energy. Only after this second stage does the steam go outside via the exhaust or is fed to a preheating device in which further energy is extracted from the steam in order to preheat the boiler feed water. See also: duplex pump
In the working part of the pump, either air for the braking devices and other auxiliary devices is compressed or the piston pump conveys preheated feed water into the boiler. In the working part of the air pumps, too, a multi-stage mode of operation has often been implemented in order to improve efficiency.
There have been built units up to the double compound air pump, which consist of two parallel piston pumps.
Other designs
- The inline pump , a double piston pump, is a special type of piston pump in which two pistons in a sleeve take care of the pump clearance.
- Another variant is the vibration, oscillating armature or oscillating piston pump, which is also possible as a variation of a free piston machine .
- A bicycle - air pump is also a piston pump. The piston only seals the cylinder during the exhaust movement and thus takes over the task of the intake valve. The outlet valve is not integrated in the pump. This is why you cannot inflate a balloon with a bicycle pump. The valve of the bicycle tube acts as the outlet valve.
- The axial piston pump and the radial piston pump are further designs of piston pumps. With these two types of construction mentioned above, liquids, especially mineral oils and special liquids (e.g. HFA, HFC, HFD, drilling emulsion) are pumped. The field of application of such hydraulic pumps is broad: from machine tools, hydraulic travel drives (e.g. construction and agricultural machines) and test stands to wind turbines.
literature
- Klaus D Linsmeier, Achim Greis: Electromagnetic actuators. Physical principles, designs, applications. In: Die Bibliothek der Technik, Volume 197. Verlag Moderne Industrie, ISBN 3-478-93224-6
- Friedrich P. Springer: From Agricolas 'pomps, which pulled the water through the winds' to the rod pumps of the oil production, crude oil / natural gas / coal. October 2007, issue 10
Web links
- Animated model ( LEIFI )
Individual evidence
- ↑ Taqi ad-Din : Al-Turuq al-Saniya fi al-'ālat al-rūhaniya, page 38 ( Chester Beatty Library : Arabic MS 5232)
- ^ Salim Al-Hassani , Mohammed A. Al-Lawati: The Six-Cylinder Water Pump of Taqi al-Din: Its Mathematics, Operation and Virtual Design. In: muslimheritage.com , accessed July 28, 2016