The piston pumps are volumetric operating machines whose purpose is to move a fluid inside a plant or hydraulic system. The displacement of the fluid takes place through the connecting rodcrank mechanism: this mechanical system transforms the rotary movement of the crankshaft into reciprocating movement of the pistons which, during their stroke, open and close the volumes inside the cylinder. The shaft-connecting rod-piston assembly represents the mechanical heart of the pump and finds accommodation, supported by two main bearings, inside the pump body. The latter, in addition to playing a structural support role, also serves as an oil container necessary for the lubrication of the mechanical parts. The hydraulic part of the pump is represented by the head and its components: valves and gaskets. The valves are two for each cylinder and are arranged one in opposition to the other on both the suction and delivery sides, opening and closing according to the movement of the piston ensure the correct passage of the fluid and guarantee directionality. In fact, the piston pumps are not affected by the rotation direction of the shaft. The gaskets, fitted with suitable bushings on the piston seats, prevent the fluid from leaking out of the pump.
• Piston pumps are mainly used when there is a need to use a fluid at high pressures. They deliver
an instantaneous flow rate that is not constant and is affected by the single piston pumping. The
greater the number of pistons, the greater the regularity of the flow. Most of the pumps have
three pistons as this configuration has the best compromise between dimensions and pulsations.
• The pumps can be used at different speeds: being volumetric machines, the greater the speed the greater the flow rate will be. It is necessary to avoid too low or too high speeds both for reasons related to the volumetric efficiency and for problems related to the dynamic behavior of the seals and the mechanics.
• They can be powered either from a network or from a tank; in the latter case, however, it is not recommended to run the pump with a suction pressure below -0.25 bar.
• As their function is to provide a flow rate and not a pressure, they require the use of a nozzle / choke to pressurize the fluid and a safety or regulation valve to ensure that the system does not exceed the maximum pressure the pump is designed for.
• For special applications, such as hot water or use with aggressive fluids, pumps have been developed with appropriate technical devices such as PTFE or Viton seals, heads and parts in contact with the stainless steel fluid, etc.
Annovi Reverberi pumps general features
• FORGED BRASS
Can be coupled with various types of motors (electric, gasoline, hydraulic) directly or with flexible coupling.
PISTON AT THE TOP DEAD CENTER (TDC)
The piston is in its maximum stroke and occupies all the volume of the cylinder. The valves are both closed and there is no fluid passage.
START OF SUCTION CYCLE
The piston starts its run towards the bottom dead center (BDC). During the displacement, the volume of the cylinder increases and a depression is created which allows the opening of the intake valve while keeping the delivery valve closed. The fluid starts flowing inside the cylinder.
PISTON AT THE BOTTOM DEAD CENTER (BDC)
The piston has been recalled completely and is at the lowest point of its stroke. The valves are both closed while the cylinder is filled with fluid.
START OF PRESSURE CYCLE
The piston has reversed the motion and starts its run towards the top dead center (TDC). During the movement of the piston the volume of the cylinder starts to decrease and the fluid pressure increases. The pressure opens the discharge valve and allows the fluid to flow out of the cylinder to the delivery manifold. The suction valve is kept closed by pressure.
Valvole di aspirazione e mandata con passaggi acqua maggiorati.
Intake and delivery valves with oversized water passages.
Sistema di tenuta a doppia guarnizione.
Double gasket sealing system.
Anelli tenuta olio con doppio labbro.
Oil seal rings with double lip.
Pistoni in ceramica di grosso spessore per una maggiore durata.
Extra-thick ceramic pistons for greater durability.
Cuscinetti a rulli conici di qualità e sovradimensionati.
Top quality, oversized tapered roller bearings.
Albero sovradimensionato e con terminale lungo per una migliore trasmissione della coppia, in acciaio stampato e trattato termicamente per garantire elevata resistenza meccanica.
Oversized shaft with long end section for better torque transmission, in forged steel and heat treatment to ensure high mechanical resistance.
Pistoni di guida sovradimensionati e rettificati per una riduzione dell’attrito durante lo scorrimento ed una migliore tenuta olio.
Oversized piston guides for smoother stroke and better oil seal functioning.