Pump As the heart of the hydraulic system, the pump converts mechanical energy supplied by electric motors, combustion engines, or … into hydraulic energy.
In the hydraulic industry, pumps are divided into two general categories.
- Non-positive displacement pumps (hydrodynamic pumps)
- Pumps with positive displacement
Benefits of positive-displacement pumps (compared to non-positive-displacement types)
- Ability to operate at high pressures (up to 10,000 psi and above)
- Compact and small dimensions
- High volumetric efficiency
- Minor change of efficiency in design pressure range
- High flexibility (ability to perform a wide range of pressures and speeds required)
Positive displacement pumps are divided into three main types:
Gear Pumps (with fixed displacement)
A. External gear pumps
B. Internal gear pumps
C. Earring pumps
D. Screw pumps
E. Gyrator pumps
Vane pumps (with constant or variable displacement)
A. Unbalanced blade pumps (with constant or variable displacement)
B. Balanced blade pumps (fixed displacement only)
Piston pumps (fixed or variable displacement)
A. Axial piston pumps
B. Radial piston pumps
The number of pumps generally depends on the amount of tolerances and precision used in the manufacture, mechanical condition of the components and pressure balance. In an ideal pump, the coupling between the involved components is assumed to be zero. In practice, the slugs should be as small as possible to allow a thin film of oil to lubricate the sliding components.
Overall pump performance is calculated by comparing the available power output and power consumption at the input and divided into volume and mechanical efficiency.
– Volume Volume indicates leakage at the pump. This is the case where the pump is in design tolerances, operating conditions and design pressures.
-Mechanical twelve indicates the amount of energy loss due to factors such as friction in bearings and components, as well as turbulence in the fluid. The mechanical efficiency of the pumps is usually between 90 and 95 percent.
– Total efficiency indicates total energy loss and is equal to the product of volume and mechanical efficiency.
Pump Selection Criteria
– The maximum working pressure
– Capability of access and replacement of components
– Maximum Output Flow
– Maintenance and spare parts
– Type of Control
– Stimulant speed
– The type of fluid
– Size and weight
– Translations needed
In order to protect the pump against cavitation and to keep the pressure higher, fluid saturation pressure at the pump inlet requires the following materials:
1. Consider a suction line speed of less than 5 ft / sec.
2. Select pump inlet lines even as short as possible
3. Use minimum connections to the input line
4. The pump may even be installed near the tank.
5. Use low pressure filters and contamination indicators to replace when dirty.
6. Use appropriate oil as recommended by the manufacturer.