What is S.G.?
Specific gravity, the ratio of the density of a substance to that of water.
What is gauge pressure if the gauge reads 20 psi?
20 psig
What is the absolute pressure if the gauge reads 20 psig?
34.7 psia
20+14.7
What is head pressure?
The height in feet of a column of water that is one foot square at the base.
What is the formula for head pressure?
Psi= ft x 0.433 x S.G.
What is vapour pressure?
Pressure at which a liquid flashes into a vapour (boil) at a given temperature.
What is cavitation?
When the pressure of a liquid is reduced to or below it’s vapor pressure, small bubbles or pockets of vapor called cavitation begin to form as these vapor bubbles move to regions of higher pressure they collapse ore implode.
What is aeration?
Where a partial vacuum is created at the pump inlet, which can draw in air and reduce the pumps capacity.
What is Bernoulli’s principle?
That as a liquid or gas passes through a pipe, if it comes to a larger section of pipe the velocity will decrease while the pressure increases.
What is velocity head?
Energy in a system due to the liquids velocity.
What is friction head?
The friction the liquid has while passing through the pipes reducing the amount of head or pressure available.
What is suction head?
When the level of the supply liquid is above the centreline of the pump.
What is a positive suction head?
It means the weight of the liquid and the atmospheric pressure are able to push the fluid into the pump.
What is total suction head?
Is the static suction head on the pump suction line above the pump centreline minus all the frictional losses.
What is suction lift?
Where the supply reservoir is located below the pump.
What is static discharge head?
The vertical distance from the centre of the suction eye to the surface of the liquid in the discharge tank.
What is total head?
The measure of the work the pump foes to raise the liquid from the level in the suction tank to the level in the discharge tank for a given flow.
What is net positive suction head?
Suction head in feet absolute above the vapour pressure of the fluid at the pump suction.
What is the net positive suction head required? (NPSHR)
Amount of head used to overcome friction and increase the velocity of the fluid as it flows from the suction flange of the pump through the eye of the impeller and onto the vanes.
What are the 4 main categories of dynamic pumps?
- Radial-flow centrifugal pumps
- Axial-flow pumps
- Mixed-flow pumps
- Peripheral pumps
How does a radial-flow centrifugal pump work?
The water that flows through the centre of the impeller follows the path dictated by the blades in the casing. The centra fugal force flings it outward so it gains velocity. The liquid then enters the collector, a casing that surrounds the impeller, which slows the liquid to a useable velocity and converts the kinetic or velocity energy into pressure energy.
The 2 basic forms of the collector are the volume and the diffuser.
Characteristics and main parts behind an axial-flow pump?
- No radial component to the discharge from its impeller.
- Produces it’s head by the pushing action of the vanes on the liquid.
- No change in the direction of flow, which moves through the purple like casing parallel to the shaft.
- Relatively low discharge head but produces large flow.
Characteristics and main idea of a mixed-flow pump?
- Have both radial and axial components to the discharge from there impellers.
- Develops it’s discharge by using centrifugal force and the lifting action of the vanes on the liquid.
Characteristics and types of peripheral pumps?
- High speed pumps
- Run at extremely high speeds.
- liquid enters the eye of the impeller and makes a number of rotations within the forced vortex. The orbits gradually increase until the liquid exits the concentric housing and the diffuser nozzle that converts that velocity head into the head pressure.
- Regenerative turbine pumps
- Relatively high heads and low flow applications
- Generally a solid disk with a double row of straight cut or impulse type buckets cut around his periphery
