2 - tea water services - pump training final mf

© TEA. www.tea.ie 1

Pumping Technology


• Pump Types

• Pump Selection Parameters

• Performance Curves

• Variable Speed

• Motor Efficiency

• Pipe Design

• Control Systems

Agenda


• Positive Displacement Pump

• Progressive Cavity – Mono or Seepex.

• Rotary Lobe Pump

• Centrifugal Pump

• End suction

• Multi-Stage vertical and horizontal

• Split Case

• Unlike positive displacement pumps , centrifugal pumps deliver a variable flow rate Q (increasing with decreasing head H) when operating at constant speed.

Pump Types


Progressive Cavity Pump


How do Progressive Cavity

Pumps work?

• When the rotor and stator

are combined cavities are

created

• As the rotor rotates these

cavities are progressed

through the pump stator

• Two complementary cavities

are formed, as one is finishing

the other is beginning

• This results in an

uninterrupted continuous flow


Progressive Cavity Pump


Rotary Lobe Pump


End Suction Centrifugal

Pump


Centrifugal Pump


• Runs at fixed speed (electrical frequency of

power)

• Flow will be determined by resistance to flow

(head).

• Motor will supply as much or as little power

as is required to maintain fixed speed (within

capabilities).

• Power consumed based on pump curve.

Centrifugal Pump


End Suction Centrifugal

Pump


Centrifugal Pump Impeller


Mechanical Seal


Multi-Stage Pump


Horizontal Multi-Stage

Pump


Split Case Centrifugal

Pump


Vertical Multi-Stage Pump


Submersible Borehole

Pump


Submersible Sewerage

Pump


Pump Selection Parameters


Pump System

Reservoir

Source

Motor (4)

Key components to be dealt with individually:

1. Pump

2. Motor

3. Pipework

4. Rising main

Pump: impellor &

stator only (1)

Pipework

(Pumphouse &

Rising Main) (3)


Energy in pumping

Motor losses

Real work

Done

Pipe losses

Pump losses

Typical Energy efficiency of a pump set today


Flow

Flow means the quantity of liquid to pass

across a surface, such as the delivery flange

of a pump or a cross section of a pipe, in a

unit of time.

• Gallons per minute (gpm)

• Litres per minute (I/min)

• Litres per second (I/s)

• Cubic metres per hour (m3/h)


Head

• Head means height, difference in level or gradient.

• A pump has a flow of 10 litres per second and a

head of 30 metres, this means that the pump is

capable of raising 10 litres of liquid through 30

metres every second.

• The pump will achieve this head no matter what

liquid is being pumped. This means that the pump

will lift water, petrol, mercury, etc. and only the

power demand on the motor will have to be

different.


• Static Head: This is the vertical height from the

water level at the intake to the highest point to

which the water is to be delivered.

• Friction Head: This is the head generated

through losses generated in the rising main,

suction pipework and valves.

• Counter Pressure: Pressure head requirements

in water softeners, pressure filters, control

valves, etc.

Head


Friction Head / Head loss

• Head loss is that part of the head, possessed by

the liquid, which is lost in passing through a

pipe, valve or filter.

• This loss is not recoverable as it is lost due to

friction.

• The head loss is proportionately greater as the

speed of the liquid increases.

• So the more the flow is restricted by scaled

pipes, clogged filters, partially closed valves etc.

the greater the head loss will be.


Pipe Losses

Reservoir

Source

Motor (4)

Real

work

Done

Pipe

losses

Pump

losses

Motor

losses


Rising Main Friction

Losses

3 KM Rising Main Flow - 60 m³/hr

• 200mm dia. Friction = 0.13m/100m (0.5m/s)

• 150mm dia. Friction = 0.6m/100m (0.9 m/s)

• 100mm dia. Friction = 4.5m/100m (2.1 m/s)

• 200mm pipe = 3.9m (energy cost = €3/day)

• 150mm pipe = 18m (energy cost = €14/day)

• 100mm pipe = 135m (energy cost = €105/day)


System Curve


Suction Lift

The Suction Lift calculations includes:

• The vertical height difference from the water level in the

sump to the centre of the pump suction flange.

• Losses in suction pipework and footvalve.

• Flow velocity at pump inlet.

• Liquid vapour pressure.

• Atmospheric pressure

This calculation provides the Nett Positive Suction Head

available from the system. NPSHa


N P S H a

Pi = Surface pressure of fluid (N/m2)

Pb = Barometric pressure (N/m2)

Pv = Vapour pressure of fluid (N/m2)

ρ = Fluid density (kg/m3)

Ve = Velocity of fluid at pump inlet (m/s)

Ze = Fluid Surface level above pump inlet. (m)

Fe = Friction loss is pipe to pump. (m)

The Pump Manufacturer provides the NPSH required by the

pump. If the NPSHa is less than the NPSHr cavitation will occur.


Cavitation

• Cavitation is the vapourisation of liquid caused by the

pressure dropping below its vapour pressure at the impeller

inlet.

• As liquid flows from the pump inlet flange into the impellor the

head initially falls as the velocity of the fluid is

increased. This drop in head may be sufficient to cause the

liquid to boil. This results in "cavitation".

• Cavitation is detectable as a rattling noise and results in low

pump efficiency and high risk of damage to the pump.

• To prevent cavitation the NPSH available from the system

must be greater than NPSH required by the pump.


Pump Efficiency

Reservoir

Source

Motor (4)

Real

work

Done

Pipe

losses

Pump

losses

Motor

losses


Delivered power

• Delivered power is the power delivered by the pump to the liquid. The value of this power depends upon three factors:

• Flow

• Head

• Specific Gravity of the liquid – i.e. a pump which delivers petrol does less work than when it delivers sulphuric acid, because the specific weights of the two liquids are different.

• The power which the pump consumes is the absorbed power.


Absorbed or Shaft power

This is the power that the pump absorbs from the motor.

The absorbed power includes:

• Delivered power to the liquid

• Hydraulic losses within the pump

• Friction losses within the pump


Efficiency

• Pump efficiency is obtained by comparing the power delivered

to the liquid to the power absorbed by the pump.

• For example a pump that is 75% efficient only delivers 75% of

the absorbed power, the remaining 25% is lost within the pump.

• The efficiency of a motor is obtained by dividing its nameplate

power output by the input power consumed from the ESB

sometimes referred to as P1 and P2. The efficiency losses are

made up of heat and iron losses within the motor.

• The overall pump/motor efficiency is calculated by multiplying

both.


• Water kW = ρ . g . Q . H

• = ρ . Q(m3/hr) x H(m)

367

• Pump input power

= Q(m3/hr) x H(m)

367 x η

Power - Efficiency

2 - tea water services - pump training final mf

Documents