Centrifugal Pumps - blog

Adjustable Speed Drives As Applied To Centrifugal Pumps -2

Figure 6. Combined Curves

Figure 7 shows a typical Centrifugal Pump and efficiency curve for operation
at a fixed speed. It can be seen that for fixed speed operation,
the efficiency varies as flow is adjusted. For adjustable speed
operation however, the affinity laws predict that the Centrifugal Pump  curve
will shift downwards for reduced speed and the efficiency curve
will shift to the left in such a way that efficiency will remain constant
relative to points on the Centrifugal Pump  curve for reduced flows.

Figure 7. Fixed Speed Pump Efficiency

FLOW CONTROL TECHNIQUES
Historically, fixed speed AC motors have driven centrifugal pumps
and reduced flow has been achieved by using control valves as
shown in figure 8. Closing the valve reduces the flow by increasing
the friction in the system. The modified system curve and the
new operating point can be represented as shown in figure 9.
Note that the desired reduction in flow has been achieved, but at
the expense of increased system pressure relative to 100% flow.

An alternative approach to valve control is shown in figure 10.
Reducing the Centrifugal Pump  speed causes the Centrifugal Pump  curve to shift downwards
as shown in figure 11. Since the operating point is still
determined by the intersection of the reduced speed Centrifugal Pump  curve
and the system curve, it is possible to achieve the same reduced
flow as achieved with a valve, but at significantly less pressure.

Figure 9. Throttle System

In addition to energy savings, which are discussed in detail later,
operation at reduced pressures can result in longer Centrifugal Pump  seal
life, reduced impeller wear, and less system vibration and noise.
These benefits could provide additional savings over potential
energy savings.

Figure 10. Adjustable Speed Control
ENERGY SAVINGS
The Centrifugal Pump  output power, or hydraulic power, can be expressed as:
Horsepower = Head (Feet) x Flow (GPM) x Specific Gravity
3960
Therefore, for any given liquid, the power that the Centrifugal Pump  must
transmit is proportional to the head times the flow and can be
represented by rectangles for each operating point as shown in
figure 11.

Tags: Centrifugal Pumps

Posted in Centrifugal Pumps, Hydraulic Pumps, Surface Pump | No Comments »

Adjustable Speed Drives As Applied To Centrifugal Pumps -1

These characteristics are important when one considers a typical
duty cycle for a Centrifugal Pump application. A typical operating cycle
might be represented by the bar chart shown in figure 3.
Centrifugal pumps are generally sized to handle the peak flow
requirements, which typically occur for very short periods of time.
Consequently, the equipment would be operated at reduced flows
most of the time. For this example, the system would be operated
below 70% flow over 94% of the time. Thus, this sort of duty
cycle could provide energy savings by adjustable speed operation
of the Centrifugal Pump .

PUMP BASICS
An understanding of the basic operating characteristics of centrifugal
pumps is necessary to apply these concepts to any particular
application.
Figure 4 shows a Centrifugal Pump  curve describing the head (or pressure)
versus flow characteristics of a typical Centrifugal Pump . This
curve shows that the pump will produce limited flow if applied to
a piping system in which a large pressure differential is required
across the Centrifugal Pump to lift the liquid and overcome resistance to flow
(as at point A). Higher flow rates can be achieved as the required
pressure differential is reduced (as at point B).
To determine where along this curve the Centrifugal Pump  will operate in a
given application requires the additional information provided by
the system curve. This curve, shown in figure 5, represents the
characteristics of the piping system to which the Centrifugal Pump is applied.
The head required at zero flow is called the static head or lift.

This shows how many feet of elevation that the Centrifugal Pump  must lift
the fluid regardless of the flow rate. Another way to describe static
head is to think of it as the amount of work needed to overcome
the effects of gravity.

Figure 5. System Curve
The other component of head is called the friction head and
increases with increasing flow. Friction head is a measure of the
resistance to flow (backpressure) provided by the pipe and its
associated valves, elbows, and other system elements.
The intersection of the Centrifugal Pump  and system curves shows the natural
operating point for the system without flow control, as shown
in figure 6. This intersection would generally be chosen to ensure
that the pump is operated at or near its best efficiency point.

Tags: Centrifugal Pumps

Posted in Centrifugal Pumps | No Comments »

Adjustable Speed Drives As Applied To Centrifugal Pumps

Foreword
This article is a revised edition of the original D-7108 application
note as written by Dennis P. Connors, John D. Robechek, and
Dennis A. Jarc. Centrifugal Pumps The overall content and principles of this 1982
publication are still very much valid and relevant today. The significant
changes that have occurred since this article was originally
published is in AC technology. The dominant method of AC control
is by PWM inverters, particularly with the advent of the high
speed Insulated Gate Bipolar Transistors (IGBTs). This will be the
only drives technology to be considered in this revisited analysis.

ABSTRACT
Centrifugal Pumps are generally sized to operate at or near the
best efficiency point at maximum flow. The maximum flow
requirements, however, frequently occur for a very short period
during the operating cycle with the result that some method of
flow control is required. Centrifugal Pumps ,The traditional approach to flow control
has used valves; which increase system pressure, inherently

Figure 1. Affinity Laws for Centrifugal Pumps

waste energy, and generally cause the pump to operate at
reduced efficiencies.
Adjustable speed drives (ASDs) can achieve reduced flow by providing
adjustable speed pump operation. This results in reduced
system pressure and operation near the pump’s Best Efficiency
Point (BEP). Centrifugal Pumps In addition, maintenance costs might be reduced.
This paper will discuss the energy savings potential of AC ASDs
followed by a brief description of the operation and relative benefits
of PWM AC drives.
CENTRIFUGAL PUMP APPLICATIONS AND ENERGY
SAVINGS POTENTIAL
Centrifugal Pumps  are used on many industrial and commercial
applications. Many of these pumps are operated at fixed speeds,
but could provide energy savings through adjustable speed operation.
Reviewing the affinity laws for Centrifugal Pumps and a typical
operating cycle for a centrifugal application will show this.
Figure 1 graphically illustrates the physical laws of centrifugal
pumping applications. The flow is directly proportional to speed;
pressure is proportional to the square of the speed; and power is
proportional to the cube of the speed. These relationships can
also be expressed numerically as shown in figure 2. Theoretically,
it would be possible to operate at 50% flow with only 13% of the
power required at 100% flow. Since the power requirements
decrease much faster than the reduction in flow, the potential
exists for significant energy reduction at reduced flows.

Tags: Centrifugal Pumps

Posted in Centrifugal Pumps | No Comments »

CHF CENTRIFUGAL PUMP(MEDIUM FLOW)

CHF CENTRIFUGAL PUMP(MEDIUM FLOW)

centrifugal pump

Tags: Centrifugal Pumps

Posted in Hydraulic Pumps | No Comments »

Centrifugal Pumps Description of Features

Centrifugal Pumps Electronic Motor Overload Protection
The SMC-3 controller incorporates, as standard, electronic motor
overload protection. This motor overload protection is accomplished
electronically with the use of current transformers on each of the
three phases. Centrifugal Pumps The controller’s overload protection is programmable,
providing the user with flexibility. The overload trip class selection
consists of either OFF, 10, 15, or 20. The trip current is easily
selected by adjusting the rotary potentiometer to the motor full load
current rating. Trip reset is selectable to either automatic or manual
mode.
Centrifugal Pumps Note: Trip rating is 120% of dial setting.
Over-temperature
The SMC-3 monitors the SCR temperature by means of internal
thermistors. When the power poles maximum rated temperature is
reached, the microcomputer switches off the SMC, a TEMP fault is
indicated via LED, and the 97/98 fault contact closes.
Phase Reversal Protection
When enabled via a DIP switch, 3-phase input power will be verified
before starting.Centrifugal Pumps If input power phasing is detected to be incorrect,
the start will be aborted and a fault indicated.

Phase Loss/Open Load
The unit will not attempt a start if there is a single-phase condition
on the line. Centrifugal Pumps This protects from motor burnout during single-phase
starting.

Centrifugal Pumps Phase Imbalance
The unit monitors for imbalance between phase currents. To prevent
motor damage, the unit will trip if the difference between the
minimum phase current and the maximum phase current exceeds
65% for 3 seconds, and a fault will be indicated.
Shorted SCR
Prior to every start and during starting, the unit will check all SCRs
for shorts and unit load connections to the motor.Centrifugal Pumps  If there is a
shorted SCR in the SMC-3 and/or open load, the start will be
aborted and a shorted SCR or open load fault will be indicated. This
prevents damage from phase imbalance.

Centrifugal Pumps Push to Test
The unit with control wiring can be tested for fault conditions by
using the Push to Test function. Hold down the Reset button for 7
seconds to activate the fault Aux (97, 98) and shut down the SMC-3.
To clear,Centrifugal Pumps  either push the Reset button or cycle control power to the
device.
Centrifugal Pumps Modes of Operation/Features
LED Description (Number of Flashes)
1. Overload
2. Overtemperature
3. Phase Reversal
4. Phase Loss/Open Load
5. Phase Imbalance
6. Shorted SCR
7. Test

Tags: Centrifugal Pumps

Posted in Centrifugal Pumps | No Comments »

Centrifugal Pumps Description of Features

Centrifugal Pump Electronic Motor Overload Protection
The SMC Flex controller incorporates, as standard, electronic motor
overload protection. This overload protection is accomplished
electronically with an I2t algorithm.
When coordinated with the proper short circuit protection, overload
protection is intended to protect the motor, motor controller, Centrifugal Pump and
power wiring against overheating caused by excessive overcurrent.
The SMC Flex controller meets applicable requirements as a motor
overload protective device.Centrifugal Pump
The controller’s overload protection is programmable, providing the
user with flexibility. The overload trip class consists of either OFF,
10, 15, 20 or 30 protection. Centrifugal Pump The trip current is programmed by
entering the motor full-load current rating, service factor, and
selecting the trip class.
Thermal memory is included to accurately model motor operating
temperature. Ambient temperature insensitivity is inherent in the
electronic design of the overload.
Stall Protection and Jam Detection
Motors can experience locked-rotor currents and develop high
torque levels in the event of a stall or a jam. Centrifugal Pump These conditions can
result in winding insulation breakdown or mechanical damage to the
connected load. Centrifugal Pump The SMC Flex controller provides both stall
protection and jam detection for enhanced motor and system
protection. Stall protection allows the user to program a maximum
stall protection delay time from 0…10 seconds. The stall protection
delay time is in addition to the programmed start time and begins
only after the start time has timed out. If the controller senses that
the motor is stalled, Centrifugal Pump it will shut down after the delay period has
expired. Jam detection allows the user to determine the motor jam
detection level as a percentage of the motor’s full-load current
rating. To prevent nuisance tripping, a jam detection delay time,
from 0.0…99.0 seconds, can be programmed. This allows the user
to select the time delay required before the SMC Flex controller will
trip on a motor jam condition. The motor current must remain above
the jam detection level during the delay time. Jam detection is
active only after the motor has reached full speed.
Centrifugal Pump Underload Protection
Utilizing the underload protection of the SMC Flex controller, motor
operation can be halted if a drop in current is sensed.
The SMC Flex controller provides an adjustable underload trip
setting from 0…99% of the programmed motor full-load current
rating with an adjustable trip delay time of 0…99 seconds.
Undervoltage Protection
The SMC Flex controller’s undervoltage protection will halt motor
operation if a drop in the incoming line voltage is detected.Centrifugal Pump,
The undervoltage trip level is adjustable as a percentage of the
programmed line voltage, from 0…99%. To eliminate nuisance trips,
a programmable undervoltage trip delay time of 0…99 seconds can
also be programmed. The line voltage must remain below the
undervoltage trip level during the programmed delay time.
Centrifugal Pump Overvoltage Protection
If a rise in the incoming line voltage is detected, the SMC Flex
controller’s overvoltage protection will halt motor operation.
The overvoltage trip level is adjustable as a percentage of the
programmed line voltage, from 0…199%. To eliminate nuisance
trips, a programmable overvoltage trip delay time of 0…99 seconds
can also be programmed.Centrifugal Pump The line voltage must remain above the
overvoltage trip level during the programmed delay time.
Centrifugal Pump Voltage Unbalance Protection
Voltage unbalance is detected by monitoring the 3-phase supply
voltage magnitudes in conjunction with the rotational relationship of
the three phases. The controller will halt motor operation when the
calculated voltage unbalance reaches the user-programmed trip
level.
The voltage unbalance trip level is programmable from 0…25%
unbalance.

Centrifugal Pump Excessive Starts Per Hour
The SMC Flex controller allows the user to program the allowed
number of starts per hour (up to 99). This helps eliminate motor
stress caused by repeated starting during a short time period.

Metering
Centrifugal Pump Power monitoring parameters include:

Tags: Centrifugal Pumps

Posted in Centrifugal Pumps | No Comments »

Centrifugal Pumps Optional Modes of Operation

Centrifugal Pump Control - Start and Stop
This option is used to reduce surges during the starting and stopping of a Centrifugal Pump  by smoothly accelerating and decelerating the motor. The microprocessor analyzes the motor variables and generates commands which control the motor and reduce the possibility of surges occurring in the system. The Centrifugal Pump control module also provides a built-in anti-backspin timer.

Centrifugal Pump  Braking Control
SMB Smart Motor Braking
This option provides motor braking for applications that require the motor to stop faster than a coast to rest. Braking control, with automatic zero speed shut off, Centrifugal Pump is fully integrated into the compact design of the SMC controller. This design facilitates a clean, straight forward installation and eliminates the requirement for additional hardware such as braking contactors, resistors, timers, and speed
sensors. Centrifugal Pump The microprocessor based braking system applies braking current to a standard squirrel-cage induction motor. The strength of the braking current is programmable from 150…400% of full-load current.

Accu-Stop
Centrifugal Pump This option is used in applications requiring controlled position stopping. During stopping, braking torque is applied to the motor until it reaches preset slow speed (7% or 15% of rated speed) and holds the motor at this speed until a stop command is given.Centrifugal Pump  Braking torque is then applied until the motor reaches zero speed.
Braking current is programmable from 0…400% of full-load current. Slow Speed Current is programmable from 0…450% of full-load current. Slow speed can be programmed for either 7% (low) or 15% (high).

Slow Speed with Braking
Centrifugal Pump Slow Speed with Braking is used on applications that require slow speed (in the forward direction) for positioning or alignment and also require braking control to stop. Slow speed adjustments are 7% (low) or 15% (high) of rated speed.Centrifugal Pump  Slow speed acceleration current is adjustable from 0…450%. Slow speed running current is adjustable from 0…450% of full-load current. Braking current is
adjustable from 0…400%.

Tags: Centrifugal Pumps

Posted in Centrifugal Pumps | No Comments »

Centrifugal Pumps Modes of Operation

Centrifugal Pumps ,The SMC Flex controller provides the following modes of operation as Standard:

Soft Start
This method covers the most general applications. The motor is
given an initial torque setting, which is user adjustable. From the
initial torque level, the output voltage to the motor is steplessly
increased during the acceleration ramp time, which is user
adjustable.
Centrifugal Pumps Selectable Kickstart
The kickstart feature provides a boost at startup to break away
loads that may require a pulse of high torque to get started. It is
intended to provide a current pulse, for a selected period of time.
Current Limit Start
Centrifugal Pumps ,This method provides current limit start and is used when it is
necessary to limit the maximum starting current. The starting current
is user adjustable. The current limit stating time is user adjustable.
Dual Ramp Start
This starting method is useful on applications with varying loads,
starting torque, and start time requirements.Centrifugal Pumps , Dual Ramp Start offers
the user the ability to select between two separate start profiles with
separately adjustable ramp times and initial torque settings.

Centrifugal Pumps Full Voltage Start
This method is used in applications requiring across-the-line
starting. The SMC controller performs like a solid-state contactor.
Full inrush current and locked-rotor torque are realized. The SMC
may be programmed to provide full voltage start in which the output
voltage to the motor reaches full voltage in 1/4 second.
Linear Speed Acceleration
With this type of acceleration mode, a closed-loop feedback system
maintains the motor acceleration at a constant rate. The required
feedback signal is provided by a DC tachometer coupled to the
motor (tachometer supplied by user 0…5V DC, 4.5V DC = 100%
speed). Kickstart is available with this mode.
Preset Slow Speed
Centrifugal Pumps ,This method can be used on applications that require a slow speed
for positioning material. The Preset Slow Speed can be set for either
Low, 7% of base speed, or High, 15% of base speed. Reversing is
also possible through programming. Speeds provided during
reverse operation are Low, 10% of base speed, or High, 20% of
base speed.
Soft Stop

Tags: Centrifugal Pumps

Posted in Centrifugal Pumps | 1 Comment »

CGA CENTRIFUGAL PUMP(WITH OPEN IMPELLERS)

Centrifugal Pumps Operating Limits:
-Max.suction head:8m
-Max.liquid temperature:60°C
-Max.environment temperature:40°C
-Continuous duty

Centrifugal Pumps Motor:
-Two-Pole induction motor(n=2900r.p.m.)
-Insulation Class B/F
-Protection IP44

Centrifugal Pumps Material:
-Pump body: Cast Iron
-Impeller: Brass
-Motor Shaft: Hi-Cr plated 45# Steel/2Cr13# Stainless Steel/S.S#304 Welding shaft
-Mechanical seal: Ceramic/Graphite

Centrifugal Pumps Application:
·Centrifugal Pumps  single impeller low head water pumps for flow irrigation systems with flow rates.
·Suitable to pump clean water or nonaggressive liquids charged with small solid impurities.
·To be used in flow irrigation systems in gardening and agriculture and industrial fittings.Centrifugal Pumps

Tags: Centrifugal Pumps

Posted in Centrifugal Pumps | No Comments »

Fluid Mechanics Laboratory Centrifugal Pump Investigation(6)

V. Centrifugal Pump Report
A formal written report is not required for this experiment. You are responsible for the plots, table,
and the discussion questions listed below. Your responses to the discussion questions are to be typed
with 1-1/2 to double spacing, using a character font no smaller than 12 point on 8 ½ by 11 inch paper.
The margins should be at least 1 inch on all sides. As this represents the discussion and results of a full
lab report, the length of the discussion question responses should be no longer than 2 pages. Grammar,
spelling and sentence structure will also be taken into account as part of the formatting section of grading.
Also include a reference section if necessary.Centrifugal Pump
Plots, tables and other figures, should be prepared using appropriate software such as Excel,
KaleidaGraph, TecPlot, or equivalent. For the plots, keep all axis limits and divisions the same so that
you can easily compare results in different plots. Be sure to connect the data points with lines or trend
lines, and use symbols that allow easy discernment of the different data sets. Read the Laboratory
Technical Report Requirements handout and follow the guidelines included for all aspects of plot and
table preparation.

Centrifugal Pump Data Reduction
You will need to calculate the total head, brake power, water power and efficiency for the plots
and table. Remember to check units and the “T” in brake power equation (equation 4) is torque in Nm not
temperature.
Plots and Tables
You will prepare a total of 12 plots and 1 table of the results as follows:
1. Centrifugal Pump For each speed, overlay the data for both normal and reverse impeller installations on the same
plot:
a. Flow rate Q vs. head H, and pump efficiency η. Put head on the left y-axis and efficiency
on the right y-axis. (4 plots, reflecting the 4 speeds tested.)
b. Flow rate Q vs. water power Pw, brake power Pb, and pump efficiency η. Put Pw and Pb
on the left y-axis and efficiency on the right y-axis. (4 plots, reflecting the 4 speeds
tested.)
2. For each impeller orientation overlay all 4 speeds on the same plot:
a. Flow rate Q vs. head H, and Centrifugal Pump efficiency η. As before, put head on the left y-axis
and efficiency on the right y-axis. (2 plots, reflecting the 2 impellers tested.)

b. Flow rate Q vs. horsepower Pw, brake power Pb, and Centrifugal Pump efficiency η. As before, put
Pw and Pb on the left y-axis and efficiency on the right y-axis. (2 plots, reflecting the 2
impellers tested.)
3. Prepare a data table showing the following for each impeller and speed tested (8 cases):
maximum head; maximum flow rate; head at maximum flow rate; optimum efficiency; brake
power, flow rate and head at maximum efficiency.
VI. References
1. Fluid Mechanics, 4th Edition, Frank M. White, WCB McGraw-Hill, 1999.
2. Introduction to Fluid Mechanics, 4th Edition, Robert W. Fox and Alan T. McDonald, John Wiley & Sons, Inc.,
1992.
3. Instruction Manual: Centrifugal Pump Demonstration Unit, Armfield, Inc.
4. The Hydraulic Institute, http://www.cacheng.com

Tags: Centrifugal Pumps

Posted in Centrifugal Pumps, Hydraulic Pumps | No Comments »