Moteur à chaleur pour piscine : comparaison – au meilleur prix – meilleur avis – Pompe à filtre pour piscine : pas cher – guide achat – soldes – Moteur pour piscine : moins cher – black friday – pas cher – The Basics of Pool Pumps – Article

PRIMED FOR ACTION


A pump powered by an electric
motor, is the essential piece of mechanical equipment that creates the hydraulic flow and
pressure needed to circulate water through a pool or spa’s plumbing system and
related equipment. The pump is nothing less than the literal heart of the pool/spa system
to which it is linked. Without exception, pools and spas have pumps. Other equipment,
including filters, heaters and automatic sanitizers, will work only when the pump moves
water through the system. To assist working with these devices, we have assembled the
following list of terms and definitions. Please note, All deftnitions are provided as they
relate to pool and spa systems; they maybe defined differently in other industry or
science manuals.

GENERAL TERMS

Cavitation: The vacuum created when the discharge capacity of the pump
exceeds water replacement in the suction line. Cavitation occurs when the pump is
oversized, when the diameter of the influent line is too small or when there is an
excessiveiy long influent line. Cavitation causes bubbling and vibrations that can damage
the pump if they occur over an extended period.

Centrifugal force:
The outward force created by anything in circular motion. In centrifugal pumps, this is
the force created when water is propelled outward by the circular motion of the impeller.

Centrifugal pump:
The only type of pump used in a pool or spa circulation system. Uses centrifugal force
created by the rotation of the impeller to power water through the circulation system.

Circulation system
(recirculation system): Powered by the pump, this is the system of pipes and equipment
through which pool and spa water circulates. Water cycles from the main drain and skimmer
drain via the influent plumbing line, through the pump, filter, heater and automatic
sanitation equipment, and back to the pool or spa through the effluent plumbing line via
the return inlets.

Diffuser: A
housing or varied part that fits around the impeller. The diffuser strips water from the
rotating impeller and forces it out the discharge line of the pump, reducing the velocity
of water through the pump while increasing the static pressure. In some pump models, the
diffuser and the volute are designed as a single part.

Effluent line:
The plumbing line leading from the equipment to the pool or spa.

Electric motor:
The power source of a centrifugal pump that converts electrical energy into mechanical
energy.

Flow meter: A
gauge installed in the circulation line that measures the flow rate in gallons per minute
(gpm).

Flow rate:
The volume of water flowing past a given point during a specified time; measured in
gallons per minute (gpm) or gallons per hour (gph).

Head: A
measure of the amount of pressure or resistance in a hydraulic system. Resistance may
include the vertical distance and the amount of friction in a system and is measured in
pounds per square inch (psi) or inches of mercury.

Impeller: A
circular pump part with vanes that rotates to provide centrifugal force for propelling
water in the circulation system. The impeller spins on the end of the electric motor shaft
and is the only moving part of a centrifugal pump. Closed, semi-open or open impellers are
used:

Closed impeller:
A pump impeller with vanes contained on both sides and an opening in    the
center (the eye) Water enters the eye and is centrifugally forced out the end of the
closed impeller.

Semi-open impeller:
A pump impeller with vanes exposed on one side; open vanes face    the volute
wall, forming chambers through which the water flows.

Open impeller:
A pump impeller with exposed vanes like a water wheel. (Open impellers    
are rarely used in pumps manufactured for use in the pool and spa industry.)

Influent line:
The plumbing line that leads from the pool or spa to the equipment. Also known as the
suction line.

Pressure differential:
The difference in water pressure between two points in a hydraulic system.

Pressure gauge:
A gauge that measures the amount of pressure built up inside a closed system.

Prime
(priming the pump): Initiating or restarting the water flow in a circulating system,
usually accomplished by filling the pump volute by hand, turning the pump on and allowing
the pump to disperse all air from the influent line.

Pump capacity:
The volume ot water a pump can circulate through a given resistance (total dynamic head)
during a period of time; expressed as gallons per minute (gpm) or gallons per hour (gph).

Pump curve:
The curve on a bar graph that shows the performance characteristics of pumps. Variables
include size, flow rate and resistance factors.

Self-priming
centrifugal pump: A centrifugal pump that automatically removes air from the
suction line and replenishes itself with water from within the pump, permitting
uninterrupted water flow. In comparison, a flooded suction centrifugal pump would require
manual priming if air interrupted the flow of water through the pump.

Strainer basket:
A plastic mesh basket positioned in the strainer pot that traps debris in the water before
it reaches the impeller.

Strainer pot:
A housing on the influent side of the pump that serves as a priming chamber and a
receptacle for the strainer basket.

Total dynamic head:
The sum of all the resistance in a pool amd spa circulation system during operation.

Turnover rate:
The time required to circulate a volume of a given pool or spa.

Two-speed centrifugal
pump: A centrifugal pump that has a two-speed motor that turns the shaft and
impeller at two revolutions-per-minute (rpm) levels, providing an optional pump Capacity.

Velocity: The
speed of water as it flows between two points; expressed in feet per second.

Velocity head:
The amount of energy required to accelerate water to a given velocity; expressed in feet
of head.

Volute: A
housing that contains the impeller and diffuser. (The diffuser is sometimes designed
within the volute, instead of being a separate part.) Water is propelled through the
volute’s continuously enlarging spiral chamber, increasing the effect of the
centrifugal force initiated by the spinning impeller.

Pumps by the numbers


Behold the pump: It seems such
a simple little piece of pool equipment, but its looks certainly are deceiving. In fact,
the pump is unquestionably the most important single piece of equipment in the circulation
system, no matter the size or type of pool. Looks are similarly misleading when it comes
to selecting the right pump for the job: A surprisingly long list of factors must be taken
into account in order to choose the pump best suited to a given pool side task.
‘Right size’ is not an absolute but rather depends on a number of variables that
will change from pool to pool. In that light, pump selection becomes an act of balancing
pool size and the pool’s hydraulic system against customer satisfaction, including a
pump’s economic efficiency and quiet performance.

DOWN TO BUSINESS


To select the best pump for the job, you will need to determine the pool volume and
the number of gallons it will hold; the required flow rate with respect to turnover time;
and the system’s total dynamic head (the friction loss due to piping, fittings and
equipment).


Once these variables are determined by simple mathematics, you will be ready to
select the pump that has all the right stuff for any type of pool. Moreover, even if you
are replacing a pump in an existing system, it’s best to go through these simple
calculations to make sure you’re installing the right pump for the job.

Pool volume:



To calculate volume, you’ll need to use some basic geometry to estimate the number
of cubic feet in the pool. Don’t worry about the math— the equations are simple,
and all you need to do is plug in the numbers and multiply. First, you need the basic
dimensions of the pool; if you don’t have the specs handy you’ll need to measure
it. Don’t be too concerned about absolute accuracy because close estimates will be
adequate for these equations. (Although if you must estimate, be sure not to
underestimate.) For simplicity, make your measurements in feet and tenths of feet to keep
your calculations in easy decimal form.

Naturally, the shape of the
pool will determine which equation to use to calculate the volume in total cubic feet. To
find the number of cubic feet in a square or rectangular pool, multiply the length by the
width, then multiply by the average depth. This tells you the number of cubic feet in the
pool. To calculate the volume of an oval swimming pool, multiply the length by the width,
then multiply by the constant, pi (3.14).That number in turn is multiplied by the average
depth of the pool.

If the pool is circular, you
can calculate the number of cubic feet by multiplying the radius (one-half the diameter)
of the pool by itself (that is, the radius squared) and multiplying that by pi (3.14).
Again, you multiply the total by the average depth to find the volume.

When working on an
irregular-shaped or free-form pool, estimate the volume by using the equation for an oval
or rectangle as needed. If you really want to get technical, you can measure the pool with
a planimeter, but that is not necessary here: All you need is a close estimate.

Pool capacity:
Once you’ve calculated the volume of the pool in cubic feet, you will want to
calculate the number of gallons of water that the pool will hold, There are 7.5 gallons in
1 cubic foot of water, so simply multiply the number of cubic feet in the pool by 7,5.

Flow rate:
Now that your calculator is warmed up, it’s time to determine the flow rate needed to
circulate the number of gallons of water contained in the pool by the preferred turnover
time, The recommended turnover time varies between regions of the country and individual
preferences, but eight hours can Be considered an adequate turnover time. Simply divide
the number of gallons of water in the pool by the turnover time, eight hours, to find the
flow rate in gallons per hour, Then convert this figure into gallons per minute, by
dividing by 60.

Total dynamic head:
Total dynamic head (TDH) is the sum of the resistance experienced by water flowing through
the circulation system. Resistance is applied throughout the system — when water
Flows through elbows, fittings, valves, equipment and even through straight lengths of
pipe. The TDH will affect flow rate and therefore is an important factor in selecting the
right pump. All components in the circulation system, from the skimmer and main drain to
the return inlets, must be factored into TDH calculations. Referring to the circulation
system blueprints, list all components and dimensions, including the total length and size
of PVC pipe and copper pipe, the skimmer and drains, 45 degree elbows, 90 degree elbows,
gate valves, backwash valves, and the size and type of filter and heater.

The next step calls for
consulting head-loss charts provided by pump manufactures to find the appropriate value
for each component. Most manufactures have developed their own methods for interpreting a
pool’s needs, so contact them to obtain charts that detail their preferred
techniques. Once your list of values is complete, add them together; their sum is the
total dynamic head.

CHOOSING THE RIGHT
PUMP


After making these calculations, the rest is simple: Just choose a pump model that
provides the flow rate you need, taking into consideration the head loss in the system. As
an aid, pump manufactures have developed pump curves that show the performance
characteristics for pumps on the market. These curves are plotted on a grid to indicate
the size of pump needed to produce the calculated flow rate with respect to the loss of a
system. To use the curve, just locate the required flow rate and head along the borders of
the chart and extend lines to a point where the two values intersect. The proximity of the
point with the pump curves plotted on the graph will indicate which pump you should
choose. If your specs fall between the curves of two pump models, choose the larger model
rather than the smaller one.

While you will need a pump big
enough to do the job, be careful not to exceed the maximum flow rate recommended for the
plumbing, filter and heater. If water is pumped through the system at too high a velocity,
it may damage the equipment, cause cavitation that may damage the pump, or strip the metal
from copper pipes to produce copper stains on pool walls. Pool piping must be of the
correct size to handle the needed flow rate without causing the water to flow too fast.
Water velocity should not exceed 10 feet per second for discharge piping or 8 feet per
second for suction piping when PVC piping is used. In the case of copper piping, the
velocity should in no case exceed 8 feet per second, according to the National Spa &
Pool Institute Residential Pool Standard. Now you’ve narrowed the selection process
down to choosing your preferred brand of pump. You’re probably already familiar with
most of the pumps on the market from the pools you service on your route, so the decision
won’t be all that tough.

TO A PUMPS GOOD HEALTH


A self-priming centrifugal pump provides the power to circulate water from the pool
through the influent (vacuum) line; into and through the filter, heater and automatic
sanitation equipment; and back to the pool through the effluent (discharge) line. That may
sound simple, but there’s a lot more to it than that.first of all, the pump is
powered by an attached electric motor, which converts electrical energy into mechanical
energy that spins the motor shaft. As the shaft spins, the pump impeller fitted on the end
of the shaft spins at high speeds.As water is propelled (pushed) by the pump through the
effluent line, water is displaced (pulled) by atmospheric pressure from the influent side
of the pump through the eye of the impeller and against the impeller blades. The spinning
impeller then propels the water outward in a circular motion that creates centrifugal
force. As though that weren’t enough, the action of the impeller on the water creates
energy in the form of water velocity. Simply stated, the faster the impeller spins, the
greater the velocity of the water flow.

The velocity of the water is
converted to pressure when it passes through the volute, a continuously enlarging spiral
chamber, before exiting the pump through the effluent line. (in some pump models the
diffuser and volute are designed as a single part.) Parts of this system break down from
time to time. The text that Follows offers a guide to getting the pump up and running
again.

PUMP TROUBLESHOOTING


To repair a disabled pump, you’ll need to know the workings of a centrifugal
pump inside and out, Are you prepared? First, you’ll need to know a bit about motors
and their potential problems and Learn to troubleshoot them. For more information, consult
P/SN’s Nov. 28, 1988, issue, pp. 82-83; or P/SN’s special publication, The
Basics of Motor Maintenance.From that point on, the information below will serve as your
guide. But please remember: Before working on a pump or motor, be sure to disconnect the
electric power at the fuse or breaker box. In addition, place a sign on the fuse/breaker
box to alert others that the electricity is turned off specifically for equipment repair,
to ensure that the electricity is not turned on by another person. You’ve looked over your
swimming pool equipment and diagnosed the problem as a leaking pump.

What to do?
  Before you take our your toolkit, spend some time with this refresher course on
basic pump teardown and repair. Murray Hunt, who for two decades has been repairing and
reviving ailing pumps in Southern California, provides step-by-step guidance in working on
a bit of equipment familiar to most technicians: the Purex Series AH bronze pump,
manufactured by Hydrotech Chemical Corp., Marietta Ga. Once you have assembled the proper
tools, Hunt says, the procedure for curing what ails the pump is pretty straightforward
provided you exercise due care in handling pump parts and take some necessary precautions
before working on the motor. First, shut off the electricity at the fuse box, suggests
Hunt. If that’s not possible, turn off the power at the timer. At all locations,
leave a note that the power is off to permit completion of repairs. « You absolutely
don’t want anyone to turn the current back on while you are working, » Hunt says.
Also, double check the motor’s electrical connections with a voltage meter or
multimeter to ensure that the electricity is indeed off.

Once you remove the
motor’s terminal cover and disengage the electrical wires and conduit from the motor
housing, you’re ready to tackle the task at hand. A final caution: pump brass is a
durable, but soft material, Unless you are absolutely confident you have the
jeweler’s touch needed to do the job as gently as is necessary, you would be well
advised to use a mallet or soft hammer to avoid bending the seal flange or impeller.