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| We
offer a complete line of swimming pool pumps and parts, from
all the major manufactures. Sta-rite, Hayward,
American Products, Purex, Pac Fab, Jacuzzi and others Whether
its a single part or a complete pump we can supply your needs. |
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| For information on: COMPLETE
PUMPS |
| For information on: PUMP
PARTS |
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The
Swimming Pool pump is probably the most important single
piece of equipment in the circulation system.
Selecting
a pool pump is determined by a long list of factors. It
is best to review this list even if you are replacing an
existent pump with the same size. If you are tempted to
increase the HP of the pump, you must read and understand
this.
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Calculate
the pool's capacity. Calculating the pool's capacity is a
question of calculating the pool volume. The basic calculation
for a rectangular pool is length x width x average depth.
This will give the cubic feet of water. To Calculate the volume
of an oval pool multiply the length x width x 3.14 x average
depth. To calculate the volume of a round pool. multiply the
radius x radius x 3.14. In taking measurements it is
best to over-estimate. |
Pool's water volume is
calculated by taking the volume (cubic feet) and multiplying
it by 7.5 gallons per cubic feet.
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Calculate the required flow rate.
This is done by taking the total gallons and dividing the
total gallons by 8 hours(turnover), to give the flow per hour
and then divide again by 60, to give the flow per minute.
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Total dynamic head (TDH) is the sum of the
resistance experienced by water flowing through the pipes
and filter system. Each elbow, foot of pipe, fittings and
anything else that is in the circulation system increases
the Total Dynamic Head. The TDH will affect the flow rate.
For a new pool this is somewhat more easy to calculate, but
for an existing pool, with piping below the ground is. |
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Typical Calculation:
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1. Friction Loss (vacuum Side)
Common Head loss factors - Vacuum (at
pump) - Assumes 2" suction pipe not to exceed 40 feet,
minimal fittings - one 2" valve and full rated pump.
| Horsepower
of Pump |
Feet
of water |
|
3/4
|
4.5
- 5.5 ft of water |
|
1
|
7.0
- 9.0 ft of water |
|
1-1/2
|
10.0
- 12.5 ft of water |
|
2
|
13.5
- 16 ft of water |
Let's
use a 1 HP pump to perform a calculation, Reading the table
above we have 9 feet of head.
2.
Friction loss (pressure side).
_____(clean filter pressure)
psig. x 2.31 ft of head / psig. = _________ft of head (pressure
side).
Typically filter pressure
should be 10-15 lbs.
Using
10 feet of pressure with have 23 ft of head on the pressure
side.
3.
The Total Dynamic Head:
_____9______
+ ____23____ = ____32_______
Resistance Vacuum
Resistance pressure
total resistance to flow
feet of water
feet of head
feet of head
Practically
speaking 30-40 feet of head is a good estimate to size a
pump. which can be adjusted upward or downward depending
on the circumstances.
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Pipe characteristic (maximum Flow)
|
| Pipe
Size (PVC) |
Suction
Line (vacuum) |
Return
Line (pressure) |
| 1-1/2
" |
50
GPM |
65
GPM |
| 2 |
85
GPM |
105
GPM |
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A typical performance chart
|
| Pump
Size |
Pump
Output (GPM) versus Total Resistance to Flow (feet of
Head) |
| |
20
ft |
30
ft |
40
ft |
50
ft |
60
ft |
70
ft |
| 1/2 |
55 |
45 |
29 |
|
|
|
| 3/4 |
67 |
58 |
47 |
31 |
|
|
| 1 |
85 |
76 |
65 |
50 |
27 |
|
| 1-1/2 |
97 |
90 |
80 |
67 |
50 |
10 |
| 2 |
116 |
111 |
99 |
85 |
70 |
51 |
NOTES: Numbers in table represent typical
information, consult specific information for the pump you
intend to use.
Move up to next level of resistance 32 -> 40 feet and
specify the pump that exceeds the calculated flow rate.
(47 versus 35 gpm).
Select
a filter based on the flow required (always going to larger
filter size).
|
De
Filter
sq-feet |
Cart
Filter
sq-feet |
Sand
Filter
sq-feet |
Design
Flow Rate (gpm) |
Turnover
in Gallons |
| 8
hours |
10
hours |
| |
25 |
|
25 |
12,000 |
15,000 |
| |
|
1.75 |
35 |
16,800 |
21,000 |
| |
|
2.20 |
44 |
21,200 |
26,400 |
| 24 |
|
|
48 |
23,040 |
28,800 |
| |
50 |
|
50 |
24,000 |
30,000 |
| |
|
2.64 |
52 |
24,960 |
31,200 |
| |
|
3.13 |
62 |
29,760 |
37,200 |
| 36 |
|
|
72 |
34,560 |
43,200 |
| |
75 |
|
75 |
36,000 |
45,000 |
| 48 |
|
|
96 |
46,080 |
57,600 |
| |
|
4.91 |
98 |
47,040 |
58,800 |
| |
100 |
|
100 |
48,000 |
60,000 |
| 60 |
|
|
120 |
57,600 |
72,000 |
| 72 |
|
|
120 |
57,600 |
72,000 |
| |
150 |
|
150 |
72,000 |
90,000 |
|
| Numbers in tables represent typical
filter information. Consult specific filter performance data
for your filter. |
