SECTION
3 N.P.S.H.
SECTION 3
PAGE 1
WHAT IS
N.P.S.H.?
SECTION 3
PAGE 2
N.P.S.H.
NET POSITIVE SUCTION HEAD
Refers to the amount of atmospheric pressure to PUSH liquid into a
pump.
There are two values of N.P.S.H. to consider:
1. N.P.S.H. A = Available N.P.S.H. is a function of the system in which
the pump operates. It can be calculated for any installation.
Any pump installation, to operate successfully, must have an
available N.P.S.H.
2. N.P.S.H. R = Required N.P.S.H. is a function of the pump design.
It varies between different makes of pumps, between different
pumps of the same make and varies with the capacity and speed
of any one pump. This value can be found on most pump
performance curves or can be supplied by the pump
manufacturer.
SECTION 3
PAGE 3-A
N.P.S.H.
NET POSITIVE SUCTION HEAD
Refers to the amount of atmospheric pressure to PUSH liquid into a
pump.
There are two values of N.P.S.H. to consider:
1. N.P.S.H. A = Available N.P.S.H. is a function of the system in which
the pump operates. It can be calculated for any installation.
Any pump installation, to operate successfully, must have an
available N.P.S.H.
2. N.P.S.H. R = Required N.P.S.H. is a function of the pump design.
It varies between different makes of pumps, between different
pumps of the same make and varies with the capacity and speed
of any one pump. This value can be found on most pump
performance curves or can be supplied by the pump
manufacturer.
SECTION 3
PAGE 3-B
N.P.S.H.
NET POSITIVE SUCTION HEAD
Refers to the amount of atmospheric pressure to PUSH liquid into a
pump.
There are two values of N.P.S.H. to consider:
1. N.P.S.H. A = Available N.P.S.H. is a function of the system in which
the pump operates. It can be calculated for any installation.
Any pump installation, to operate successfully, must have an
available N.P.S.H.
2. N.P.S.H. R = Required N.P.S.H. is a function of the pump design.
It varies between different makes of pumps, between different
pumps of the same make and varies with the capacity and speed
of any one pump. This value can be found on most pump
performance curves or can be supplied by the pump
manufacturer.
SECTION 3
PAGE 3-C
NET POSITIVE SUCTION HEAD AVAILABLE
14.7 P.S.I. AT SEA LEVEL OR 33.96 FEET OF WATER
DEDUCTIONS FROM ATMOSPHERIC PRESSURE
ATMOSPHERIC PRESSURE
A - ELEVATION: As you go up in elevation
(from sea level) atmospheric
pressure will decrease.
B - VAPOR PRESSURE: Varies with type
of liquid & liquid temperature.
14.7 P.S.I.
OR
33.96 FEET OF WATER
C - SAFETY FACTOR: 2 feet for water &
water like products & 3 feet for
petroleum products
D - N.P.S.H. R: Varies with pump design &
flow rate. Found on pump
performance curve.
33.96'
E - FRICTION LOSSES: Losses through the
suction piping & fittings. Friction
losses varies with pipe size, type
& flow rate.
F - STATIC SUCTION LIFT: From centerline
of pump suction to pump off level.
AFTER THE DEDUCTIONS OF A, B, C, D, E & F
FROM ATMOSPHERIC PRESSURE, N.P.S.H. A.
MUST BE A POSITIVE NUMBER.
SECTION 3
PAGE 4
Pump Off
33.96 Ft. of Water
- Total Deductions
N.P.S.H.A
(N.P.S.H.A Must Be A Positive
Value For System To Work.)
SECTION 3
PAGE 5
NET POSITIVE SUCTION
HEAD REQUIRED
• Every pump has a required N.P.S.H.
• N.P.S.H. R is a function of pump design.
• N.P.S.H. R will be on most pump manufacturer’s
performance curves.
• N.P.S.H. R will be provided to you by the
manufacturer.
SECTION 3
PAGE 6
SECTION 3
PAGE 7
HOW TO COMPUTE THE
NET POSITIVE SUCTION HEAD
Based on a model T4A60-B pump, compute the
net positive suction head (N.P.S.H.) for the
following application.
340 G.P.M., 10' static lift, 25' of 4" D.I. pipe (C=120).
The pump will be located in Denver, Colorado
(5000 Ft. above sea level).
The liquid is 75 deg. F.
SECTION 3
PAGE 8-A
HOW TO COMPUTE THE
NET POSITIVE SUCTION HEAD
(continued)
A
Atmospheric Pressure at Sea Level
=
33.96 Ft.
__________
B
Atmospheric Pressure ( corrected to 5000 Ft. )
=
__________ Ft.
C
Atmospheric Pressure Available at Job Site
=
__________ Ft.
Deductions From Available Atmospheric Pressure:
D
1. Total Dynamic Suction Lift
= ________ Ft.
2. Vapor Pressure of Liquid
= ________ Ft.
3. Safety Factor (Atmospheric
Pressure Will Vary at Each
Location).
= ________ Ft.
Total Net Deductions From Available
Atmospheric Pressure ( Total 1,2 & 3 )
➛
__________ Ft.
E
N.P.S.H. Available ( Subtract D From C )
________ Ft.
F
N.P.S.H. Required ( See Performance Curve )
________ Ft.
G
N.P.S.H. Excess Available ( Subtract F From E )
________ Ft.
Note 1: Items E and F cannot be determined until pump is selected.
SECTION 3
PAGE 8-B
ATMOSPHERIC PRESSURE
CONDITIONS ELEVATIONS
ABOVE SEA LEVEL
ALTITUDE
ABOVE SEA
LEVEL IN
FEET
ALTITUDE
ABOVE SEA
LEVEL IN
METERS
REDUCTION
TO MAXIMUM
PRACTICAL
DYNAMIC LIFT
IN FEET
BAROMETRIC
READING
MILLIMETERS
MERCURY
EQUIVALENT
HEAD IN FEET
OF WATER
29.921
756
33.96
10.351
EQUIVALENT
HEAD IN
METERS OF
WATER
0
1000
304.8
1.2
.366
28.86
733
32.76
9.985
2000
609.6
2.33
.725
27.82
707
31.58
9.626
3000
914.4
3.53
1.076
26.81
681
30.43
9.275
4000
1219.2
4.63
1.411
25.84
656
29.33
8.490
5000
1524
5.71
1.74
24.89
632
28.25
8.611
6000
1828.8
6.74
2.054
23.98
609
27.22
8.297
7000
2133.6
7.75
2.362
23.09
586
26.21
7.989
8000
2438.4
8.74
2.664
22.22
564
25.22
7.687
PAGE 9
0
BAROMETRIC
READING
INCHES OF
MERCURY
0
SECTION 3
0
REDUCTION
TO MAXIMUM
PRACTICAL
DYNAMIC LIFT
IN METERS
FRICTION LOSS OF WATER IN FEET PER 100 FEET LENGTH OF PIPE.
BASED ON WILLIAMS & HAZEN FORMULA USING CONSTANT 100.
SIZES OF STANDARD PIPE IN INCHES.
1/2" Pipe
U.S.
Loss
Vel.
Gals.
in
Per min. ft. per
Sec. feet
2
4
6
8
10
2.10
4.21
6.31
8.42
10.52
7.4
27.0
57.0
98.0
147.0
12
15
18
20
25
30
35
3/4" Pipe
1" Pipe
Vel.
ft. per
Sec.
Loss
in
feet
Vel.
ft. per
Sec.
1.20
2.41
3.61
4.81
6.02
1.9
7.0
14.7
25.0
38.0
1.49
2.23
2.98
3.72
7.22 53.0
9.02 80.0
10.84 108.2
12.03 136.0
40
45
50
55
60
65
Loss
in
feet
3" Pipe
4" Pipe
5" Pipe
Vel.
Vel. Loss
ft. per
in ft. per
Sec.
Sec. feet
6" Pipe
Loss
in
feet
Vel. Loss
ft. per
in
Sec. feet
U.S.
Gals.
Per min.
.86
1.29
1.72
2.14
.57
1.20
2.03
3.05
.63
.94
1.26
1.57
.26
.56
.95
1.43
.61
.82
1.02
.20
.33
.50
.52
.65
.11
.17
.45
.07
2
4
6
8
10
4.46 16.4
5.60 25.0
6.69 35.0
7.44 42.0
9.30 64.0
11.15 89.0
13.02 119.0
2.57
3.21
3.86
4.29
5.36
6.43
7.51
4.3
6.5
9.1
11.1
16.6
23.0
31.2
1.89
2.36
2.83
3.15
3.80
4.72
5.51
2.01
3.00
4.24
5.20
7.30
11.00
14.70
1.23
1.53
1.84
2.04
2.55
3.06
3.57
.79
1.08
1.49
1.82
2.73
3.84
5.10
.78
.98
1.18
1.31
1.63
1.96
2.29
.23
.36
.50
.61
.92
1.29
1.72
.54
.68
.82
.91
1.13
1.36
1.59
.10
.15
.21
.25
.38
.54
.71
.51
.64
.77
.89
.06
.09
.13
.17
.49
.57
.04
.06
12
15
18
20
25
30
35
14.88 152.0
8.58
9.65
10.72
11.78
12.87
13.92
40.0
50.0
60.0
72.0
85.0
99.7
6.30
7.08
7.87
8.66
9.44
10.23
18.80
23.20
28.40
34.00
39.60
45.90
4.08
4.60
5.11
5.62
6.13
6.64
6.60
8.20
9.90
11.80
13.90
16.10
2.61
2.94
3.27
3.59
3.92
4.24
2.20
2.80
3.32
4.01
4.65
5.40
1.82
2.04
2.27
.245
2.72
2.89
.91
1.15
1.38
1.58
1.92
2.17
1.02
1.15
1.28
1.41
1.53
1.66
.22
.28
.34
.41
.47
.53
.65
.73
.82
.90
.98
1.06
.08
.09
.11
.14
.16
.19
.57
.62
.68
.74
.04
.05
.06
.076
40
45
50
55
60
65
15.01
16.06
17.16
18.21
19.30
113.0
129.0
145.0
163.8
180.0
11.02
11.80
12.59
13.38
14.71
14.95
53.00
60.00
68.00
75.00
84.00
93.00
7.15
7.66
8.17
8.68
9.19
9.70
18.40
20.90
23.70
26.50
29.40
32.60
4.58
4.91
5.23
5.56
5.88
6.21
6.20
7.10
7.90
8.10
9.80
10.80
3.18
3.33
3.63
3.78
4.09
4.22
2.57
3.00
3.28
3.54
4.08
4.33
1.79
1.91
2.04
2.17
2.30
2.42
.63
.73
.81
.91
1.00
1.12
1.14
1.22
1.31
1.39
1.47
1.55
.21
.24
.27
.31
.34
.38
.79
.85
.91
.96
1.02
1.08
.08
.10
.11
.12
.14
.15
70
75
80
85
90
95
15.74
17.31
18.89
20.46
22.04
102.00
122.00
143.00
166.00
190.00
10.21
11.23
12.25
13.28
14.30
15.32
35.80
42.90
50.00
58.00
67.00
76.00
6.54
7.18
7.84
8.48
9.15
9.81
12.00
14.50
16.80
18.70
22.30
25.50
4.54
5.00
5.45
5.91
6.35
6.82
4.96
6.00
7.00
8.10
9.20
10.50
2.55
2.81
3.06
3.31
3.57
3.82
1.22
1.46
1.72
1.97
2.28
2.62
1.63
1.79
1.96
2.12
2.29
2.45
.41
.49
.58
.67
.76
.88
1.13
1.25
1.36
1.47
1.59
1.70
.17
.21
.24
.27
.32
.36
100
110
120
130
140
150
16.34
17.36
18.38
19.40
20.42
22.47
86.00
96.00
107.00
118.00
129.00
154.00
10.46
11.11
11.76
12.42
13.07
14.38
29.00
34.10
35.70
39.60
43.10
52.00
7.26
7.71
8.17
8.63
9.08
9.99
11.80
13.30
14.00
15.50
17.80
21.30
4.08
4.33
4.60
4.84
5.11
5.62
2.91
3.26
3.61
4.01
4.40
5.20
2.61
2.77
2.94
3.10
3.27
3.59
.98
1.08
2.04
1.35
1.48
1.77
1.82
1.92
1.82
2.16
2.27
2.50
.40
.45
.50
.55
.62
.73
160
170
180
190
200
220
15.69 61.00
16.99 70.00
18.30 81.00
19.61 92.00
20.92 103.00
22.22 116.00
10.89
11.80
12.71
13.62
14.52
15.43
25.10
29.10
33.40
38.00
42.80
47.90
6.13 6.20
6.64 7.20
7.15 8.20
7.66 9.30
8.17 10.50
8.68 11.70
3.92
4.25
4.58
4.90
5.23
5.54
2.08
2.41
2.77
3.14
3.54
3.97
2.72
2.95
3.18
3.40
3.64
3.84
.87
1.00
1.14
1.32
1.47
1.62
240
260
280
300
320
340
23.53 128.00
24.84 142.00
26.14 156.00
16.34 53.00
17.25 59.00
18.16 65.00
20.40 78.00
22.70 98.00
24.96 117.00
9.19
9.69
10.21
11.49
12.77
14.04
13.10
14.00
16.00
19.80
24.00
28.70
5.87
6.19
6.54
7.35
8.17
8.99
4.41
4.86
5.40
6.70
8.10
9.60
4.08
4.31
4.55
5.11
5.68
6.25
1.83
2.00
2.20
2.74
3.36
3.96
360
380
400
450
500
550
27.23 137.00
15.32
16.59
17.87
19.15
20.42
21.70
33.70
39.00
44.90
51.00
57.00
64.00
9.80
10.62
11.44
12.26
13.07
13.89
11.30
13.20
15.10
17.20
19.40
21.70
6.81
7.38
7.95
8.50
9.08
9.65
4.65
5.40
6.21
7.12
7.96
8.95
600
650
700
750
800
850
22.98 71.00 14.71
15.52
16.34
17.97
19.61
24.00
26.70
29.20
34.90
40.90
10.20
10.77
11.34
12.48
13.61
14.72
10.11
11.20
12.04
14.55
17.10
18.40
900
950
1000
1100
1200
1300
15.90 22.60
17.02 25.60
18.10 26.90
1400
1500
1600
1800
2000
2200
2.14
4.55
7.8
11.7
.90
.96
.08
.09
160
170
180
190
200
220
1.02
1.08
1.15
1.21
1.28
1.40
.10
.11
.13
.14
.15
.18
.90
.06
240
260
280
300
320
340
1.53
1.66
1.79
1.91
2.05
2.18
.22
.25
.28
.32
.37
.41
.98
1.06
1.15
1.22
1.31
1.39
.07
.08
.09
.11
.12
.14
360
380
400
450
500
550
2.30
2.43
2.60
2.92
3.19
3.52
.45
.50
.54
.68
.82
.97
1.47
1.55
1.63
1.84
2.04
2.25
.15
.17
.19
.23
.28
.33
1.08
1.14
1.28
1.42
1.56
.069
.075
.95
.113
.136
600
650
700
750
800
850
3.84
4.16
4.46
4.80
5.10
5.48
1.16
1.34
1.54
1.74
1.97
2.25
2.45
2.65
2.86
3.06
3.26
3.47
.39
.45
.52
.59
.66
.75
1.70
1.84
1.99
2.13
2.27
2.41
900
950
1000
1100
1200
1300
5.75
6.06
6.38
7.03
7.66
8.30
2.46
2.71
2.97
3.55
4.17
4.85
3.67
3.88
4.08
4.49
4.90
5.31
.83
.91
1.03
1.19
1.40
1.62
1400
1500
1600
1800
2000
2200
8.95
9.58
10.21
11.50
12.78
14.05
5.50
6.31
7.00
8.78
10.75
12.82
5.71
6.12
6.53
7.35
8.16
8.98
2400
2600
2800
3000
3200
3500
15.32
15.06
Loss
in
feet
10" PIPE
Vel.
ft. per
Sec.
Loss
in
feet
24.51 182.00
26.55 211.00
12" PIPE
14" PIPE
1.04
1.15
.06
.07
.159
.19
.22
.24
.27
.31
1.25
1.37
1.46
1.58
1.67
1.79
.08
.09
.10
.11
.13
.14
1.36
.08
2.56
2.70
2.84
3.13
3.41
3.69
.34
.38
.41
.49
.58
.67
1.88
2.00
2.10
2.31
2.52
2.71
.16
.18
.19
.23
.27
.32
1.44
1.52
1.60
1.76
1.92
2.08
.084
.095
.10
.12
.14
.17
1.87
2.13
2.39
2.95
3.59
4.24
3.98
4.26
4.55
5.11
5.68
6.25
.78
.89
.98
1.21
1.49
1.81
2.92
3.15
3.34
3.75
4.17
4.59
.36
.41
.47
.58
.71
.84
2.24
2.39
2.56
2.87
3.19
3.51
9.80 5.04
10.61 5.81
11.41 6.70
12.24 7.62
13.05 7.80
14.30 10.08
6.81
7.38
7.95
8.52
9.10
9.95
2.08
2.43
2.75
3.15
3.51
4.16
5.00
5.47
5.84
6.01
6.68
7.30
.99
1.17
1.32
1.49
1.67
1.97
15.51 13.40
10.80
11.92
12.78
14.20
4.90
5.88
6.90
8.40
7.98
8.76
9.45
10.50
11.55
12.60
13.65
14.60
6500
7000
8000
9000
10000
12000
14000
16000
18000
20000
SECTION 3
2 1/2" Pipe
2" Pipe
Vel.
ft. per
Sec.
8" PIPE
3800
4200
4500
5000
5500
6000
1 1/2" Pipe
Loss
in
feet
70
75
80
85
90
95
100
110
120
130
140
150
1 1/4" Pipe
Vel.
ft. per
Sec.
PAGE 10
Vel.
ft. per
Sec.
Loss
in
feet
Vel.
ft. per
Sec.
Loss
in
feet
16" PIPE
20" PIPE
1.02
1.12
1.23
1.33
.04
.04
.05
.06
.19
.21
.24
.30
.37
.44
1.43
1.53
1.63
1.84
2.04
2.25
.064
.07
.08
.10
.12
.15
3.83
4.15
4.47
4.79
5.12
5.59
.52
.60
.68
.78
.88
1.04
2.45
2.66
2.86
3.08
3.27
3.59
2.36
2.77
3.22
3.92
4.65
5.50
6.07
6.70
7.18
8.01
8.78
9.58
1.20
1.44
1.64
2.03
2.39
2.79
6.45
7.08
10.39
11.18
12.78
14.37
15.96
24" PIPE
30" PIPE
1.28
1.42
1.56
.04
.05
.06
.17
.20
.23
.27
.30
.35
1.70
1.84
1.98
2.13
2.26
2.49
.07
.08
.09
.10
.12
.14
1.09
1.16
1.27
1.37
1.46
1.56
.02
.027
.03
.037
.041
.047
2400
2600
2800
3000
3200
3500
3.88
4.29
4.60
5.13
5.64
6.13
.41
.49
.56
.68
.82
.94
2.69
2.99
3.20
3.54
3.90
4.25
.17
.20
.22
.27
.33
.38
1.73
1.91
2.04
2.26
2.50
2.73
.05
.07
.08
.09
.11
.13
3800
4200
4500
5000
5500
6000
3.32 6.64
3.70 7.15
4.74 8.17
5.90 9.20
7.19 10.20
12.25
1.10
1.25
1.61
2.01
2.44
3.41
4.61
4.97
5.68
6.35
7.07
8.50
.45
.52
.66
.81
.98
1.40
2.96
3.18
3.64
4.08
4.54
5.46
.15
.17
.23
.28
.33
.48
6500
7000
8000
9000
10000
12000
14.30
4.54
9.95
11.38
12.76
14.20
1.87
2.40
2.97
3.60
6.37
7.28
8.18
9.10
.63
.81
1.02
1.23
14000
16000
18000
20000
VAPOR PRESSURE
WATER CHARACTERISTICS
TEMPERATURE
0F
40
0C
VAPOR PRESSURE
KPa
P.S.I.
ABSOLUTE ABSOLUTE
4.4
FEET
METERS
SPECIFIC
GRAVITY
.1217
.8391
0.281
.0856
1.0000
50
10
.1781
1.2280
0.4115
.1254
.9997
60
15.6
.2563
1.7671
0.592
.1804
.9990
70
21.1
.3631
2.5035
0.815
.2484
.9980
80
26.7
.5069
3.4950
1.17
.3566
.9966
90
32.2
.6982
4.8140
1.612
.14913
.9950
100
37.8
.9492
6.5445
2.191
.6678
.9931
110
43.3
1.275
8.7909
2.942
.8967
.9910
120
48.9
1.692
11.6660
3.91
1.1918
.9888
130
54.4
2.223
15.3271
5.145
1.5682
.9857
140
60
2.889
19.9191
6.675
2.0345
.9833
150
65.6
3.718
25.6349
8.56
2.6091
.9803
160
71.1
4.741
32.6882
10.945
3.3360
.9773
170
76.7
5.992
41.3136
13.84
4.2184
.9738
180
82.2
7.510
51.7800
17.35
5.2883
.9702
190
87.8
9.339
64.3905
21.55
6.5684
.9660
200
93.3
11.5
79.4970
26.65
8.1229
.9632
210
98.9
14.12
97.3546
32.6
9.9365
.9592
220
104.4
17.19
118.5216
39.7
12.1006
.9552
SECTION 3
PAGE 11
REPRIMING LIFTS
TOTAL HEAD
PSI
FT
60
140
56
130
52
120
110
44
100
CURVE
T4A-B-4
IMPELLER
10528
MODEL
T4A-B
Note:
Select performance within
operating range of curve.
195
0R
PM
35%
185
0
SIZE
OPE
R
RANATING
GE
40
45
SP. GR.
55%
155
0
28
1450
BH
P[
25
20
[1
,9
8,6
KW
]
1350
40
1050
30
950
850
]
PAGE 12
75
70
65
60
55
64
60
22
21
56
48
17
44
16
15
40
14
36
13
32
11
28
20
7
16
6
12
X10
5
12
4
8
3
2
4
1
0
CUBIC METRES
PER HOUR
M
10
8
6
4
10
2]
50
45
30
25
20
15
10
5
0
LITRES
PER SECOND
SECTION 3
5]
[5,6
7]
3[2,
20
7.5
5[3,
]
X10
0
U.S. GALLONS
PER MINUTE
2[1,
1[,75]
10
0
NPSH@1950RPM
0
40
0
750
650
9
10
7,5
35
4
30
10[
24
8
4
20
FT
15
[11
,2]
8
12
NPSH
]
100
1150
20
[14
,9
23
50
20
16
]
1250
24
95
60
90
28
85
80
70
8
VARIOUS
90
32
12
RPM
55
165
0
20
40
24
16
1.0
9 3/4”
0
36
20
IMP. DIA.
Consult factory on operating conditions
above 1500 rpm when TDSL exceeds 19 ft.
50
175
4”X4”
80
28
48
10525B
52
32
3.00”/[76.2] DIA. SPHERICAL SOLIDS
VOLUTE
19
36
PERFORMANCE CURVE
1250-1950
25
7.6
Figure NPSH required prior to using above table. DO NOT
use as available Suction Lifts.
44
40
1150
24
7.3
650
22
6.7
18
M
950
19
5.8
850
16
4.9
750
8
2.4
650
5
1.5
RPM
FEET
METERS
0
2
0
HOW TO COMPUTE THE
NET POSITIVE SUCTION HEAD
Based on a model T4A60-B pump, compute the
net positive suction head (N.P.S.H.) for the
following application.
550 G.P.M., 10' static lift, 25' of 4" D.I. pipe (C=120).
The pump will be located in Denver, Colorado
(5000 Ft. above sea level).
The liquid is 75 deg. F.
SECTION 3
PAGE 13-A
HOW TO COMPUTE THE
NET POSITIVE SUCTION HEAD
(continued)
A
Atmospheric Pressure at Sea Level
=
33.96 Ft.
__________
B
Atmospheric Pressure ( corrected to 5000 Ft. )
=
__________ Ft.
C
Atmospheric Pressure Available at Job Site
=
__________ Ft.
Deductions From Available Atmospheric Pressure:
D
1. Total Dynamic Suction Lift
= ________ Ft.
2. Vapor Pressure of Liquid
= ________ Ft.
3. Safety Factor (Atmospheric
Pressure Will Vary at Each
Location).
= ________ Ft.
Total Net Deductions From Available
Atmospheric Pressure ( Total 1,2 & 3 )
➛
__________ Ft.
E
N.P.S.H. Available ( Subtract D From C )
________ Ft.
F
N.P.S.H. Required ( See Performance Curve )
________ Ft.
G
N.P.S.H. Excess Available ( Subtract F From E )
________ Ft.
Note 1: Items E and F cannot be determined until pump is selected.
SECTION 3
PAGE 13-B
To Section 4