Pumping Station Desing - Second Edition by Robert L. Sanks, George Tchobahoglous, Garr M. Jones
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Geometric properties
of
circular segments
are
shown
in
Figure
B-4.
As
explained
in
Section
3-5,
the
Manning
equation,
although accurate
for
pipes
flowing
full,
is in
error
by as
much
as 25% for
pipes
flowing
partly
full.
The
comparison between
Manning's
data
and
extensive
field
data
as
depicted
by
Camp
[8] is
shown
in
Figure
B-
5.
Wheeler
[9]
developed
an
empirical equation that
fits
Camp's
curve
of field
data within
an
error
of
less
than
2%,
and
comparative values
of
Manning's
data
and
observed (actually Wheeler's) data
are
given
in
Table
B-8.
The
velocities required
to
clear
or
scour
air
pockets
from
a
pipe that slopes downward, given
in
Table
B-9,
were
computed
by
Wheeler
[10]
from
an
equation (developed
by
Wisner, Mohsen,
and
Kouwen
[11])
that
can
be
rearranged
to
v
=
^D(0.825
+
0.25
Vsirie)
(B-I)
where
v is the
velocity required,
D is the ID of the
pipe,
and 6 is
angle
of the
downward gradient
of the
pipe
pro-
file. The use of
velocity
as a
mechanism
for air
bubble removal
was not
common
in
1996.
Until
it has
become
common
practice, users
are
advised
to
study
the
literature—at
least Edmunds
[12],
Walski
et
al.
[13],
and
Falvey
[14]
to
gain
confidence
in the
method.
Figure
B-4.
Geometric properties
of
partly
full
pipes
and
velocity
and
discharge
based
on the
uncorrected Manning
equation.
Figure
B-5. Hydraulic elements
of
circular pipes
as
open channels. Observed
versus
Manning
values. After Camp
[2].
Table
B-8. Comparison
of
Computed Values
of
Velocity,
Depth,
Area,
and
Flow
in
Open
Channels.
Manning
versus
Observed Values. After Wheeler
[1O].
All
values
in
percent
of
those
for a
full
pipe.
Q =
flow,
y =
depth,
V
=
velocity,
A =
wetted area.
Manning
Observed
Manning
Observed
Q
~y
V
A"
~y
V
A~
Q
~y
V
A~
~y
V
A~
0000000
50 50 100 50 57 86 58
1
7 32 3 8 26 4 51 51 101 51 57 86 59
2 10 40 5 11 32 6 52 51 101 52 58 87 60
3
12 45 7 14 36 8 53 52 102 52
59
87 61
4 14 49 8 16 40 10 54 52 102 53 59 88 62
5 15 52 10 18 42 12 55 53 102 54 60 88 62
6 17 55 11 19 45 13 56 54 103 55 60 89 63
7 18 58 12 21 47 15 57 54 103 55 61 89 64
8 19 60 13 22 49 16 58 55 104 56 62 90 65
9 20 62 15 23 51 18 59 55 104 57 62 90 66
10
21 64 16 25 52 19 60 56 105 57 63 91 66
11
22 66 17 26 54 20 61 56 105 58 64 91 67
12
23 67 18 27 55 22 62 57 105 59 64 92 68
13
24 69 19 28 57 23 63 58 106 60 65 92 69
14
25 71 20 29 58 24 64 58 106 60 65 92 69
15
26 72 21 30 59 25 65 59 107 61 66 93 70
16
27 73 22 31 61 26 66 59 107 62 67 93 71
17
28 75 23 32 62 28 67 60 107 63 67 94 72
18
29 76 24 33 63 29 68 61 108 63 68 94 72
19
30 77 25 34 64 30 69 61 108 64 69 94 73
20 30 78 26 35 65 31 70 62 108 65 69 95 74
21
31 79 27 36 66 32 71 62 109 65 70 95 75
22 32 80 27 36 67 33 72 63 109 66 71 96 75
23
33 81 28 37 68 34 73 63 109 67 71 96 76
24 33 82 29 38 69 35 74 64 110 68 72 96 77
25
34 83 30 39 69 36 75 65 110 68 72 97 78
26 35 84 31 40 70 37 76 65 110 69 73 97 78
27 36 85 32 41 71 38 77 66 110 70 74 97 79
28 36 86 33 41 72 39 78 66 111 71 74 98 80
29 37 87 34 42 73 40 79 67 111 71 75 98 81
30 38 87 34 43 73 41 80 68 111 72 76 99 81
31
38 88 35 44 74 42 81 68 111 73 76 99 82
32
39 89 36 44 75 43 82 69 112 74 77 99 83
33
40 90 37 45 76 44 83 70 112 74 78 100 83
34
40 90 38 46 76 45 84 70 112 75 78 100 84
35
41 91 38 46 77 46 85 71 112 76 79 100 85
36
42 92 39 47 78 46 86 72 113 77 80 101 86
37
42 93 40 48 78 47 87 72 113 77 81 101 86
38 43 93 41 49 79 48 88 73 113 78 81 101 87
39
43 94 42 49 80 49 89 74 113 79 82 101 88
40 44 94 42 50 80 50 90 74 113 80 83 102 89
41
45 95 43 51 81 51 91 75 113 80 84 102 89
42 45 96 44 51 81 52 92 76 114 81 84 102 90
43 46 96 45 52 82 53 93 76 114 82 85 103 91
44 46 97 46 53 83 53 94 77 114 83 86 103 92
45
47 97 46 53 83 54 95 78 114 84 87 103 92
46 48 98 47 54 84 55 96 79 114 84 88 103 93
47 48 99 48 55 84 56 97 79 114 85 89 104 94
48 49 99 49 55 85 57 98 80 114 86 90 104 95
49 49 100 49 56 85 58 99 81 114 87 91 104 95
50 50 100 50 57 86 58 100 82 114 88 92 104 96
Table
B-9.
Velocities
Required
3
to
Scour
Air
Pockets
from
Pipelines.
Values
computed
by
Wheeler
[4]
using
Equation
B-1
developed
by
Wisner,
Mohsen,
and
Kouwen
[5].
Velocities,
m/s
Velocities,
ft/s
Pipe
Pipe
diameter,
SI
°P
e
SI
°P
e
diameter,
mm
0% 5% 25% 45° 90° 0% 5% 25% 45° 90° in.
25
0.4 0.4 0.5 0.5 0.5 1.4 1.4 1.6 1.7 1.8 1
50
0.6 0.6 0.7 0.7 0.8 1.9 2.0 2.2 2.4 2.5 2
75
0.7 0.8 0.8 0.9 0.9 2.3 2.5 2.7 2.9 3.1 3
100
0.8 0.9 0.9 1.0 1.1 2.7 2.9 3.1 3.4 3.5 4
150 1.0 1.1 1.2 1.3 1.3 3.3 3.5 3.8 4.2 4.3 6
200 1.2 1.2 1.3 1.5 1.5 3.8 4.1 4.4 4.8 5.0 8
250 1.3 1.4 1.5 1.6 1.7 4.3 4.6 4.9 5.4 5.6 10
300 1.4 1.5 1.6 1.8 1.9 4.7 5.0 5.4 5.9 6.1 12
350 1.6 1.6 1.8 1.9 2.0 5.1 5.4 5.8 6.3 6.6 14
375 1.6 1.7 1.8 2.0 2.1 5.2 5.6 6.0 6.6 6.8 15
400 1.6 1.8 1.9 2.1 2.1 5.4 5.8 6.2 6.8 7.0 16
450 1.7 1.9 2.0 2.2 2.3 5.7 6.1 6.6 7.2 7.5 18
500 1.8 2.0 2.1 2.3 2.4 6.0 6.5 6.9 7.6 7.9 20
525 1.9 2.0 2.2 2.4 2.5 6.2 6.6 7.1 7.8 8.1 21
600 2.0 2.2 2.3 2.5 2.6 6.6 7.1 7.6 8.3 8.6 24
675 2.1 2.3 2.5 2.7 2.8 7.0 7.5 8.1 8.8 9.2 27
750 2.3 2.4 2.6 2.8 2.9 7.4 7.9 8.5 9.3 9.6 30
825 2.4 2.5 2.7 3.0 3.1 7.8 8.3 8.9 9.7
10.1
33
900 2.5 2.7 2.8 3.1 3.2 8.1 8.7 9.3
10.2 10.6
36
1050
2.7 2.9 3.1 3.4 3.5 8.8 9.4
10.1 11.0 11.4
42
1200
2.9 3.0 3.3 3.6 3.7 9.4
10.0 10.8 11.8 12.2
48
1500
3.2 3.4 3.7 4.0 4.1
10.5 11.2 12.0 13.1 13.6
60
1800
3.5 3.7 4.0 4.4 4.5
11.5 12.2 13.2 14.4 14.9
72
a
See
first
page
of
Appendix
B.
Practical considerations:
• Air
problems
do not
occur where
the
pipe
gradient
is
positive
in the
direction
of flow
[5].
•
Avoid excessive headloss
by
using smaller diameter pipe
(to
obtain higher velocities) only where gradient
is
flat
or
slopes downward.
• For air
scouring
to be
effective,
the
tabular velocities must occur frequently (e.g., daily
or
more
often).
• Air
release valves
in
small pipes
may be of
little
or no
value.
•
Blowback
from
clearing
air in
large pipes
may
cause surges that cannot
be
estimated.
See
Wisner, Mohsen,
and
Kouwen
[5].
Before
designing piping systems
for air
scouring,
it is
advisable
to
read "Air binding
in
pipes"
by
Edmunds
[6],
the
chapter
on
closed conduit
flow in
FaIvey
[14],
and,
for
wastewater,
"Hydraulics
of
corrosive
gas
pockets
in
force
mains"
by
Walski
et
al.
[13]
.
B-1.
References
1.
Ten-State Standards. Recommended
Standards
for
Sewage
Works.
Great Lakes-Upper Mississippi Board
of
Sanitary
Engineers, Health Education Service, Inc., Albany,
NY
(1978).
2.
DIPRA. Handbook
of
Ductile Iron Pipe,
6th ed.
Ductile Iron Pipe Research Association, Birmingham,
AL
(1984).
3.
ANSI
B36.10.
"Welded
and
Seamless Wrought Steel
Pipe."
American National Standards Institute,
New
York (updated
periodically).
4.
Lamont,
P. A.
"Common pipe
flow
formulas compared with
the
theory
of
roughness." Journal
of
the
American
Water
Works
Association,
73,
274-280
(May 1981).
5.
Peggs,
L. A.
Underground
Piping
Handbook. Robert
E.
Krieger
Publishing Company, Malabar,
FL
(1985).
6.
Miller,
W. T.
"Durability
of
cement-mortar linings
in
cast-iron
pipe."
Journal
of
the
American
Water
Works
Association,
57,
773-782
(June
1965).
7.
Moody,
L. F.
"Friction
factors
for
pipe
flow."
Transactions
of
the
American Society
of
Mechanical
Engineers,
66,
671-684
(November 1944).
8.
Camp,
T. R.
Discussion
of
"Determinations
of
Kutter's
n for
sewers partly
filled,"
Transactions
of
the
American
Society
of
Civil Engineers, 71(3) Part
2:240-245
(1944).
9.
Wheeler,
W.
PARTFULL®.
For a
free
copy
of
this computer program with instructions, send
a
formatted
1.4 MB,
3
1
I
2
-
in.
diskette
and a
stamped self-addressed mailer
to 683
Limekiln Road, Doylestown,
PA
18906-2335.
10.
Wheeler,
W.,
Consulting Engineer, Doylestown,
PA.
Private communication (November
1995).
11.
Wisner,
P. E. F. N.
Mohsen,
and N.
Kouwen. "Removal
of air
from
waterlines
by
hydraulic means." Proceedings
of
the
American Society
of
Civil
Engineers, Journal
Hydraulic
Div.
HY2
101,
243-257
(February 1975).
12.
Edmunds,
R. C.
"Air binding
in
pipes."
Journal
of
the
American
Water
Works
Association.
71(5),
272-277
(May 1979).
13.
Walski,
T.
M.,
T. S.
Barnhart,
J. M.
Driscoll,
and R. M.
Yencha. "Hydraulics
of
corrosive
gas
pockets
in
force mains."
Water
Environment Research
60
(6):772-778
(September/October
1994).
14.
Falvey,
H. T.
Air-Water
Flow
in
Hydraulic
Structures (Chapter
on
Closed Conduit Flow). U.S. Dept.
of
Interior, Bureau
of
Reclamation Engineering Monograph
41.
Superintendent
of
Documents, Washington, D.C. (1980).
B-2.
Supplementary
Reading
1.
Benedict,
R. P.
Fundamentals
of
Pipe
Flow. John Wiley,
New
York
(1980).
2.
Culp/Wesner/Culp.
Handbook
of
Public
Water
Systems,
834-870.
Van
Nostrand
Reinhold,
New
York
(1986).
3.
Flow
of
Fluids
Through
Valves,
Fittings,
and
Pipe, Technical Paper
No.
410. Crane Co.,
New
York
(1981
j.
4.
Hydraulics
and
Useful
Information.
FMC
Bulletin
9900,
Clow Corp., Melrose Park,
IL
(1973).
5.
Hydraulic
Institute Engineering Data Book,
2nd ed.
Hydraulic Institute,
Parsippany,
NJ
(1990).
6.
Idel'Chik,
I. E.
Handbook
of
Hydraulic
Resistance.
Gosudarstvennoe
Energeticheskoe Izdatel'stro, Moskva-Leningrad
(1960); English translation, Israel Program
for
Scientific Translations, Ltd.,
U. S.
Department
of
Commerce, Springfield,
VA
(1966).
7.
Miller,
D. S.
"Internal
flow
systems," BHRA Fluid Engineering Series, Vol.
5,
British Hydromechanics Research
Association,
Cranfield,
Bedford, United Kingdom (1978).
8.
Chow,
V. T.
Open-Channel
Hydraulics.
McGraw-Hill,
New
York
(1959,
reissued
1988).
Appendix
C
Typical
Specifications
for
Pumps
and
Drivers
DAVID
L.
EISENHAUER
GARR
M.
JONES
CONTRIBUTORS
Richard
O.
Garbus
Philip
A.
Huff
Melvin
P.
Landis
Earle
C.
Smith
Morton
Wasserman
[The
format,
headings,
and
numbering system
in
this
appendix
generally
follow
the
three-part section format
in
the
recommendations
of the
Construction Specification Institute Manual
of
Practice Document MP-2-2.
SI
units
were
not
incorporated
in
this document.
The
following
is an
actual
specification
quoted
from
a
project
for
which
bids were received
in the
spring
of
1985. Four
qualifying
proposals were
received
for the
specified
equip-
ment. None
of
the
candidate suppliers took serious exception
to the
specification
requirements.
Codes
and
standards
are
given here
in
abbreviated form. Titles
are
listed
in
Appendix
E, and
publishers'
addresses
are
given
in
Appendix
F.]
SECTION 11302
CUSTOM ENGINEERED HEAVY-DUTY VERTICAL NONCLOG
CENTRIFUGAL PUMPING UNITS
PART
1—GENERAL
1.01
DESCRIPTION
A.
SCOPE:
This
section specifies custom engineered heavy-duty wastewater pumping units. Each pumping unit consists
of
a
vertical nonclog centrifugal pump, vertical drive
shaft
and
couplings, squirrel-cage induction motor suitable
for
variable-frequency speed control,
and all
necessary appurtenances
to
provide complete pumping systems.
The
contractor shall require that
the
pumping units specified herein
are
supplied
by a
single manufacturer.
1.01
B
B.
TYPE:
Each
pump shall
be of the
vertical,
dry
pit, bottom suction volute casing, enclosed impeller, nonclog centrif-
ugal
type, designed
so
that
the
impeller
shaft
and
bearings
can be
removed without disturbing
the
connecting
piping
or
casing.
The
pump casing shall
be
pedestal mounted
on a
common cast-iron
or
fabricated steel base
with
sufficiently
large openings
to
permit access
to the
pump suction line.
C.
EQUIPMENT LIST:
Pumps
Motors
Pumping Station
X
Sewage
pump
1
P331,001
M331,001
Sewage
pump
2
P331,002
M331,002
Sewage pump
3
P331,003
M331,003
Sewage pump
4
P331,004
M331,004
Pumping Station
Y
Sewage
pump
1
P330,001
M330,001
Sewage pump
2
P330,002
M330,002
Sewage pump
3
P330,003
M330,003
Sewage pump
4
P330,004
M330,004
D.
REFERENCE SPECIFICATIONS:
This section contains reference
to the
following
specifications
for
more detailed requirements which must
be
complied
with
in
providing
the
equipment covered under this section.
For
reference,
the
Contractor's attention
is
directed
to the
following sections included
as
part
of
this project manual:
Section
Title
10030
Noise requirements
and
Controls
1100
General requirements
for
Equipment
11020
Vibration
and
Dynamic Requirements
16158
Adjustable Frequency Drives
1.02
QUALITYASSURANCE
A.
REFERENCES:
This section references
the
following
documents. They
are a
part
of
this section
as
specified
and
modified.
In
case
of
conflict
between
the
requirements
of
this section
and
those
of the
listed documents,
the
requirements
of
this
section shall prevail.
Reference
Title
Standards
of the
Hydraulic Institute, latest
edition
AFBMA
Std
11-78
Load
and
Fatigue
Life
for
Roller Bearings
ASTM A48-83 Gray Iron Castings
ASTM A276-83 Stainless
and
Heat-Resisting Steel Bars
and
Shapes
ASTM A36-84a Structural Steel
ASTM A322-82 Steel Bars, Alloy, Standard Grades
NEMA
MGI-78
Motors
and
Generators
UL
1004-84
Motors,
Electric
ANSI/IEEE
112-84
Test Procedures
for
Polyphase Induction Motors
and
Generators
1.02B
B.
UNIT
RESPONSIBILITYAND
COORDINATION:
The
contractor shall cause
all
equipment specified under this section
to be
furnished
by the
pump manu-
facturer
who
shall
be
responsible
for the
adequacy
and
compatibility
of all
pumping unit components.
Any
component
of
each complete pumping unit
not
provided
by the
pump manufacturer shall
be
designed,
fabri-
cated, tested,
and
installed
by
factory-authorized representatives experienced
in the
design
and
manufacture
of
variable-speed pumping equipment. This requirement, however, shall
not be
construed
as
relieving
the
Contractor
of the
overall responsibility
for
this portion
of the
work.
Additionally,
the
Contractor shall cause
the
pump manufacturer
and its
suppliers
to
coordinate
design
of the
pumping
units with
the
manufacturer
of the
adjustable-speed drive equipment
and
controls such that
all
equip-
ment
is
compatible
and
capable
of
achieving
the
performance requirements specified below.
[Author's
note:
Some contractors will
try to
circumvent
the
Unit
Responsibility requirement
in an
effort
to
save
costs.
To
forestall such
a
move,
the
Unit
Responsibility
specification
should
be
accompanied
by a
require-
ment/or
the
contractor
to
confirm
by
affidavit
that
the
specified
arrangement
has
been provided.
The
affidavit
should
be
signed
by the
authorized representatives
of the
contractor
and the
manufacturers
of the
principal
equipment
items under
the
penalty
of
perjury.]
C.
DESIGN REQUIREMENTS:
The
arrangement shown
on the
drawings
is
based
upon
the
best information available
to the
Engineer
at the
time
of
design
and is not
intended
to
show exact dimensions peculiar
to any
specific equipment unless otherwise
shown
or
specified. Therefore,
it may be
anticipated that
the
structural supports, foundations,
connected
piping
and
valves shown,
in
part
or in
whole,
may
have
to be
changed
in
order
to
accommodate
the
pumping equipment
furnished.
No
additional payment will
be
made
for
such changes.
All
necessary calculations
and
drawings
for
any
related redesign shall
be
submitted
to the
Engineer
for his
approval prior
to
beginning
the
work.
Pumping units shall
be
designed
to
operate
at
variable speed without cavitation
or
damaging vibration over
the
entire specified range
of flow and
head conditions. Pumping units shall
not
produce undue noise
or
vibra-
tions during reductions
in flow
from
the
specified operating capacity range
to
zero
flow.
[Authors
note: Noise
cannot
be
quantified
as it has
more
to do
with
quality
than magnitude.
An
expert,
used
to
listening
to
similar
pumps,
can
identify
"undue"
noise.
Vibration
is
also complex
and is, in
addition,
a
function
of the
support.
Again,
an
expert
can
determine whether vibration
is
"excessive."
Specifying
magnitude
of
either noise
or
vibra-
tion
is
futile.]
All
components shall
be
designed
to
safely
withstand forces resulting
from
flow
reversals,
up to 125
percent
of
maximum speed, within
the
pump during shutdowns caused
by
power failure.
The
Contractor shall
be
responsible
for
this coordination
and
shall ensure that
the
component parts
do not
interact
on
each other
to
pro-
duce unacceptable vibrations,
stresses,
or
undesirable conditions.
The
pump base shall
be
designed
for
anchor bolting
to a
concrete foundation, assuming that
the
pump, with-
out
restraints
at the
suction
and
discharge connections,
is
subjected
to a
displacing force equal
to
that developed
by
an
internal pressure equal
to
three times
shut-off
head
at
maximum operating speed.
The
motor shall
be
sup-
ported independently
on the
motor room
floor
above
and
shall
be
connected
to the
pump with
two
intermediate
shaft
lengths
as
shown
on the
drawings.
No
vertical hydraulic thrust shall
be
transmitted
to the floor
above
from
the
pumps below.
The
complete pumping unit shall
be
designed
to
operate without overload
on any
component
at any
point
along
the
pump's entire full-speed operating curve.
D.
OPERATING CONDITIONS:
[Authors'
note: although this
specification
is
silent
on
allowable maximum
speed,
the
authors
prefer
to
limit
speed
to
1150
revlmin
whenever possible.
1.02D
Each
pumping unit shall
be
capable
of
operating
at
infinitely
variable speeds
to
meet
the
following operating
conditions
outlined below:
Pumps
P331,001,
P331,002,
P330,001
and
P330,002
Operating Condition Pumping Station
X
Pumping Station
Y
Maximum Speed Operation
A
1
Capacity,
mgd
3.8 3.7
Total head, feet
166 169
B
2
Capacity,
mgd 2.7 2.9
Total head, feet
202 192
Operating
Condition Pumping Station
X
Pumping Station
Y
Reduced Speed Operation
C
3
Capacity,
mgd 0.5 0.5
Total head, feet
150 154
Pump
speed reduced reduced
D
4
Capacity,
mgd O O
Total head, feet
149 153
Pump
speed minimum minimum
Minimum
NPSH available
at any
specified conditions
31
30
Characteristics
Minimum pump efficiency
at
best efficiency points,
percent
71 71
Minimum
spherical solids-passing capacity diameter, inches 3-1/2 3-1/2
Maximum
full-load horsepower required
200 200
Pumps
P331,003,
P331,004,
P330,003
and
P330,004
Operating
Condition Pumping Station
X
Pumping
Station
Y
Maximum
Speed Operation
Al
Capacity,
mgd
10.8
11.0
Total head,
feet
172 169
B
2
Capacity,
mgd 9.0 9.9
Total head, feet
194 183
Reduced Speed Operation
C
3
Capacity,
mgd 4.4 4.3
Total head, feet
153 154
Pump speed reduced reduced
D
4
Capacity,
mgd O O
Total head, feet
149 153
Pump speed minimum minimum
Minimum
NPSH available
at any
specified condition
32 31
1.02D
Operating
Condition
Pumping Station
X
Pumping Station
Y
Characteristic
Minimum pump efficiency
at
best
efficiency
point,
percent
82 82
Minimum pump
solids-passing
capacity
diameter,
inches
4 4
Maximum
full
load
motor
horsepower
required
5
450 450
Notes
(see superscripts):
1.
Condition
A
shall
be
taken
as the
rated,
continuous-duty
operating condition.
2.
Condition
B is
presented
to
indicate
the
expected head capacity condition with pumps operating
in
parallel.
3.
Condition
C
represents
the
expected minimum sustained
flow,
continuous-duty
operating condition
for one
pump
operating
at
reduced speed.
4.
Condition
D
represents
the
expected momentary
flow
conditions
for one
pump operating
at
minimum speed.
The
pumps will
be
started
and
stopped against
a
closed discharge valve. This condition will occur
for a
short time
only—typically
less
than
45
seconds.
5. The
variable-speed control system will employ variable-frequency drives
to
vary
the
rpm
of the
squirrel-cage induction motor. Motors
shall
be
selected such that along
the
pump's full-speed curve
the
motor
is not
loaded
at
more than
90
percent
of the
motor's nameplate
rating
as a
result
of the
pump's
brake horsepower requirement
and
other power-absorbing accessories included
as a
part
of the
complete
pumping
unit.
E.
MASS ELASTIC SYSTEMS
AND
CRITICAL SPEEDS:
Each complete system, including pump, intermediate shafting, motor,
and all
appurtenances, shall have
no
dangerous critical
or
resonance frequencies
or
multiples
of
resonance frequencies within
20
percent above
and
35
percent below
the
speed range required
by the
pump
to
meet
the
specified operating conditions.
For the
purposes
of
design,
a
dangerous vibratory critical speed shall
be
defined
as one
which produces
a
tor-
sional stress exceeding
3500
psi.
The
Contractor shall
be
responsible
for the
analysis
of
critical speeds
and the
complete mass elastic system, which shall
be
analyzed
and
certified
by a
registered professional engineer regu-
larly
engaged
in
this type
of
work. Calculations shall
be
submitted
to the
Engineer
for
review prior
to
construc-
tion
of the
equipment. Nothing
in
this provision shall
be
construed
as
relieving
the
Contractor
of his
responsibility
for
this portion
of the
work.
F.
FACTORY TESTING:
1.
MATERIALS: Melt
and
strength tests
of the
nickel cast iron used
in the
manufacture
of the
pumps'
major
components shall
be
performed
in
accordance with
all
applicable ASTM standards.
The
Contractor shall furnish
the
Engineer with
five
certified copies
of the
results
of all
tests.
The
composition
and
relative physical properties
of
all
other component materials shall
be
submitted.
2.
HYDROSTATIC
TESTS:
Each pump shall
be
hydrostatically tested.
The
test pressure shall
be not
less
than
twice
the
shut-off
head
as
shown
on the
approved head-capacity curve passing through
or
above
the
rated
point (point
A). The
test procedure shall
be as
follows:
Condition
Time, minutes
A.
Test
pressure
180
B.
Atmospheric
pressure
5
C.
Test
pressure
15
D.
Atmospheric
pressure
5
E.
Test
pressure
30
At
no
time during this test shall
the
casing show undue deflection
or
signs
of
weakness
at any
point,
nor
shall
the
external
surfaces
of the
casing show sweating through porous metal
or
leaking through gaskets
or
cracks
or
other defects.
The
Contractor shall
furnish
the
Engineer with
five
certified copies
of the
results
of the
tests.
3.
PERFORMANCE TESTS: Each pump shall
be
subject
to
witnessed performance tests
to
determine
the
head, capacity, speed,
and
brake horsepower
at
each condition point specified
in
paragraph
1.02D.
Tests shall
be
conducted
in
accordance with
the
test code
of the
Standards
of the
Hydraulic Institute except that predicted per-