Water Hammer - CA-NV AWWA€¦ · What is Water Hammer? Water hammer events (transient events) are...
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Water Hammer Jake Walsh, P.E. Andy Yang, P.E. October 21, 2014 Tackling Transient Events at San Jose Water Company
Transcript of Water Hammer - CA-NV AWWA€¦ · What is Water Hammer? Water hammer events (transient events) are...
Water Hammer
Jake Walsh, P.E.
Andy Yang, P.E.
October 21, 2014
Tackling Transient Events at San Jose Water Company
Introduction
• [map of SJWC]
Map data © 2014 Google
What is Water Hammer?
Water hammer events (transient events) are disturbances in water flow from one steady-state condition to another.
Introduction
What are Typical Causes of Water Hammer?
– Pump operations– Valve operations– Main breaks– Rapid demand changes (hydrant flow)
(adapted from AWWA Manual M32; Mays, Water Resources Engineering 2005 Edition)
OFF
Wave Propagation Animations
ON
Pump Start Up
Pump Shut Off
Hi
Low
Pressure Scale
ON
OFF
Hydraulic transient related concerns at SJWC:– Infrastructure damage– Property damage– Regulatory compliance– Public safety (pipe ruptures)– Public health (negative pressures)– Complaints
Hydraulic Transient Concerns at SJWC
• SJWC Goals– Verify existence and extent of problem– Determine mitigation measures
• SJWC Approach– Obtain necessary knowledge and analysis tools– Conduct field tests– Analyze data– Select surge protection devices
Transient Analysis – Goals and Approach
Background– History of problems and mitigation efforts– New booster pumps installed with pump control valves– Surge tanks installed
Transient Analysis – Vickery Pump Station
Field Testing
– Select strategic locations to install pressure loggers
• Pump discharge
• High pressure regions
• Low pressure regions
• Dead end mains
– Coordinate with Operations department
• Pump operations
Transient Analysis – Vickery Pump Station
Transient Analysis – Vickery Pump StationTransient Analysis – Vickery Pump StationLogger 1
Pump Discharge
Logger 2Low Pressure Service
Logger 3High Pressure Hydrant
100
110
120
130
140
150
160
170
180
190
200
Pre
ssu
re (
psi
)
Time (s)
Pump Start Up – Pump Control Valve Setting
Transient Analysis – Vickery Pump Station
186 psi
116 psi
Transient Analysis – Vickery Pump Station1
0
10
20
30
40
50
60
70
80
90
100
110
120
130
140
150
Pre
ssu
re (
psi
)
Time (s)
Pump Shut Off – Pump Control Valve Setting
Transient Analysis – Vickery Pump Station
132 psi
11 psi
12 psi
Transient Analysis – Vickery Pump Station1
10 s
0
10
20
30
40
50
60
70
80
90
100
110
120
130
140
150
160
170
180
190
200
Pre
ssu
re (
psi
)
Time (s)
Pump Start Up and Shut Down – Pump Discharge
Transient Analysis – Vickery Pump Station
186 psi
116 psi
Transient Analysis – Vickery Pump StationTransient Analysis – Vickery Pump Station
132 psi
11 psi
1
Transient Analysis – Vickery Pump Station
100
110
120
130
140
150
160
170
180
190
200
Pre
ssu
re (
psi
)
Time (s)
Pump Start Up With Surge Tank - Pump Discharge
186 psi
116 psi
160 psi
Transient Analysis – Vickery Pump Station1
0
10
20
30
40
50
60
70
80
90
100
110
120
130
140
150
Pre
ssu
re (
psi
)
Time (s)
Pump Shut Off With Surge Tank - Pump Discharge
Transient Analysis – Vickery Pump Station
132 psi
11 psi
88 psi
Transient Analysis – Vickery Pump Station1
-20
-10
0
10
20
30
40
50
60
70
80
90
100
110
120
130
140
Pre
ssu
re (
psi
)
Time (s)
Pump Start Up and Shut Down – Low Pressure Service
Transient Analysis – Vickery Pump Station
125 psi
63 psi
Transient Analysis – Vickery Pump StationTransient Analysis – Vickery Pump Station
73 psi
-14.7 psi
2
50
60
70
80
90
100
110
120
130
Pre
ssu
re (
psi
)
Time (s)
Pump Start Up With Surge Tank – Low Pressure Service
Transient Analysis – Vickery Pump Station
125 psi
63 psi
98 psi
Transient Analysis – Vickery Pump Station2
-20
-10
0
10
20
30
40
50
60
70
80
90
Pre
ssu
re (
psi
)
Time (s)
Pump Shut Off With Surge Tank - Low Pressure Service
Transient Analysis – Vickery Pump Station
73 psi
-14.7 psi
38 psi
Transient Analysis – Vickery Pump Station2
120
130
140
150
160
170
180
190
200
210
Pre
ssu
re (
psi
)
Time (s)
Pump Start Up and Shut Down – High Pressure Hydrant
Transient Analysis – Vickery Pump Station
197 psi
Transient Analysis – Vickery Pump StationTransient Analysis – Vickery Pump Station
143 psi
Static Pressure ~ 171 psi Run Pressure ~ 173 psi
3
170
175
180
185
190
195
200
Pre
ssu
re (
psi
)
Time (s)
Pump Start Up With Surge Tank – High Pressure Hydrant
Transient Analysis – Vickery Pump Station
197 psi
Static Pressure 171 psi
188 psi
Transient Analysis – Vickery Pump Station
Record Start Trigger ~ 178 psi
Record Stop Trigger ~ 173 psi
3
120
130
140
150
160
170
180
190
Pre
ssu
re (
psi
)
Time (s)
Pump Shut Off With Surge Tank – High Pressure Hydrant
Transient Analysis – Vickery Pump Station
143 psi
Static Pressure 171 psi With surge tank online, transient waves remained within recording triggers
Transient Analysis – Vickery Pump Station
Upper Record Start Trigger ~ 178 psi
Lower Record Start Trigger ~ 161 psi
3
Background
– History of problems
– Mitigation efforts
Transient Analysis – Pavilion Pump Station
Field Testing
– Strategic locations to install pressure loggers
– Coordination with Operations department
Surge Modeling
– Calibration of existing system
– Future system (with surge protection device)
Transient Analysis – Pavilion Pump Station
Transient Analysis – Pavilion Pump StationTransient Analysis – Vickery Pump StationTransient Analysis – Pavilion Pump Station
LoggerPump Discharge
Reservoir
Transmission Main Split
125
135
145
155
165
175
185
195
205
0 5 10 15 20 25 30 35
Pre
ssu
re (
psi
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Time (s)
Pump Start Up - Pump Discharge
Transient Analysis – Vickery Pump StationTransient Analysis – Pavilion Pump Station201 psi
145 psi
198 psi
Reflection wave from transmission main split
Reflection wave from reservoir
1
2
3
1
2
3
0
20
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60
80
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120
140
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0 5 10 15 20 25 30 35 40
Pre
ssu
re (
psi
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Time (s)
Pump Shut Off - Pump Discharge
Transient Analysis – Vickery Pump StationTransient Analysis – Pavilion Pump Station
156 psi
70 psi
64 psi
200 psi
186 psi186 psi 196 psi
Reflection wave from transmission main split
Reflection wave from reservoir
Initial Surge Tank Sizing:
Transient Analysis – Pavilion Pump Station
𝑻𝒄 =𝟐𝑳
𝒂
𝑺𝒖𝒓𝒈𝒆 𝑻𝒂𝒏𝒌 𝑽𝒐𝒍𝒖𝒎𝒆 = 𝟒. 𝟓 𝒔 × 𝟖. 𝟕 𝒈𝒂𝒍/𝒔 = 𝟒𝟎 𝒈𝒂𝒍
𝑻𝒄 =𝟐 × 𝟒, 𝟎𝟖𝟎 𝒇𝒕
𝟏, 𝟖𝟎𝟎 𝒇𝒕/𝒔= 𝟒. 𝟓 𝒔
𝑺𝒖𝒓𝒈𝒆 𝑻𝒂𝒏𝒌 𝑽𝒐𝒍𝒖𝒎𝒆 = 𝑻𝒄 × 𝑸
125
135
145
155
165
175
185
195
205
0 5 10 15 20 25 30 35
Pre
ssu
re (
psi
)
Time (s)
Pump Start Up - 50% Water / 50% Air
Transient Analysis – Vickery Pump StationTransient Analysis – Pavilion Pump Station201 psi
145 psi
200 psi
40 gal
80 gal
160 gal
265 gal
125
135
145
155
165
175
185
195
205
0 5 10 15 20 25 30 35
Pre
ssu
re (
psi
)
Time (s)
Pump Start Up - 35% Water / 65% Air
Transient Analysis – Vickery Pump StationTransient Analysis – Pavilion Pump Station201 psi
145 psi
200 psi
40 gal80 gal
160 gal
265 gal
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20
40
60
80
100
120
140
160
180
200
220
240
260
0 5 10 15 20 25 30 35 40
Pre
ssu
re (
psi
)
Time (s)
Pump Trip - 2 Pumps 50% Water / 50% Air
Transient Analysis – Vickery Pump StationTransient Analysis – Pavilion Pump Station
236 psi
40 gal
80 gal
160 gal265 gal
15 psi
0
20
40
60
80
100
120
140
160
180
200
220
240
260
0 5 10 15 20 25 30 35 40
Pre
ssu
re (
psi
)
Time (s)
Pump Trip - 2 Pumps 35% Water / 65% Air
Transient Analysis – Vickery Pump StationTransient Analysis – Pavilion Pump Station
236 psi
80 gal
160 gal
265 gal
15 psi
• Hydraulic transients are regularly occurring in water distribution systems
• Transient waves can be far more extreme than anticipated
• Transient waves propagate further than expected
• Certain surge protection devices can be very effective, others not as effective
• Surge protection devices can help mitigate potential public safety and public health concerns
• Surge modeling is highly recommended for sizing surge protection devices
• More transient analysis needs to be performed
Conclusion
Jake Walsh, P.E.
Engineering Unit Manager
Andy Yang, P.E.
Associate Engineer
Contact Information
