Surge Analysis Services
GENERAL
The purpose of the report is to carry out the preliminary hydraulic and transient analysis of the rising main from One Stage to Second Stage
The scope of analysis is limited to provide the Transient analysis Graphs for the single pipeline system.
OBJECTIVES
To construct a mathematical model of the pipeline system using the supplied data and drawings
To check the steady state conditions within the system
To check the magnitude of the positive and negative surge pressures generated as a result of total power failure at the pumping station under peak flow conditions without presence of any surge protection device
To check the magnitude of the positive and negative surge pressures generated as a result of total power failure at the pumping station under peak flow conditions, When Surge control device as per supplied data is placed in system.
ANALYSIS METHODOLOGY
The study of the proposed water pumping scheme from Pump House to Discharge Point has been carried out by constructing software based mathematical model of the system. In this study, the effect of steady and transient operation of pumping on the system has been included.
This model considered the suction conditions, pumps, transfer main and discharge conditions etc. Stimulations were then carried out in which total power failure occurred at the pumping station. The calculations of changes in pressure and flow rate throughout the simulations are based on the well-established Wave Plan Method.
AVAILABLE SOFTWARE
KY PIPE 2014
SAP 2 Developed By IISc. Bengaluru
SAMPLE GRAPHS
Bladder Vessel
GENERAL
The Bladder Vessel serves as an important component of combined surge protection systems protecting against both positive and negative pressure surges. The tank’s internal compressible bladder separates the fluid from air that is pre-compressed between the metal tank housing or in the bladder.
A Bladder Surge Vessel is a surge control device installed with a butyl rubber bladder with Nylon Fabric reinforced in it for Better Life and Extra Strength. A pre-charge pressure is calculated with the help of Surge analysis software to give the required pressure to push the water into the system when the pump trip. As there is no contact between the compressed air and the water, there is no dissolution. Thus, there is no requirement for a permanent regulation system including compressors, etc.
Once the vessel has been commissioned and the correct pre-charge has been introduced, the vessel will operate automatically, emptying when called upon and refilling with the return waves until naturally reaching its steady state balance.
TYPES OF BLADDER VESSEL SYSTEM
MOC Of VESSEL
SA 516 Gr.60/70
IS 2062 E-250
As per client Req.
ADVANTAGES BLADDER VESSEL TYPE SURGE PROTECTION SYSTEM
- Maintenance Cost in minimum
- “0” Chance of human error in Operational Condition
- Running Cost is very low
- “0” Instrument piping; Self Controlled.
- Reduced size and foundation cost
- No Civil Structure for compressor/Air Receiver Tank
- 100 % Reliability
- Very Simple installation. Almost Plug and play.
DISADVANTAGES BLADDER VESSEL TYPE SURGE PROTECTION SYSTEM
- Difficulty in assessing the Volume of Air
- Chances of Bladder Failure due to wrong commissioning & improper Installation.
Compressor Type Surge Tanks
GENERAL
Compressor type Surge Tank is formally Known as Air Vessel based surge Protection system .Air Vessel Systems is proven technology and It’s Been used from last 50 years .Air Vessel based surge protection systems are one of the most effective systems for controlling the surge waves in the cross-country rising mains and lift irrigation projects During the Pump Failure.The Air Vessel system is offered along with the Air Compressor, Air Receiver, Level Indicator, Level Sensors, PRV, Connecting Pipe, Pneumatic piping, Davit arm assembly, Ladders and control panel and other accessories required for System. Air vessels are proposed on both vertical and Horizontal Mountings
MOC Of VESSEL
SA 516 Gr.60/70
IS 2062 E-250
As per client Req.
ADVANTAGES OF COMPRESSOR TYPE /AIR VESSEL TYPE SURGE PROTECTION SYSTEM
- Proven System and Adopted in Various Government Department by last 50 Years
- Visually Supervise the System
- Operate manually as well as Automatically
- Air- water ratio is supervise easily
DISADVANTAGES OF COMPRESSOR TYPE /AIR VESSEL TYPE SURGE PROTECTION SYSTEM
- Fully Dependent on Power
- Heavy Running and Maintenance Cost Due to Combination Of Mechanical and Automation System
- Operator required for Operation and Supervision
- Dependent on Compressed Air
- Civil Cost is High Due to Extra Foundation is required for Compressor, Air receiver and Compressor Room.
Two Way Surge Tank
GENERAL
Two way surge tank is one of the Surge Protection system used in Maharashtra for controlling the surge waves in the cross-country rising mains and lift irrigation projects During the Pump Failure with using of atmospheric air. The volume of water in the two way surge tank is calculated as per theStephenson’s formula. This volume also knows asWater quantity to be discharge in the pipeline when the negative pressure is created in the pipeline and this water quantity will be used for avoiding the vacuum condition in the pipeline During the Pump Failure .Two way surge tank is fully mechanical system and depends on its allied accessories like Air Valves, Non Return Valves, isolation Valves. Two Way surge tank is generally used with Air vessel/Bladder vessel and where maximum chances of developing the negative pressure.
MOC Of TANKS
SA 516 Gr.60/70
IS 2062 E-250
As per client Req.
ADVANTAGES OF TWO WAY SURGE TANKS TYPE SURGE PROTECTION SYSTEM
- Self-Standing and No Instruments required for operation and Control, Fully Mechanical System
- Operates on Atmospheric Air in Surge Condition
- “0” Rs. Running Cost
- “0” Power Requirement
- Very Simple installation
- No Civil Structure for compressor/Air Receiver Tank
DISADVANTAGES OF TWO WAY SURGE TANKS TYPE SURGE PROTECTION SYSTEM
- Volumes of Tank becomes almost double than Other Two Systems. (Workout By Stephenson’s formula )
- Due to Large Volume , Costing of this System is Higher than Bladder Vessel type Surge Protection System and Equal as Conventional Type / Air Vessel Type Surge Protection System
- Fully Dependent on Air Valves and Non Return Valves provided for Air inlet to avoid vacuum condition in Tank
- Bottom connection line is critical to erect and Costlier than other two system
Surge Shaft
GENERAL
Surge shaft is provided in water conductor systems to radically reduce the pressure surges due to water hammer and to prevent excessive internal loads on the pressurized Pipeline
Surge shaft is a structure provided at the end of headrace tunnel or pipe to account for water hammering effect in the pipe at its downstream. Surge shaft is considered to be an important component of Hydropower projects, especially for those involving headrace pressure tunnels.
In most of the hydropower projects involving pressure tunnels when power house is suddenly shut down by closing the turbine valves the water in penstock stops suddenly and because of the inertia of incoming water from the back creates a resonance effect, which in a mean while causes water hammering effect. If no arrangement has been made to prevent this water hamming it may result in bursting of penstock pipe and may lead to serious stability issues of the hydropower project, the best solution is to provide a surge shat or surge tank depending upon the site constraints.
MOC Of TANKS
IS 2062 E-250
RCC
Conversion of Conventional Surge System into Bladder type Surge Protection System
GENERAL
Ongoing through various methods it was found that a “bladder vessel technology” is most effective in the present scenario. However the technology has to be implemented utilizing the present major component like, the main surge tanks. This is mainly stressed, as the tanks have given perfect protection to the system for the past over 25 years. (From the day of their inception in the system). The new technology has one major change i.e. is self-sustaining and has zero dependency on any instrumentation. This gives its prime importance in selection. As explained in the conventional system, the ratio of water to the air column in the tank has to be almost equal. i.e. if water of 85 CUM at pressure X is to be the tank, then compensating 85 CUM at same pressure X has to be there in the tank. Considering tank volume to be 170 CUM and system pressure as X. In the conventional system this air column is maintained by using compressors and instrumentation controls. In the up gradation of technology, the column of air will be maintained by keeping it entrapped in a large balloon. This balloon will be made of rubber / polymer material with suitable reinforcement. This material will be such that it will have almost zero permeability of leakage of air through the membrane or its welded points. This feature makes it unique equipment. This impermeability of leakage makes a perfect separation between the pressurized air and water. This makes the solvency of air “zero”.
As the new system does not allow any air to get dissolved in the water, this avoids the refilling of air. And as the system does not call for any air filling, it eliminates the compressors requirement along with all accessories and instrumentation. Hence the new technology calls for
The main surge tank with complete cleaning from inside.
A properly sized and shaped bladder made from flexible material which can withstand pressure of system and it variations.
If required as an additional safety, a pressure transmitter can be fitted on tank to communicate the health of the tank to control room.
METHODOLOGY
The job is to Install the Rubber Bladder inside existing surge vessel and convert it into bladder vessel. We have to do this activity on site itself.
- ISOLATION OF VESSELS
- CLEANING OF VESSELS
- MINOR FABRICATION IN VESSEL
- SANDBLASTING IF POSSIBLE
- PAINTING OF VESSEL
- BLADDER INSERTION IN VESSEL
- PRECHARGE and COMMISSIONING SYSTEM
Zero velocity Valve
GENERAL
ZeroVelocityValveis the type of Surge protection device used in Cross county Water supply pipelines and Irrigation Pipelines. It consistsofaspringloadedclosingdiscforstoppingreverse flowincaseoffailureofpumps,enclosedinanoutershell.Awelldesigneddomeis locatedinbackofdisctostreamlinetheflowinroutineoperation.Discismounted onacentralshaftandisfurthersupportedbyguiderods.Valveisprovidedwitha byepassarrangementValvesaregenerallysuppliedwithbarrelendsbutcanalsobeflanged,ifsodesired. Thespringsaredesignedinsuchamannerthatthevalveremainsfullopenwhen25% ofdesignedvelocityisachieved.Incaseofclosureofpump,discstartsclosingin relationtodecreaseofvelocityandfullycloseswhenvelocitydropsneartozero. Thusupstreamwatercolumnispreventedfromcreatingwaterhammer wave. Byepassarrangementkeepspressurebalanceonbothsidesofdisc.Italsoprevents Creationofvacuumindownstream side. Theprincipalbehindthedesignofthisvalveistoarresttheforwardmovingwatercolumn atzeromovementi.e.whenitsvelocityiszeroandbeforeanyreturnvelocityisestablished,thevalvefittedinapipelineconsistsofanoutershellandoninnerfixeddomeleavinga streamlinedannularpassageforwater. Aclosingdiscismountedoncenterandaperipheralguidebarisheldatthecloseposition bycompressedspringswhenthereisnoflowofwater.Oneormultinos.(Dependsupon thesizeofvalve)bypassarrangement(notlessthan10Rofnominalborearea)connects theupstreamanddownstreamsideofdisc.
The main advantages of ZERO VELOCITY VALVES are
The job is to Install the Rubber Bladder inside existing surge vessel and convert it into bladder vessel. We have to do this activity on site itself.
- Controlled closing characteristics
- Low head loss due to streamlined design.
OBJECTIVES OF ZERO VELOCITY VALVE
Zero velocity valves are developed to eliminate water hammer problems. In common practices swing check valves are installed on the pump discharged end. Theoretically, swing check valve close quickly when the pump is shut off but actually not quick enough to prevent reversal velocity of flow. The flap of the swing check valves will slam against its body seat and will cause noise Vibration pipe stressing and seat damaging.
Zero velocity valves has function to problem or limiting water surge after power failure. Locations of the valves have therefore to be based on the results of the analysis of water column separation.Zero velocity valves are so placed that the entire length of water column is suitably dividedin spite of different gradients and undulations. More than one valve may be required in such casesZero velocity con be mounted in any position i.e. horizontal, vertical or inclined pumpingmain as well as gravity main, due to the center guided spring assisted design. This eliminates the problems arising installing a valve WRONG orientation or necessity of changing existing lines to accommodate the valves design. Inventory requirement ore reduced because one valve design con be used in a wide variety of application, regardless of the valve’sin the line (when the valve is used vertical download flow position, a heavier spring is simply substituted to compensate for the weight of the disc and shaft.
| Size Range | 100mm to 2000mm |
| Design | Mfr’s Std. |
| Make | Jupiter |
| Type To Valve | Water hammer control spring loaded surge protection check valve |
| Pressure Rating | PN 10 /PN 16 / PN 20 & PN 25 |
| END Connection | Barrel End/ Extended Barrel End/ Flanged End |
| Barrel, Disc & Others M. S. Parts | M.S. to IS: 2062 Gr. Fe-410-W |
| Seating | S.S. to AISI – 304/316 or S.S. Overlay |
| Disc Seal | EPDM/Nitrile/Natural/Synthetic Rubber |
| Spring | Spring Steel |
| By-Pass Arrangement | Keep pressure balance on both side of disc. It also prevents creation of vacuum in downstream side. |
| Application | Resist the back flow of the water column during pump trip or closure, thus preventing the positive surge by reducing the energy of the water hammer |
| Special Features |
|
Surge suppression valves 3 stage Air Cushion Valves
GENERAL
Air valves are an important tool for surge dampening and suppression. Accurateair valve specification, location and sizing are vitally essential for effective,efficient liquid flow and for sufficient pressure surge dampening and Suppression. In this paper and presentation I will describe the air valves thatwere designed for surge protection, explain their operation, and list ways andtools to specify, to locate, and to size them for maximum flow Efficiency andsurge protection.
Air valves are the most efficient and most cost effective tools for air control inpressurized liquid conveyance systems.Air valves in general are often misnamed as “Air release valves” or, lessfrequently, as “Vacuum breakers”. Actually, there are three basic types of airvalves that function differently and serve different objectives. The Large Orifice Air Valve is usually called a “Kinetic Air Valve” in Europeand other parts of the world, and an “Air/Vacuum Valve” in the United Statesand North America. This type of air valve discharges large quantities of air fromthe pipeline at pipe filling and admits large quantities of air at pipe drainage(planned or due to rupture) or at water column separation. This air valve closeswhen the pipe fills up with liquid, and does not reopen until pressure within theair valve (pipeline) drops below atmospheric pressure.
The Small Orifice Air Valve is usually called an “Automatic Air Valve” inEurope and other parts of the world, and an “Air Release Valve” in the UnitedStates and North America. This air valve continues to release small quantities ofair when the system is pressurized and the Large Orifice Air Valves do notfunction.
The Double Orifice or Combination Air Valve, includes two components, and performs the functions of the two types of air valves above.Within the three categories of air valve types above, there are a variety of different models with a variety of additional accessories and attributes. One ofthe most important recent enhancements in air valve design is the non-slam,surge suppressing air valve.
Down-surges can cause damages to pipe fittings and accessories or can generatesuction of gaskets, of seals, of dirt, of chemicals, of pollutants, etc’, into thepipeline. When the pipeline is uniformly weak round its circumference, severedown-surges can result in pipe implosion and collapse. When certain areasaround the circumference of the pipe are weaker than others, such as the pipe’scrown, recurring incidents of cyclic down-surges and up-surges can result inpipe ruptures and bursts.
The use of air valves as vacuum breakers for the prevention of vacuumconditions and consequent pipe collapse is well known and recognized worldwide.Their potential contribution to the control of cyclic pressure surges,Brought on by the water column separation process, is less known, andsometimes challenged. In his presentation at the Fourth International Meeting on Water ColumnSeparation in Cagliari, Italy, on September 11-13, 1979, C. Samuel Martin, from The School of Civil Engineering of the Georgia Institute of Technology in Atlanta,concluded that: “Column-separation induced water hammer can be eliminatedby vacuum breakers of adequate size”. Since pressure surges, brought on by water column separation are cyclic, control of one extreme of the pressure wave, say the down-surge, and has a definite effect onthe opposite extreme, in this case, the up-surge. The advantages of air valves, inrestraining up-surges by controlling down-surges, is becoming more and morerecognized. Advances in digital computation and better understanding oftransient flow and surge processes, brought to the development of mathematicaland digital models that are able to analyze and predict transient processes, whiletesting possible solutions.
TYPES OF AIR VALVES
AIR RELEASE VALVES
VACCUME BREAKER VALVE
KINETIC AIIR VALVES
TWO STGAE COMBINATION AIR VALVE
THREE STAGE COMBINATION AIR VALVE