session e - e6 - first ten years of practical experiences

CIB W062 Symposium 2005

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First ten years of practical experiences with use of water hydraulics diode for elimination of water hammer E. Petrešin(1), M. Nekrep Perc(2) (1) [email protected] (2) [email protected] (1) Faculty for Civil Engineering, University of Maribor (2) Faculty for Civil Engineering, University of Maribor

Abstract In our work we are explaining experiences, advantages and problems in using water hammer damper is water hammer prevention element in water distribution systems in last ten years. The results are testifying that water hammer damper is one of the most efficient instruments for prevention against water hammer. In addition we are presenting suggestion for solving problems with noise and water hammer in high-rise buildings drainage systems with use of water hammer damper named also water hammer damper.

Keywords High-rise buildings, drainage, water hammer damper

1. Preface Water hammer damper prevents water distribution systems again water hammer and another types of oscillations. With significant reductions of oscillations we eliminate damage on tube systems, pump stations, etc. Water hammer damper is also equipped with recurring flap and vacuum and pressure valve, which is also used as safety valve. In case of horizontal pumps water hammer damper is mounted directly on pump. The size of pump defines the size of hydraulics diode. In case submersible pumps water hammer damper is mounted in utility building over the well. It acts considerable faster then the pressure boiler. The volume of water hammer damper is about 50 times smaller than the volume of appreciate pressure boiler.


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Figure1 - Solution with pressure boilers (Pump station Tuzla BiH)

Figure2 – New solution with water hammer damper (Pump station Tuzla BiH)

Comparison table water hammer damper versus pressure boiler

- Advantageous effect on quality of water (there is no water stagnation) - Easier and cheaper technical documentation - Much cheaper (works without pressure station )

- Mechanical device (works without electrical energy) - Easy mounting on pump

- Low operation and maintain cost - Change of working pressure or water flow doesn’t require change of

hydraulics diode - Minimal energy loses in the unit


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2. Dangerous phenomena caused by water hammer Occurrence of vacuum in pipe lines is caused by:

- pumps breakdown - uncontrolled valve closing - pipeline breakdown - by mistake of control stuff - etc

Figure 3 - Damage caused by water hammer; pump station in Italy

If pressure remains higher than atmospherically pressure such an unpredictable events doesn’t cause any damage.


In case of vacuum in the pipe line, outside pressure pipe line could not resist such a pressure difference, water column could be broken and when it is again established pipe lines could be damaged.

In most cases pipa lines are not damaged immediately, but materials are under repeated stress and became fatigued. Pipe lines are flattened and become untied during the time.


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Water could be polluted and we have higher water loses. Cavitation causes pipe lines damages. Also the momentary rise of pressure causes damage in the pipe lines and joints. 3. Discussion about water hammer prevention methods In water distribution system we have to take measures against water hammer. Measures are needed all kind of water distribution systems. For prevention against too low or too high pressure in pipe lines following measurements are used:

- longer time of closing valves

- over dimensioning of pipe line

- deformable sections of pipe line

- oval section tube

- parallel pipe lines

- air valves

- “by pass”

- hydraulics diode

5. Description of water hammer damper Water hammer damper prevents water distribution systems again water hammer and another types of oscillations. Water hammer damper is also equipped with recurring flap and vacuum and pressure valve, which is also used as safety valve.


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Figure 6 – Water hammer damper prepared for transportation

In case of horizontal pumps water hammer damper is mounted directly on pump. The size of pump defines the size of hydraulics diode. In case submersible pumps water hammer damper is mounted in utility building over the well. Main characteristic of water hammer damper unit is that it is completely mechanical unit consequently it doesn’t need any energy source to be functional. It uses only its unique shape to reduce velocity of fluid.

Figure 7 – Recurring flap

It acts fast and need less volume than other common solutions. Also building for pump station is reduced considerable. Quality of water is improved due absence of water stagnation. Pressure losses are negligible. It works under low operation and maintain cost. Technical documentation for build in is easy and low cost.

6. Practical applications of water hammer damper during past ten years We have many successful application of hydraulic diode in water distribution systems in our country and abroad. There are forty eight pump stations in Slovenia, Croatia, Sweden, Serbia and Montenegro and Bosnia and Herzegovina equipped with water hammer damper.


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Figure 8 – Application in the Pump station Ptuj We have chosen pump station in our neighborhood which could be easily controlled and in case of any problems we are able to act immediately.

Figure 9 – Small pump station building is needed


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Figure 10 – Fluctuation pressure


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Figure 11 – Pressure cauldron without and with hydraulic hammer damper

After ten years of experiences we could say that the new solution for water hammer prevention is here.


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7. Suggestion for solving problems with noise and water hammer in high-rise buildings drainage systems with use of hydraulics diode Water hammer damper with its speed reduction capabilities and other qualities (low cost and complete mechanical unit) is very unique and suitable solution as noise and water hammer effect reduction element in high rise buildings. Our solution forced waste water to helical flow near the pipe wall. In the center we have free air flow. It enables the easiest possible transition from horizontal to the vertical flow.

Figure 11 - High-rise buildings drainage systems with our solution


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8. Conclusion In past ten years water hammer damper proved itself as very useful solution for prevention against water hammer with many qualities. The results are testifying that water hammer damper is one of the most efficient instrument for prevention against water hammer. In addition we propose the use of water hammer damper as a noise and water hammer prevention in the high-rise buildings drainage. We propose detailed analyses and measurements in the experimental high rise buildings.

9. References 1. Zobel, R: Versuche an der hydraulischen Rueckstromdrossel (Mitteilungen des

Hidraulischen Institutes der TH Muenchen 1936) 2. Roberts, P.J., Syred, N., Sidna, B.S.: A new design of a thin Chamber Vortex Diod

and its Application to Fluidic Pumping Systems involving Near Boiling Liquids (Report No. 308, Aug. 1976, University of Wales)

3. Hartl, J.: Zur Hydromechanik des Drallschachtes; Oesterreichische Wasserwirtschaft, Jahrgang 35 (1983), Heft 9/10

4. Pemic, A., Petrešin, E.; Raziskave krožnih diod (VGI Ljubljana, 1991) 5. Petrešin, E.: Analysis of Existing Analytic Expressions for the Roughness

Coefficients witha a Proposal for their Omprovment Concerning Aplication in Water Supply Network: Acta hydrotechnica No.4, Ljubljana, dec 1987

6. Kryzk, M., Pemic. A.: Application of Vortex Diode in Pressuriezed Hydrotehnical Systems; 1st Croatian Conference of Water, 2 Proccedings Dubrovnik, Maj 1995, pp. 369-376

7. Petrešin, E: Druckpulsationdaempfer; Offenlagerungsschrift, BRD – Deutsches Patentamt, 1994

8. Petrešin Eugen: Urbana hidravlika, Ljubljana 1997 9. Wylie E. B. & W. L. Streeter: Fluid Transients McGraw - Hill, 1978


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10. Presentation of Authors Dr. Eugen Petrešin is Professor at Faculty for Civil Engineering, University of Maribor and Head of The chair for hydraulics. Matjaž Nekrep Perc is Teaching Assistant at Faculty for Civil Engineering and postgraduate student of Informatics sciences

session e - e6 - first ten years of practical experiences

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