Innovative technologies for leak detection in pressure pipe systems (Optimal test conditions for leak detection by means of transients)

Transcription

1 Conferenze sulle Strategie di Gestione delle Perdite Idriche IWA Water Loss Task Force Visit Italy (Optimal test conditions for leak detection by means of transients) B. Brunone, M. Ferrante, S. Meniconi and C. Almadori Università degli Studi di Perugia Dipartimento di Ingegneria Civile ed Ambientale

2 OUTLINES Transient test approach for leak detection Description of a portable pressure wave-maker for leak detection and pipe survey (B.U.A.T.T.A.) Numerical model Model verification Leak detection and pipe survey by means of B.U.A.T.T.A.

3 ansient test approach r leak detection intact pipe d = 1.49 cm d = 0.99 cm damaged pipe R L x l = m X = m; D = 93.3 mm V IWA Water Loss Task Force Visit Italy

4 Problems related to transient test analysis 1) The limited availability of valves that generate fast transients, particularly in large diameter pipes 2) The difficulty of finding valves in sections where measurement points can be set up 3) The challenge of generating safe transients 4) The quality of the pressure signal to be analyzed

5 Description of B.U.A.T.T.A. (Basic United Apparatus for Transient Test Analysis)

6 Description of B.U.A.T.T.A. (Basic United Apparatus for Transient Test Analysis)

7

8 40.4 m m 22.3 m B = B.U.A.T.T.A device R= Upstream Reservoir m = section immediately upstream from the connection flange i = section 255 m upstream from the connection flange Air volume in B.U.A.T.T.A. U B t = 0 s = 0.02 m 3

9 = 0.18 m

10 Numerical model ) Boundary condition corresponding to the B.U.A.T.T.A the continuity equation for the device the state equation for air in the vessel du B = Q dt hu = B n B 1 costant an orifice equation that relates Q 1 to the hydraulic characteristics of the control valve ( ) Q = C A 2g h h 1 v v B 1 the compatibility equation valid along the negative characteristic gdh 1 dq J adt + Adt + = 0

11 Numerical model ) Boundary condition corresponding to the upstream servoir he constancy of supply reservoir level he compatibility equation valid along the positive characteristic h R = costant gdh 1 dq + + J = 0 adt Adt ) Internal nodes the compatibility equation valid along the negative characteristic the compatibility equation valid along the positive characteristic IWA Water Loss Task Force Visit Italy gdh 1 dq J adt + Adt + = gdh 1 dq + + J = adt Adt

12 Parameters h1, T h1, the discrepancy in the pressure signal δ = h h Θ Bs, 1, s 100 Τ Θ IWA Water Loss Task Force Visit Italy

13 Parameters the discrepancy in the pressure signal δ = h h h 1, T 1, Θ h Bs, 1, s 100 the volumetric percentage of air initially presented in the vessel u = U W Bs, B 100 the degree of throttling of the control valve ζ = CA v A v 100

14 ζ = 0.25% u = 10% δ = 11%

15 Results of the numerical analysis

16 Model verification u = 24 % ζ = 0.25 % δ = 0.3 %

17 δ = 0.03 % Model verification u = 35 % ζ = 0.13 %

18 ak detection and pipe survey by means of B.U.A.T.T.A u = 35 % ζ = 0.13 % ε = 0.37 % d = 0.99 cm L x l = m V

19 B IWA Water Loss Task Force Visit Italy ak detection and pipe survey by means of B.U.A.T.T.A

20 Problems related to transient test analysis )The limited availability of valves that generate fast transients, particularly in large diameter pipes )The difficulty of finding valves in sections where measurement points can be set up )The challenge of generating safe transients )The quality of pressure signal to be analyzed When using B.U.A.T.T.A. 1) The moderate size of connection valve allows for fast and easy manoeuvres 2) The device is portable and ca be easily connected at any section 3) The amplitude of the pressure wave can be fixed exactly 4) A good quality of pressure signal can be obtained

21 CONCLUSIONS 1. A portable device producing pressure waves of a given amplitude is explained and illustrated. 2. Such an appliance can easily be carried to plants and facilities and used within a leak detection and survey campaign based on the execution of transient tests. 3. In the first part, the performance of a model fine-tune for the definition of optimal test conditions is showcased, while in the second part, these results are verified with laboratory tests carried out at the Water Engineering Laboratory of the University of Perugia. 4. Results of experimental tests show the possibility of detecting anomalies present in a pipe system also producing pressure waves of limited amplitude (i.e., few meters of water column).

22 Università degli Studi di Perugia Dipartimento di Ingegneria Civile ed Ambientale astea s.p.a Osimo (AN) CORSI DI FORMAZIONE PROFESSIONALE 2006 n. 20 Corso Gestione e monitoraggio dei campi-pozzi settembre 2006 Perugia