Figure: Schematic of UST lab pipeline facility

The laboratory pipe facility consists of a 145 m long 79 mm-diameter recirculating pipe system. The pipe wall material is made of high-density polyethylene (HDPE). The pipe system is driven by a booster pump and outflows into a reservoir at the other end. The pump is a vertical multistage centrifugal pump KIKAWA KRS 16-3, with 3 impeller and is operated by a Variable Frequency Drive. Alternatively, the flow can be driven by an air-pressure tank using a side connection (Air Tank in above Figure). The air-pressure tank is an Aquasystem model VAV1000 of 2160mm in height and 800mm in diameter. Its maximum working pressure is 10 bar with a pre-charge pressure of 4 bar. The length of pipe system is 131 m for the pressure-tank pipe system setup. The pipeline has large flexibility to accommodate single and multiple leaks, pipe burst simulations, bend effects, discrete and extended blockages, branch connections. Several access measurement locations are available and can be introduced as required. Most importantly, large size high-frequency transducers with increased sensitivity and low self-noise (e.g. Teledyne TC4032 with receiving sensitivity of -170 dB re 1V/μPa and less than 30 dB re 1μPa/sqrt(Hz) noise for frequencies above 2 kHz) can be inserted in the lab pipeline facility. It can also accommodate B&K (Bruel & Kjaer) hydrophones, model 8104 with receiving sensitivity of –205 dB re 1 V/μPa.

The two flow-driving modes produce large variability of noise levels. The standard deviation σ of the flow driven by the air-pressure tank is 0.013 m of pressure head, whereas for pump-driven flow it of the order of 0.20 m head (at 20 Hz pump rotation rate).