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Big Al

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I've used ultrasound for many years on bearings and air leaks, but this has been a new application for me.

The site fire system is supplied by one electric pump and two diesel pumps. Pressure drops in the system caused the duty pump to keep switching on. This indicated a leak somewhere on site. By isolating sections of the system, the site services team identified a length of 150 or so metres where they believed the leak should be.

Steel pipe dia 400mm, pressure 8.2bar.

Set ultrasound instrument to 20Hz and max sensitivity and used contact probe on every valve (located in manholes, usually full of water) and every hydrant (at surface). Also listened at intervals at all hard surfaces along the pipe (concrete, tarmac, paving stones). Missed out the sections covered by bare soil. Typically detected at most just a couple of dB. Lifted one manhole cover which was full of water, surface completely calm. As soon as the probe entered the water, 40+dB detected with a continuous whooshing sound. The valve was about 2m deep. Using extension rods managed to get 48dB at the valve. Fitted the airborne sensor as an experiment. It detected 0dB.

Pumped out the manhole and the leak was seen to be coming from a bolted flange.

Apart from the fact that I was called into work on a Saturday, this was quite an interesting job in which to get involved and highlighted the fact that the instruments we use on a daily basis can have many uses.
Walt Strong

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"Set ultrasound instrument to 20Hz" Do you mean 20 kHz?

Walt
Big Al

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Well spotted. 20kHz. Thanks Walt.
Walt Strong

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Good job Al. You were fortunate not to do work here in Boston with temperature near 0-F!

Walt
RustyCas

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Walt, temps here in Arkansas have been in the single digits this week. It’s been brutal running routes at the steel mill with all the wind near the river. I know you’re used to it, but I’m sure not.

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Edwin

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Thanks for sharing. Really a nice application by thinking outside the box. Well done.
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MarkL

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Is that Big River steel Rusty? Seen a video of that plant a while back and it's some place.
Big Al

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I've been watching the weather conditions over there on the news this morning. Looks tough. Here in the UK, the country grinds to a halt after a few inches of snow.

We got lucky with the valve repair. Badly corroded bolts had allowed one of the flanged joints to open slightly. The bolts got replaced in situ and the gasket seems to be intact. For the last 24 hrs it has held pressure ok and the duty pump has stood down.

Prior to the repair, as a further experiment, I tried the airborne unit on the exposed leak after the pit had been pumped out and got 20dB from 2m away.

This highlights a couple of things:

1. The type of leak dictates the most appropriate probe. If this had been leaking into a cavity then the airborne probe might have got a better result than the contact probe, so try all options.

2. How well ultrasound is transmitted through water, but not beyond the surface. I'm now wondering if there are any applications where flooding a localised area and dipping the probe into the water may reveal a result.

OLi

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And you may find a submarine if you are not careful but will not be a Swedish [cool]. Here a sewage pipe leaked beneath a sulfuric acid or similar tank of some size eroding the foundation and the whole thing tumbled over in to a harbor basin..... Not a good day to be a fish or as a submarine you maybe got cleaned.
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Vibe-Rater

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Reply with quote  #10 
Quote:
Originally Posted by RustyCas
Walt, temps here in Arkansas have been in the single digits this week. It’s been brutal running routes at the steel mill with all the wind near the river. I know you’re used to it, but I’m sure not.


Yesterday 42 deg C 107.4 F) pheww.. rgds Melbourne Australia.
MarkL

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-2c here in Tullamore Ireland tonight, we are promised -6 later on (its 8;45 pm at the moment)
OLi

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Reply with quote  #12 
-7C the other day now back to +1 a mild winter so far here. Say speaking about mild, do you have a still around there?:-) Or is T'Dew just a brand?
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MarkL

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Reply with quote  #13 
Wow that is Mild winter for sweðen alright Olov!!!!!


I left my house at 5:30am and was -3 now in County Cork (200k south from my home) and it's -5c.

Yes TULLAMORE Dew whiskey was reborn a few years back and they built a new multi million euro distillery, they are local to me and customer I'm glad to add :-).
The brand is owned by a Scottish whiskey company called William grant.

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