There’s a wheel barrow in my pipeline!

Rob Welke, from Adelaide, South Australia, took an uncommon phone from an irrigator within the late 1990’s. “Rob”, he said, “I suppose there’s a wheel barrow in my pipeline. Can you locate it?”
Robert L Welke, Director, Training Manager and Pumping/Hydraulics Consultant
Wheel barrows had been used to carry kit for reinstating cement lining during mild metal cement lined (MSCL) pipeline construction within the outdated days. It’s not the first time Rob had heard of a wheel barrow being left in a large pipeline. Legend has it that it happened during the rehabilitation of the Cobdogla Irrigation Area, near Barmera, South Australia, in 1980’s. It can additionally be suspected that it might just have been a believable excuse for unaccounted friction losses in a brand new 1000mm trunk main!
Rob agreed to assist his consumer out. A 500mm dia. PVC rising major delivered recycled water from a pumping station to a reservoir 10km away.
The drawback was that, after a year in operation, there was a couple of 10% discount in pumping output. The shopper assured me that he had tested the pumps they usually have been OK. Therefore, it just needed to be a ‘wheel barrow’ within the pipe.
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Rob approached this problem a lot as he had during his time in SA Water, the place he had in depth expertise locating isolated partial blockages in deteriorated Cast iron Cement Lined (CICL) water provide pipelines in the course of the 1980’s.
Recording hydraulic gradients
He recorded correct pressure readings along the pipeline at a number of places (at least 10 locations) which had been surveyed to offer accurate elevation information. The sum of the pressure studying plus the elevation at every level (termed the Peizometric Height) gave the hydraulic head at each point. Plotting the hydraulic heads with chainage gives a multiple point hydraulic gradient (HG), very similar to in the graph below.
Hydraulic Grade (HG) blue line from the friction tests indicated a consistent gradient, indicating there was no wheel barrow within the pipe. If there was เกจวัดแรงกด within the pipe, the HG could be just like the purple line, with the wheel barrow between factors three and four km. Graph: R Welke
Given that the HG was fairly straight, there was clearly no blockage alongside the best way, which might be evident by a sudden change in slope of the HG at that time.
So, it was figured that the head loss should be because of a general friction build up within the pipeline. To affirm this concept, it was determined to ‘pig’ the pipeline. This involved utilizing the pumps to drive two foam cylinders, about 5cm larger than the pipe ID and 70cm long, along the pipe from the pump end, exiting into the reservoir.
Two foam pigs emerge from the pipeline. The pipeline performance was improved 10% as a outcome of ‘pigging’. Photo: R Welke
The immediate improvement in the pipeline friction from pigging was nothing short of amazing. The system head loss had been almost completely restored to unique performance, leading to a couple of 10% flow improvement from the pump station. So, as a substitute of discovering a wheel barrow, a biofilm was found responsible for pipe friction build-up.
Pipeline performance may be all the time be viewed from an energy efficiency perspective. Below is a graph showing the biofilm affected (red line) and restored (black line) system curves for the client’s pipeline, earlier than and after pigging.
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The enhance in system head because of biofilm caused the pumps not solely to operate at a higher head, however that some of the pumping was compelled into peak electrical energy tariff. The lowered efficiency pipeline finally accounted for about 15% additional pumping power prices.
Not everybody has a 500NB pipeline!
Well, not everyone has a 500mm pipeline of their irrigation system. So how does that relate to the average irrigator?
A new 500NB
System curve (red line) signifies a biofilm build-up. Black line (broken) reveals system curve after pigging. Biofilm raised pumping costs by up to 15% in a single 12 months. Graph: R Welke
PVC pipe has a Hazen & Williams (H&W) friction value of about C=155. When lowered to C=140 (10%) by way of biofilm build-up, the pipe could have the equal of a wall roughness of zero.13mm. The same roughness in an 80mm pipe represents an H&W C value of a hundred thirty. That’s a 16% discount in move, or a 32% friction loss improve for the same flow! And that’s simply within the first year!
Layflat hose can have high power cost
A working example was noticed in an vitality efficiency audit performed by Tallemenco recently on a turf farm in NSW. A 200m lengthy 3” layflat pipe delivering water to a soft hose boom had a head loss of 26m head compared with the manufacturers rating of 14m for the same flow, and with no kinks in the hose! That’s a whopping 85% increase in head loss. Not shocking considering that this layflat was transporting algae contaminated river water and lay in the scorching solar all summer time, breeding these little critters on the pipe inside wall.
Calculated by means of vitality consumption, the layflat hose was responsible for 46% of whole pumping vitality prices via its small diameter with biofilm build-up.
Solution is bigger pipe
So, what’s the solution? Move to a larger diameter hose. A 3½” hose has a new pipe head lack of only 6m/200m at the identical move, but when that deteriorates due to biofilm, headloss could rise to solely about 10m/200m instead of 26m/200m, kinks and fittings excluded. That’s a potential 28% saving on pumping vitality costs*. In phrases of absolute vitality consumption, if pumping 50ML/yr at 30c/kWh, that’s a saving of $950pa, or $10,seven-hundred over 10 years.
Note*: The pump impeller would have to be trimmed or a VFD fitted to potentiate the power savings. In some instances, the pump may should be changed out for a decrease head pump.
Everyone has a wheel barrow of their pipelines, and it only will get larger with time. You can’t do away with it, but you can management its results, both via power environment friendly pipeline design within the first place, or strive ‘pigging’ the pipe to get rid of that wheel barrow!!
As for the wheel barrow in Rob’s client’s pipeline, the legend lives on. “He and I nonetheless joke in regards to the ‘wheel barrow’ within the pipeline after we can’t explain a pipeline headloss”, mentioned Rob.
Author Rob Welke has been 52 years in pumping & hydraulics, and never offered product in his life! He spent 25 yrs working for SA Water (South Australia) in the late 60’s to 90’s the place he conducted in depth pumping and pipeline power efficiency monitoring on its 132,000 kW of pumping and pipelines infrastructure. Rob established Tallemenco Pty Ltd (2003), an Independent Pumping and Hydraulics’ Consultancy based in Adelaide, South Australia, serving clients Australia broad.
Rob runs common “Pumping System Master Class” ONLINE coaching programs Internationally to move on his wealth of information he realized from his fifty two years auditing pumping and pipeline methods throughout Australia.
Rob could be contacted on ph +61 414 492 256, or e-mail . LinkedIn – Robert L Welke

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