There’s a wheel barrow in my pipeline!

Rob Welke, from Adelaide, South Australia, took an uncommon cellphone 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 delicate metal cement lined (MSCL) pipeline development within the old days. It’s not the primary time Rob had heard of a wheel barrow being left in a large pipeline. Legend has it that it occurred in the course of the rehabilitation of the Cobdogla Irrigation Area, close to Barmera, South Australia, in 1980’s. It can be suspected that it might simply have been a plausible excuse for unaccounted friction losses in a model new 1000mm trunk main!
Rob agreed to assist his shopper 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 about a 10% reduction in pumping output. The consumer assured me that he had tested the pumps and they have been OK. Therefore, it simply needed to be a ‘wheel barrow’ within the pipe.
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Rob approached this problem much as he had throughout his time in SA Water, the place he had extensive experience finding isolated partial blockages in deteriorated Cast iron Cement Lined (CICL) water supply pipelines through the 1980’s.
Recording hydraulic gradients
He recorded correct strain readings alongside the pipeline at multiple locations (at least 10 locations) which had been surveyed to offer correct elevation info. The sum of the stress studying plus the elevation at every level (termed the Peizometric Height) gave the hydraulic head at each level. Plotting the hydraulic heads with chainage offers a multiple point hydraulic gradient (HG), very like in the graph beneath.
Hydraulic Grade (HG) blue line from the friction exams indicated a constant gradient, indicating there was no wheel barrow within the pipe. If there was a wheel barrow within the pipe, the HG can be like the purple line, with the wheel barrow between factors three and four km. Graph: R Welke
Given that the HG was pretty straight, there was clearly no blockage alongside the finest 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 must be due to a general friction construct up in the pipeline. To confirm this principle, it was determined to ‘pig’ the pipeline. This concerned utilizing the pumps to force two foam cylinders, about 5cm larger than the pipe ID and 70cm lengthy, alongside the pipe from the pump end, exiting into the reservoir.
Two foam pigs emerge from the pipeline. The pipeline performance was improved 10% because of ‘pigging’. Photo: R Welke
The instant enchancment in the pipeline friction from pigging was nothing in want of superb. The system head loss had been virtually completely restored to authentic efficiency, leading to about a 10% flow improvement from the pump station. So, as an alternative of finding a wheel barrow, a biofilm was found liable for pipe friction build-up.
Pipeline efficiency may be at all times be viewed from an vitality effectivity 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 increase in system head as a outcome of biofilm triggered the pumps not solely to operate at the next head, but that some of the pumping was compelled into peak electrical energy tariff. The decreased efficiency pipeline in the end accounted for about 15% further pumping energy costs.
Not everybody has a 500NB pipeline!
Well, not everyone has a 500mm pipeline in their irrigation system. So how does that relate to the common irrigator?
A new 500NB
System curve (red line) indicates a biofilm build-up. Black line (broken) exhibits system curve after pigging. Biofilm raised pumping costs by up to 15% in a single yr. เกจวัดความดันน้ำ : R Welke
PVC pipe has a Hazen & Williams (H&W) friction value of about C=155. When reduced to C=140 (10%) through biofilm build-up, the pipe will have the equivalent 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% reduction in circulate, or a 32% friction loss increase for a similar flow! And that’s simply in the first year!
Layflat hose can have excessive power cost
A working example was noticed in an energy effectivity audit conducted by Tallemenco just lately on a turf farm in NSW. A 200m long 3” layflat pipe delivering water to a gentle hose increase had a head loss of 26m head compared with the producers ranking of 14m for the same circulate, and with no kinks in the hose! That’s a whopping 85% enhance in head loss. Not stunning contemplating that this layflat was transporting algae contaminated river water and lay within the hot sun all summer season, breeding these little critters on the pipe inside wall.
Calculated in terms of power consumption, the layflat hose was answerable for 46% of complete pumping energy costs 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 same move, however when that deteriorates as a outcome of biofilm, headloss might rise to only about 10m/200m instead of 26m/200m, kinks and fittings excluded. That’s a potential 28% saving on pumping power costs*. In phrases of absolute power 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 vitality savings. In some cases, the pump might have to be modified 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 get rid of it, but you can management its results, either via energy environment friendly pipeline design in the first place, or strive ‘pigging’ the pipe to eliminate 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 once we can’t clarify a pipeline headloss”, mentioned Rob.
Author Rob Welke has been 52 years in pumping & hydraulics, and by no means sold product in his life! He spent 25 yrs working for SA Water (South Australia) in the late 60’s to 90’s where he carried out intensive pumping and pipeline power effectivity monitoring on its 132,000 kW of pumping and pipelines infrastructure. Rob established Tallemenco Pty Ltd (2003), an Independent Pumping and Hydraulics’ Consultancy primarily based in Adelaide, South Australia, serving shoppers Australia broad.
Rob runs regular “Pumping System Master Class” ONLINE training programs Internationally to move on his wealth of knowledge he realized from his fifty two years auditing pumping and pipeline methods throughout Australia.
Rob can be contacted on ph +61 414 492 256, or email . LinkedIn – Robert L Welke

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