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. “ เกจ์วัดแรงดัน ”, he said, “I assume there’s a wheel barrow in my pipeline. Can you find it?”
Robert L Welke, Director, Training Manager and Pumping/Hydraulics Consultant
Wheel barrows were used to carry equipment for reinstating cement lining throughout gentle steel cement lined (MSCL) pipeline development within the outdated days.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 through the rehabilitation of the Cobdogla Irrigation Area, near Barmera, South Australia, in 1980’s. It can also be suspected that it could simply have been a plausible excuse for unaccounted friction losses in a model new 1000mm trunk main!
Rob agreed to help his shopper out. A 500mm dia. PVC rising major delivered recycled water from a pumping station to a reservoir 10km away.
The problem was that, after a yr in operation, there was about a 10% reduction in pumping output. The consumer assured me that he had examined the pumps they usually were OK. Therefore, it simply needed to be a ‘wheel barrow’ in the pipe.
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Rob approached this problem much as he had during his time in SA Water, where he had extensive 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 stress readings alongside the pipeline at multiple places (at least 10 locations) which had been surveyed to offer correct elevation info. The sum of the strain studying plus the elevation at every point (termed the Peizometric Height) gave the hydraulic head at every level. Plotting the hydraulic heads with chainage offers a multiple point hydraulic gradient (HG), very like within the graph under.
Hydraulic Grade (HG) blue line from the friction tests indicated a constant gradient, indicating there was no wheel barrow within the pipe. If there was a wheel barrow in the pipe, the HG can be just like the purple line, with the wheel barrow between points three and four km. Graph: R Welke
Given that the HG was pretty straight, there was clearly no blockage along the method in which, which might be evident by a sudden change in slope of the HG at that time.
So, it was figured that the top loss have to be because of a basic friction build up in the pipeline. To confirm this theory, it was determined to ‘pig’ the pipeline. This involved using the pumps to force two foam cylinders, about 5cm larger than the pipe ID and 70cm long, along the pipe from the pump finish, exiting into the reservoir.
Two foam pigs emerge from the pipeline. The pipeline efficiency was improved 10% as a outcome of ‘pigging’. Photo: R Welke
The prompt improvement in the pipeline friction from pigging was nothing in need of superb. The system head loss had been almost totally restored to authentic performance, resulting in a few 10% flow improvement from the pump station. So, instead of discovering a wheel barrow, a biofilm was found liable for pipe friction build-up.
Pipeline efficiency may be always be seen from an power efficiency perspective. Below is a graph showing the biofilm affected (red line) and restored (black line) system curves for the client’s pipeline, before and after pigging.
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The increase in system head as a end result of biofilm triggered the pumps not only to function at a higher head, however that some of the pumping was pressured into peak electricity tariff. The decreased efficiency pipeline in the end accounted for about 15% further pumping power costs.
Not everybody has a 500NB pipeline!
Well, not everybody has a 500mm pipeline of their irrigation system. So how does that relate to the typical 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 as much as 15% in a single year. Graph: R Welke
PVC pipe has a Hazen & Williams (H&W) friction worth of about C=155. When reduced to C=140 (10%) via biofilm build-up, the pipe may have the equivalent of a wall roughness of 0.13mm. The identical roughness in an 80mm pipe represents an H&W C worth of 130. That’s a 16% discount in flow, or a 32% friction loss improve for a similar flow! And that’s just within the first year!
Layflat hose can have high vitality cost
A working example was observed in an energy effectivity audit carried out by Tallemenco lately on a turf farm in NSW. A 200m long 3” layflat pipe delivering water to a soft hose increase had a head lack of 26m head in contrast with the producers ranking of 14m for the same circulate, and with no kinks within the hose! That’s a whopping 85% improve in head loss. Not surprising considering that this layflat was transporting algae contaminated river water and lay within the hot sun all summer, breeding these little critters on the pipe inside wall.
Calculated when it comes to energy consumption, the layflat hose was liable for 46% of whole pumping power prices via its small diameter with biofilm build-up.
Solution is larger pipe
So, what’s the solution? Move to a bigger diameter hose. A 3½” hose has a new pipe head loss of only 6m/200m at the similar circulate, however when that deteriorates as a end result of biofilm, headloss may rise to solely about 10m/200m as a substitute of 26m/200m, kinks and fittings excluded. That’s a potential 28% saving on pumping energy costs*. In phrases of absolute energy consumption, if pumping 50ML/yr at 30c/kWh, that’s a saving of $950pa, or $10,700 over 10 years.
Note*: The pump impeller would have to be trimmed or a VFD fitted to potentiate the power financial savings. In some circumstances, the pump might need to be changed out for a lower head pump.
Everyone has a wheel barrow in their pipelines, and it solely will get larger with time. You can’t do away with it, however you presumably can management its results, either by way of energy efficient pipeline design in the first place, or attempt ‘pigging’ the pipe to do away with that wheel barrow!!
As for the wheel barrow in Rob’s client’s pipeline, the legend lives on. “He and I still joke about the ‘wheel barrow’ in the pipeline once we can’t clarify a pipeline headloss”, stated Rob.
Author Rob Welke has been 52 years in pumping & hydraulics, and by no means 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 vitality effectivity 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 shoppers Australia broad.
Rob runs regular “Pumping System Master Class” ONLINE coaching courses Internationally to move on his wealth of data he realized from his 52 years auditing pumping and pipeline methods all through Australia.
Rob could be contacted on ph +61 414 492 256, or e mail . LinkedIn – Robert L Welke

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