There’s a wheel barrow in my pipeline!

Rob Welke, from Adelaide, South Australia, took an uncommon phone from an irrigator in 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 were used to carry equipment for reinstating cement lining throughout delicate metal cement lined (MSCL) pipeline development in the old 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, 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 help his shopper out. A 500mm dia. PVC rising primary delivered recycled water from a pumping station to a reservoir 10km away.
The drawback was that, after a 12 months in operation, there was a few 10% reduction in pumping output. The consumer assured me that he had examined the pumps and so they have been OK. Therefore, it just had to be a ‘wheel barrow’ in the pipe.
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Rob approached this drawback much as he had throughout his time in SA Water, the place he had intensive expertise finding 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 accurate pressure readings along the pipeline at a quantity of areas (at least 10 locations) which had been surveyed to provide accurate elevation information. The sum of the stress reading plus the elevation at each level (termed the Peizometric Height) gave the hydraulic head at each level. Plotting the hydraulic heads with chainage gives a multiple level hydraulic gradient (HG), much like in the graph below.
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 like the purple line, with the wheel barrow between factors 3 and four km. Graph: R Welke
Given that the HG was pretty straight, there was clearly no blockage along the way, which might be evident by a sudden change in slope of the HG at that point.
So, it was figured that the top loss must be as a end result of a common friction construct up in the pipeline. To verify this concept, it was decided to ‘pig’ the pipeline. This involved using the pumps to pressure two foam cylinders, about 5cm bigger than the pipe ID and 70cm lengthy, along the pipe from the pump finish, exiting into the reservoir.
Two foam pigs emerge from the pipeline. The pipeline efficiency was improved 10% on account of ‘pigging’. Photo: R Welke
The immediate enchancment in the pipeline friction from pigging was nothing wanting superb. เกจวัดน้ำยาแอร์refco had been almost completely restored to original performance, leading to a couple of 10% move enchancment from the pump station. So, as an alternative of finding a wheel barrow, a biofilm was found responsible for pipe friction build-up.
Pipeline performance can be always be viewed from an energy effectivity perspective. Below is a graph displaying 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 enhance in system head due to biofilm caused the pumps not only to function at a better head, but that a number of the pumping was pressured into peak electrical energy tariff. The decreased performance pipeline in the end accounted for about 15% extra pumping vitality prices.
Not everybody has a 500NB pipeline!
Well, not everybody has a 500mm pipeline in their irrigation system. So how does that relate to the average irrigator?
A new 500NB
System curve (red line) indicates a biofilm build-up. Black line (broken) shows system curve after pigging. Biofilm raised pumping prices by up to 15% in one yr. Graph: R Welke
PVC pipe has a Hazen & Williams (H&W) friction worth of about C=155. When decreased to C=140 (10%) via biofilm build-up, the pipe could have the equal of a wall roughness of 0.13mm. The similar roughness in an 80mm pipe represents an H&W C value of one hundred thirty. That’s a 16% reduction in flow, or a 32% friction loss enhance for a similar flow! And that’s just in the first year!
Layflat hose can have high vitality cost
A living proof was noticed in an vitality effectivity audit performed by Tallemenco lately on a turf farm in NSW. A 200m lengthy 3” layflat pipe delivering water to a delicate hose increase had a head lack of 26m head in contrast with the producers rating of 14m for a similar move, and with no kinks within the hose! That’s a whopping 85% enhance in head loss. Not stunning considering that this layflat was transporting algae contaminated river water and lay within the scorching solar all summer, breeding these little critters on the pipe inside wall.
Calculated when it comes to vitality consumption, the layflat hose was responsible for 46% of complete pumping vitality costs through its small diameter with biofilm build-up.
Solution is larger pipe
So, what’s the solution? Move to a larger diameter hose. A 3½” hose has a new pipe head lack of solely 6m/200m on the identical flow, but when that deteriorates due to biofilm, headloss may rise to solely about 10m/200m as an alternative of 26m/200m, kinks and fittings excluded. That’s a possible 28% saving on pumping energy 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 need to be trimmed or a VFD fitted to potentiate the vitality financial savings. In some circumstances, the pump might have to be modified out for a lower head pump.
Everyone has a wheel barrow of their pipelines, and it only gets greater with time. You can’t eliminate it, but you’ll have the ability to management its results, both via vitality efficient pipeline design in the first place, or try ‘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 still joke concerning the ‘wheel barrow’ in the pipeline when we can’t clarify a pipeline headloss”, stated Rob.
Author Rob Welke has been 52 years in pumping & hydraulics, and never bought product in his life! He spent 25 yrs working for SA Water (South Australia) within the late 60’s to 90’s the place he carried out in depth pumping and pipeline vitality efficiency 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 purchasers Australia extensive.
Rob runs regular “Pumping System Master Class” ONLINE training programs Internationally to cross on his wealth of knowledge he discovered from his fifty two years auditing pumping and pipeline systems throughout Australia.
Rob may be contacted on ph +61 414 492 256, or email . LinkedIn – Robert L Welke

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