There’s a wheel barrow in my pipeline!

Rob Welke, from Adelaide, South Australia, took an unusual cellphone from an irrigator in the late 1990’s. “Rob”, he mentioned, “I assume 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used to carry kit for reinstating cement lining throughout mild metal cement lined (MSCL) pipeline construction in the outdated days.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 be suspected that it could just 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 primary delivered recycled water from a pumping station to a reservoir 10km away.
The downside was that, after a 12 months in operation, there was a few 10% reduction in pumping output. The consumer assured me that he had tested the pumps they usually have been OK. Therefore, it simply had to be a ‘wheel barrow’ in the pipe.
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Rob approached this downside a lot as he had throughout his time in SA Water, where he had in depth 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 correct pressure readings alongside the pipeline at multiple areas (at least 10 locations) which had been surveyed to supply accurate elevation info. The sum of the pressure studying plus the elevation at every level (termed the Peizometric Height) gave the hydraulic head at each point. Plotting เกจวัดแรงดัน250bar with chainage provides a a quantity of level hydraulic gradient (HG), much like in the graph beneath.
Hydraulic Grade (HG) blue line from the friction checks indicated a constant gradient, indicating there was no wheel barrow in the pipe. If there was a wheel barrow within the pipe, the HG can be just like the pink line, with the wheel barrow between points 3 and four km. Graph: R Welke
Given that the HG was pretty straight, there was clearly no blockage along the finest way, which might be evident by a sudden change in slope of the HG at that point.
So, it was figured that the pinnacle loss should be due to a general friction build up within the pipeline. To verify this theory, it was decided to ‘pig’ the pipeline. This concerned using the pumps to drive two foam cylinders, about 5cm bigger than the pipe ID and 70cm long, alongside 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 end result of ‘pigging’. Photo: R Welke
The prompt enchancment within the pipeline friction from pigging was nothing wanting wonderful. The system head loss had been virtually totally restored to authentic performance, resulting in about a 10% move 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 can be all the time be seen from an vitality efficiency perspective. Below is a graph exhibiting 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 due to biofilm caused the pumps not only to function at the next head, however that a few of the pumping was pressured into peak electrical energy tariff. The reduced performance pipeline in the end accounted for about 15% additional pumping power prices.
Not everyone has a 500NB pipeline!
Well, not everybody has a 500mm pipeline in 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) reveals system curve after pigging. Biofilm raised pumping prices by as a lot as 15% in a single yr. 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 the same flow! And that’s simply in the first year!
Layflat hose can have excessive energy cost
A working example was noticed in an power effectivity audit conducted by Tallemenco recently on a turf farm in NSW. A 200m long 3” layflat pipe delivering water to a gentle hose boom had a head lack of 26m head compared with the manufacturers score of 14m for the same circulate, and with no kinks within the hose! That’s a whopping 85% increase in head loss. Not shocking contemplating that this layflat was transporting algae contaminated river water and lay in the hot solar all summer, breeding these little critters on the pipe inside wall.
Calculated by way of power consumption, the layflat hose was responsible for 46% of whole pumping vitality costs by way of 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 loss of solely 6m/200m at the similar circulate, however when that deteriorates because of biofilm, headloss could rise to only about 10m/200m as an alternative of 26m/200m, kinks and fittings excluded. That’s a potential 28% saving on pumping power costs*. In terms 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 vitality savings. In some instances, the pump might have to be changed out for a lower head pump.
Everyone has a wheel barrow in their pipelines, and it only will get greater with time. You can’t get rid of it, but you probably can management its results, both via vitality efficient pipeline design within 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 about the ‘wheel barrow’ in the pipeline after we can’t explain a pipeline headloss”, mentioned Rob.
Author Rob Welke has been fifty two 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 carried out in depth pumping and pipeline energy 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 purchasers Australia wide.
Rob runs common “Pumping System Master Class” ONLINE training courses Internationally to pass on his wealth of information he realized from his fifty two years auditing pumping and pipeline techniques all through Australia.
Rob may be contacted on ph +61 414 492 256, or email . LinkedIn – Robert L Welke

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