There’s a wheel barrow in my pipeline!

Rob Welke, from Adelaide, South Australia, took an uncommon telephone from an irrigator in the late 1990’s. “Rob”, he said, “I think 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to carry package for reinstating cement lining during gentle metal cement lined (MSCL) pipeline construction in the outdated days.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 big 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 also be suspected that it might just 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 12 months in operation, there was a few 10% reduction in pumping output. The shopper assured me that he had tested the pumps and they were OK. Therefore, it simply needed to be a ‘wheel barrow’ in the pipe.
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Rob approached this problem a lot as he had during his time in SA Water, where he had extensive experience finding isolated partial blockages in deteriorated Cast iron Cement Lined (CICL) water provide pipelines through the 1980’s.
Recording hydraulic gradients
He recorded accurate pressure readings alongside the pipeline at a quantity of places (at least 10 locations) which had been surveyed to provide accurate elevation data. The sum of the stress studying plus the elevation at every level (termed the Peizometric Height) gave the hydraulic head at every point. Plotting the hydraulic heads with chainage provides a a quantity of point hydraulic gradient (HG), very comparable to within the graph under.
Hydraulic Grade (HG) blue line from the friction exams indicated a constant gradient, indicating there was no wheel barrow in the pipe. If there was a wheel barrow in the pipe, the HG could be like the purple line, with the wheel barrow between factors three and 4 km. Graph: R Welke
Given that the HG was pretty straight, there was clearly no blockage along the way in which, which would be evident by a sudden change in slope of the HG at that point.
So, it was figured that the pinnacle loss have to be because of a general friction build up in the pipeline. To affirm this concept, it was decided to ‘pig’ the pipeline. This concerned using the pumps to drive two foam cylinders, about 5cm larger than the pipe ID and 70cm lengthy, along the pipe from the pump end, exiting into the reservoir.
Two foam pigs emerge from the pipeline. เพรสเชอร์เกจลม was improved 10% as a end result of ‘pigging’. Photo: R Welke
The instant enchancment within the pipeline friction from pigging was nothing in need of superb. The system head loss had been virtually totally restored to unique efficiency, resulting in a couple of 10% flow enchancment from the pump station. So, as a substitute of discovering a wheel barrow, a biofilm was discovered liable for pipe friction build-up.
Pipeline performance may be at all times be viewed from an power efficiency perspective. Below is a graph displaying 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 as a end result of biofilm caused the pumps not only to operate at a better head, however that some of the pumping was compelled into peak electrical energy tariff. The reduced performance pipeline ultimately accounted for about 15% extra pumping vitality prices.
Not everyone has a 500NB pipeline!
Well, not everybody 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) shows system curve after pigging. Biofilm raised pumping costs 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 reduced to C=140 (10%) through biofilm build-up, the pipe may have the equal of a wall roughness of zero.13mm. The similar roughness in an 80mm pipe represents an H&W C value of 130. That’s a 16% discount in circulate, or a 32% friction loss enhance for a similar flow! And เกจ์ออกซิเจนsumo within the first year!
Layflat hose can have high energy cost
A living proof was observed in an vitality efficiency audit conducted by Tallemenco just lately on a turf farm in NSW. A 200m lengthy 3” layflat pipe delivering water to a delicate hose boom had a head lack of 26m head in contrast with the producers ranking of 14m for a similar flow, and with no kinks within the hose! That’s a whopping 85% increase in head loss. Not surprising contemplating that this layflat was transporting algae contaminated river water and lay within the hot solar all summer season, breeding these little critters on the pipe inside wall.
Calculated in phrases of energy consumption, the layflat hose was answerable for 46% of total pumping power costs by way of 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 brand new pipe head loss of solely 6m/200m at the identical flow, but when that deteriorates because of biofilm, headloss might rise to solely about 10m/200m as an alternative of 26m/200m, kinks and fittings excluded. That’s a potential 28% saving on pumping vitality costs*. In terms 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 could should be changed out for a lower head pump.
Everyone has a wheel barrow of their pipelines, and it only gets greater with time. You can’t do away with it, but you possibly can management its results, either by way of energy environment friendly pipeline design within the first place, or try ‘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 nonetheless joke concerning the ‘wheel barrow’ within the pipeline when we can’t clarify a pipeline headloss”, mentioned Rob.
Author Rob Welke has been fifty two years in pumping & hydraulics, and by no means sold product in his life! He spent 25 yrs working for SA Water (South Australia) within the late 60’s to 90’s where he conducted intensive 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 primarily based in Adelaide, South Australia, serving purchasers Australia broad.
Rob runs common “Pumping System Master Class” ONLINE training courses Internationally to cross on his wealth of information he discovered from his fifty two years auditing pumping and pipeline methods throughout Australia.
Rob may be contacted on ph +61 414 492 256, or e mail . LinkedIn – Robert L Welke

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