There’s a wheel barrow in my pipeline!

Rob Welke, from Adelaide, South Australia, took an unusual cellphone from an irrigator within the late 1990’s. “Rob”, he mentioned, “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 hold kit for reinstating cement lining during mild steel cement lined (MSCL) pipeline building within the previous 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 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 believable excuse for unaccounted friction losses in a model new 1000mm trunk main!
จำหน่ายเกจวัดแรงดัน 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% discount in pumping output. The shopper assured me that he had tested 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 problem much as he had during his time in SA Water, the place he had extensive expertise locating isolated partial blockages in deteriorated Cast iron Cement Lined (CICL) water supply pipelines during the 1980’s.
Recording hydraulic gradients
He recorded accurate pressure readings alongside the pipeline at a quantity of locations (at least 10 locations) which had been surveyed to provide correct elevation data. The sum of the strain reading plus the elevation at each level (termed the Peizometric Height) gave the hydraulic head at each point. Plotting the hydraulic heads with chainage offers a multiple level hydraulic gradient (HG), much like within the graph beneath.
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 within the pipe, the HG could be just like the pink 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 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 should be because of a common friction construct up within the pipeline. To confirm this principle, it was decided to ‘pig’ the pipeline. This involved utilizing the pumps to force two foam cylinders, about 5cm bigger 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. The pipeline efficiency was improved 10% on account of ‘pigging’. Photo: R Welke
The prompt enchancment within the pipeline friction from pigging was nothing in need of amazing. The system head loss had been virtually completely restored to authentic efficiency, leading to a few 10% flow improvement from the pump station. So, as an alternative of discovering a wheel barrow, a biofilm was discovered answerable for pipe friction build-up.
Pipeline performance can be at all times be considered from an energy efficiency 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 enhance in system head because of biofilm brought on the pumps not only to operate at a better head, but that some of the pumping was pressured into peak electricity tariff. The reduced performance pipeline ultimately accounted for about 15% extra pumping power 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) exhibits 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 value of about C=155. When reduced to C=140 (10%) via biofilm build-up, the pipe could have the equivalent of a wall roughness of 0.13mm. The identical roughness in an 80mm pipe represents an H&W C worth of a hundred thirty. That’s a 16% discount in flow, or a 32% friction loss enhance for a similar flow! And that’s simply within the first year!
Layflat hose can have excessive energy cost
A living proof was observed in an power efficiency audit performed 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 lack of 26m head compared with the manufacturers rating of 14m for a similar move, and with no kinks within the hose! That’s a whopping 85% enhance in head loss. Not surprising considering that this layflat was transporting algae contaminated river water and lay within the sizzling sun all summer, breeding those little critters on the pipe inside wall.
Calculated in phrases of power consumption, the layflat hose was liable for 46% of total pumping energy 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 solely 6m/200m on the identical move, but when that deteriorates because of biofilm, headloss might 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 phrases of absolute energy 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 energy savings. In some circumstances, the pump may need to be modified out for a lower head pump.
Everyone has a wheel barrow of their pipelines, and it only will get bigger with time. You can’t get rid of it, but you possibly can control its results, both via vitality efficient pipeline design within the first place, or attempt ‘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’ within the pipeline once we can’t clarify a pipeline headloss”, stated Rob.
Author Rob Welke has been fifty two 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 where 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 primarily based in Adelaide, South Australia, serving shoppers Australia extensive.
Rob runs regular “Pumping System Master Class” ONLINE training programs Internationally to pass on his wealth of knowledge he learned from his 52 years auditing pumping and pipeline methods all through Australia.
Rob could be contacted on ph +61 414 492 256, or email . LinkedIn – Robert L Welke

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