There’s a wheel barrow in my pipeline!

Rob Welke, from Adelaide, South Australia, took an uncommon cellphone from an irrigator within the late 1990’s. “Rob”, he stated, “I think 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to carry equipment for reinstating cement lining during mild steel cement lined (MSCL) pipeline development within the outdated days. It’s not the primary 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 is also 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 client out. A 500mm dia. PVC rising major delivered recycled water from a pumping station to a reservoir 10km away.
The downside was that, after a yr in operation, there was about a 10% reduction in pumping output. The shopper assured me that he had tested the pumps they usually have been OK. Therefore, it just 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 intensive experience locating 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 number of areas (at least 10 locations) which had been surveyed to provide accurate elevation info. The sum of the strain studying plus the elevation at each level (termed the Peizometric Height) gave the hydraulic head at every level. Plotting the hydraulic heads with chainage gives a multiple level hydraulic gradient (HG), very like in the graph below.
Hydraulic Grade (HG) blue line from the friction tests indicated a consistent gradient, indicating there was no wheel barrow in the pipe. If there was a wheel barrow in the pipe, the HG would be just like the purple line, with the wheel barrow between factors 3 and 4 km. Graph: R Welke
Given that the HG was fairly 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 should be because of a basic friction construct up within the pipeline. To affirm this concept, it was decided to ‘pig’ the pipeline. This concerned utilizing the pumps to pressure 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 performance was improved 10% on account of ‘pigging’. Photo: R Welke
The immediate enchancment within the pipeline friction from pigging was nothing wanting superb. The system head loss had been almost completely restored to original efficiency, leading to 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 efficiency may be always be considered from an vitality 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 outcome of biofilm brought on the pumps not only to function at a higher head, however that some of the pumping was pressured into peak electrical energy tariff. The decreased performance pipeline ultimately accounted for about 15% further pumping power prices.
Not everyone has a 500NB pipeline!
Well, not everyone has a 500mm pipeline in their irrigation system. So how does that relate to the typical irrigator?
A new 500NB
System curve (red line) signifies a biofilm build-up. Black line (broken) shows system curve after pigging. Biofilm raised pumping prices by as a lot as 15% in a single year. Graph: R Welke
PVC pipe has a Hazen & Williams (H&W) friction value of about C=155. When decreased to C=140 (10%) via biofilm build-up, the pipe could have the equivalent of a wall roughness of zero.13mm. The similar roughness in an 80mm pipe represents an H&W C worth of one hundred thirty. pressure gauge น้ำมัน s a 16% reduction in move, or a 32% friction loss increase for the same flow! And that’s simply within the first year!
Layflat hose can have high energy value
A living proof was noticed in an vitality efficiency audit performed by Tallemenco lately on a turf farm in NSW. A 200m long 3” layflat pipe delivering water to a soft hose growth had a head loss of 26m head in contrast with the producers score of 14m for the same flow, and with no kinks within the hose! That’s a whopping 85% enhance in head loss. Not surprising contemplating that this layflat was transporting algae contaminated river water and lay within the scorching sun all summer season, breeding those little critters on the pipe inside wall.
Calculated by means of power consumption, the layflat hose was liable for 46% of total 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 lack of only 6m/200m on the similar circulate, 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 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 have to be trimmed or a VFD fitted to potentiate the power financial savings. In some circumstances, the pump could need to be changed out for a decrease head pump.
Everyone has a wheel barrow in their pipelines, and it solely will get larger with time. You can’t eliminate it, but you can management its effects, either via energy environment friendly 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 nonetheless joke about the ‘wheel barrow’ within 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 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 extensive pumping and pipeline power 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 broad.
Rob runs common “Pumping System Master Class” ONLINE coaching programs Internationally to pass on his wealth of data he realized from his 52 years auditing pumping and pipeline systems throughout Australia.
Rob could be contacted on ph +61 414 492 256, or e-mail . LinkedIn – Robert L Welke

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