There’s a wheel barrow in my pipeline!

Rob Welke, from Adelaide, South Australia, took an unusual telephone from an irrigator in the late 1990’s. “Rob”, he stated, “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 have been used to hold package for reinstating cement lining during gentle steel cement lined (MSCL) pipeline building within the outdated days.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 happened in the course of the rehabilitation of the Cobdogla Irrigation Area, near Barmera, South Australia, in 1980’s. It can be suspected that it may simply have been a believable 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 drawback was that, after a yr in operation, there was a couple of 10% discount in pumping output. The client assured me that he had examined the pumps and they were OK. Therefore, it just needed to be a ‘wheel barrow’ within the pipe.
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Rob approached this drawback a lot as he had throughout his time in SA Water, where he had extensive 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 stress readings alongside the pipeline at a quantity of areas (at least 10 locations) which had been surveyed to supply correct elevation info. The sum of the strain 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 number of point hydraulic gradient (HG), much like within the graph under.
Hydraulic Grade (HG) blue line from the friction exams indicated a consistent 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 purple line, with the wheel barrow between points three and 4 km. Graph: R Welke
Given that the HG was fairly straight, there was clearly no blockage along the way in which, which might 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 construct up within the pipeline. To affirm this concept, it was determined to ‘pig’ the pipeline. This concerned utilizing the pumps to drive two foam cylinders, about 5cm larger than the pipe ID and 70cm lengthy, alongside the pipe from the pump end, exiting into the reservoir.
Two foam pigs emerge from the pipeline. The pipeline performance was improved 10% because of ‘pigging’. Photo: R Welke
The prompt enchancment within the pipeline friction from pigging was nothing wanting wonderful. The system head loss had been nearly totally restored to authentic efficiency, leading to about a 10% flow improvement from the pump station. So, as a substitute of finding a wheel barrow, a biofilm was found responsible for pipe friction build-up.
Pipeline performance could be always be considered from an vitality effectivity 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 due to biofilm brought on the pumps not solely to function at the next head, however that a number of the pumping was forced into peak electrical energy tariff. The lowered efficiency pipeline ultimately accounted for about 15% additional pumping energy costs.
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) indicates a biofilm build-up. Black line (broken) shows system curve after pigging. Biofilm raised pumping prices by up to 15% in a single year. Graph: R Welke
PVC pipe has a Hazen & Williams (H&W) friction worth of about C=155. When decreased to C=140 (10%) by way of 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% reduction in move, or a 32% friction loss improve for a similar flow! And that’s simply in the first year!
Layflat hose can have excessive energy cost
A working example was noticed in an energy effectivity audit carried out by Tallemenco recently on a turf farm in NSW. A 200m long 3” layflat pipe delivering water to a delicate hose boom had a head loss of 26m head compared with the producers rating of 14m for the same flow, and with no kinks within the hose! That’s a whopping 85% increase in head loss. หลักการทํางานของpressuregauge contemplating that this layflat was transporting algae contaminated river water and lay in the sizzling sun all summer time, breeding these little critters on the pipe inside wall.
Calculated by means of power consumption, the layflat hose was responsible for 46% of total pumping power prices by way of its small diameter with biofilm build-up.
Solution is larger pipe
So, what’s the solution? Move to เกจวัดถังแก๊ส . A 3½” hose has a model new pipe head lack of solely 6m/200m on the identical move, however when that deteriorates as a end result of biofilm, headloss might rise to solely about 10m/200m as a substitute of 26m/200m, kinks and fittings excluded. That’s a possible 28% saving on pumping energy 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 power financial savings. In some circumstances, the pump may need to be changed out for a decrease head pump.
Everyone has a wheel barrow of their pipelines, and it solely gets larger with time. You can’t do away with it, however you can management its effects, either by way of energy environment friendly pipeline design within the first place, or attempt ‘pigging’ the pipe to eliminate 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’ in the pipeline after we can’t explain a pipeline headloss”, mentioned Rob.
Author Rob Welke has been 52 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 where he conducted intensive pumping and pipeline power efficiency 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 clients Australia extensive.
Rob runs regular “Pumping System Master Class” ONLINE training programs Internationally to cross on his wealth of data he learned from his 52 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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