There’s a wheel barrow in my pipeline!

Rob Welke, from Adelaide, South Australia, took an unusual telephone 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 package for reinstating cement lining throughout mild metal cement lined (MSCL) pipeline development within the old 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 through the rehabilitation of the Cobdogla Irrigation Area, near Barmera, South Australia, in 1980’s. It is also suspected that it could simply have been a believable excuse for unaccounted friction losses in a brand 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 year in operation, there was a couple of 10% discount in pumping output. The client assured me that he had examined the pumps and so they were OK. Therefore, it just had to be a ‘wheel barrow’ within the pipe.
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Rob approached this problem much as he had throughout his time in SA Water, the place he had in depth experience locating isolated partial blockages in deteriorated Cast iron Cement Lined (CICL) water provide pipelines through the 1980’s.
Recording hydraulic gradients
He recorded correct pressure readings alongside the pipeline at a quantity of locations (at least 10 locations) which had been surveyed to supply correct elevation data. The sum of the pressure reading plus the elevation at every point (termed the Peizometric Height) gave the hydraulic head at every point. Plotting the hydraulic heads with chainage offers a a quantity of point hydraulic gradient (HG), very comparable to within the graph under.
Hydraulic Grade (HG) blue line from the friction tests indicated a constant gradient, indicating there was no wheel barrow within the pipe. If there was a wheel barrow in the pipe, the HG could be just like the purple line, with the wheel barrow between points three and four km. Graph: R Welke
Given that the HG was pretty straight, there was clearly no blockage alongside the way, which would 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 general friction build up in the pipeline. To verify this principle, it was decided to ‘pig’ the pipeline. This concerned using the pumps to force two foam cylinders, about 5cm bigger 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 efficiency was improved 10% as a result of ‘pigging’. Photo: R Welke
The immediate improvement in the pipeline friction from pigging was nothing in need of amazing. The system head loss had been nearly totally restored to authentic performance, leading to a few 10% circulate improvement from the pump station. So, instead of discovering a wheel barrow, a biofilm was found answerable for pipe friction build-up.
Pipeline performance could be all the time be seen from an vitality efficiency perspective. Below is a graph displaying 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 due to biofilm triggered the pumps not only to function at the next head, however that a number of the pumping was pressured into peak electrical energy tariff. The reduced efficiency pipeline finally accounted for about 15% further pumping power costs.
Not everybody has a 500NB pipeline!
Well, not everybody has a 500mm pipeline of 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) exhibits system curve after pigging. Biofilm raised pumping prices by as much as 15% in a single 12 months. Graph: R Welke
PVC pipe has a Hazen & Williams (H&W) friction worth of about C=155. When lowered to C=140 (10%) through biofilm build-up, the pipe could have the equivalent of a wall roughness of 0.13mm. The similar roughness in an 80mm pipe represents an H&W C worth of 130. That’s a 16% reduction in circulate, or a 32% friction loss improve for the same flow! And เครื่องวัดแรงดันเกจที่นิยมใช้ within the first year!
Layflat hose can have high power value
A case in point was observed in an power efficiency audit performed by Tallemenco lately on a turf farm in NSW. A 200m lengthy 3” layflat pipe delivering water to a gentle hose growth had a head lack of 26m head in contrast with the manufacturers ranking of 14m for the same flow, and with no kinks in the hose! That’s a whopping 85% enhance in head loss. Not stunning considering that this layflat was transporting algae contaminated river water and lay within the hot sun all summer time, breeding those little critters on the pipe inside wall.
Calculated by method of energy consumption, the layflat hose was liable 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 a bigger diameter hose. A 3½” hose has a brand new pipe head loss of only 6m/200m at the identical move, but when that deteriorates due to biofilm, headloss might rise to solely about 10m/200m instead of 26m/200m, kinks and fittings excluded. That’s a potential 28% saving on pumping power costs*. In phrases of absolute power consumption, if pumping 50ML/yr at 30c/kWh, that’s a saving of $950pa, or $10,700 over 10 years.
Note*: The pump impeller would must be trimmed or a VFD fitted to potentiate the vitality savings. In some cases, the pump may have to be changed out for a decrease head pump.
Everyone has a wheel barrow in their pipelines, and it only gets larger with time. You can’t do away with it, however you can management its effects, either via vitality environment friendly pipeline design in 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 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) 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 mostly in Adelaide, South Australia, serving purchasers Australia extensive.
Rob runs common “Pumping System Master Class” ONLINE training programs Internationally to pass on his wealth of data he realized from his 52 years auditing pumping and pipeline methods all through Australia.
Rob can be contacted on ph +61 414 492 256, or e-mail . LinkedIn – Robert L Welke

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