There’s a wheel barrow in my pipeline!

Rob Welke, from Adelaide, South Australia, took an uncommon phone from an irrigator within the late 1990’s. “Rob”, he mentioned, “I assume 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used to hold equipment for reinstating cement lining during gentle steel cement lined (MSCL) pipeline building in the outdated days.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 happened during 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 plausible excuse for unaccounted friction losses in a brand new 1000mm trunk main!
Rob agreed to help his client out. A 500mm dia. PVC rising primary delivered recycled water from a pumping station to a reservoir 10km away.
The drawback was that, after a yr in operation, there was a few 10% discount in pumping output. The shopper assured me that he had tested the pumps they usually had been OK. Therefore, it just needed 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, where he had extensive 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 strain readings along the pipeline at multiple locations (at least 10 locations) which had been surveyed to offer accurate elevation data. The sum of the pressure studying plus the elevation at every level (termed the Peizometric Height) gave the hydraulic head at each point. Plotting the hydraulic heads with chainage offers a a quantity of point hydraulic gradient (HG), very comparable to in the graph under.
Hydraulic Grade (HG) blue line from the friction checks indicated a consistent gradient, indicating there was no wheel barrow within the pipe. If there was a wheel barrow in the pipe, the HG would be just like the red line, with the wheel barrow between points 3 and four km. Graph: R Welke
Given that the HG was fairly straight, there was clearly no blockage along the finest way, which would be evident by a sudden change in slope of the HG at that time.
So, it was figured that the head loss should be due to a general friction build up within the pipeline. To confirm this principle, it was determined to ‘pig’ the pipeline. This involved utilizing the pumps to drive two foam cylinders, about 5cm bigger than the pipe ID and 70cm long, along the pipe from the pump finish, 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 in need of superb. The system head loss had been virtually completely restored to authentic efficiency, leading to a few 10% circulate improvement from the pump station. So, as a substitute of discovering a wheel barrow, a biofilm was found answerable for pipe friction build-up.
Pipeline performance may be all the time be viewed 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 as a end result of biofilm triggered the pumps not solely to operate at a better head, but that a few of the pumping was pressured into peak electricity tariff. The lowered performance pipeline finally accounted for about 15% extra pumping energy prices.
Not everybody 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) reveals system curve after pigging. Biofilm raised pumping costs by up to 15% in a single yr. 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 equal of a wall roughness of 0.13mm. The identical 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 the same flow! And that’s just within the first year!
Layflat hose can have excessive vitality cost
A living proof was noticed in an vitality efficiency audit carried out by Tallemenco lately on a turf farm in NSW. A 200m lengthy 3” layflat pipe delivering water to a delicate hose increase had a head loss of 26m head in contrast with the manufacturers rating of 14m for a similar flow, and with no kinks within the hose! That’s a whopping 85% enhance in head loss. Not stunning contemplating that this layflat was transporting algae contaminated river water and lay in the hot solar all summer time, breeding these little critters on the pipe inside wall.
Calculated when it comes to power consumption, the layflat hose was liable for 46% of complete pumping power costs through 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 brand new pipe head lack of solely 6m/200m on the similar move, but when that deteriorates as a result of biofilm, headloss could rise to only about 10m/200m as an alternative of 26m/200m, kinks and fittings excluded. That’s a possible 28% saving on pumping power costs*. In terms of absolute vitality 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 have to be trimmed or a VFD fitted to potentiate the energy financial savings. In some cases, the pump may should be changed out for a decrease head pump.
Everyone has a wheel barrow of their pipelines, and it solely will get larger with time. เพรสเชอร์เกจน้ำ can’t eliminate it, but you can control its results, either by way of energy efficient pipeline design in the first place, or attempt ‘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 still joke in regards to the ‘wheel barrow’ within the pipeline when we can’t explain 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 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 wide.
Rob runs common “Pumping System Master Class” ONLINE coaching courses Internationally to pass on his wealth of knowledge he realized from his fifty two years auditing pumping and pipeline techniques throughout Australia.
Rob could be contacted on ph +61 414 492 256, or email . LinkedIn – Robert L Welke