There’s a wheel barrow in my pipeline!

Rob Welke, from Adelaide, South Australia, took an unusual cellphone from an irrigator in the late 1990’s. “Rob”, he mentioned, “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 had been used to hold equipment for reinstating cement lining throughout 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, close to Barmera, South Australia, in 1980’s. It is also suspected that it might just have been a plausible excuse for unaccounted friction losses in a brand new 1000mm trunk main!
Rob agreed to assist 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 few 10% reduction in pumping output. The client assured me that he had examined the pumps and so they have been OK. Therefore, it simply had to be a ‘wheel barrow’ in the pipe.
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Rob approached this drawback much as he had throughout his time in SA Water, where he had intensive expertise locating isolated partial blockages in deteriorated Cast iron Cement Lined (CICL) water provide pipelines through the 1980’s.
Recording เกจวัดco2 recorded correct pressure readings along the pipeline at multiple places (at least 10 locations) which had been surveyed to offer accurate elevation information. The sum of the stress reading plus the elevation at each level (termed the Peizometric Height) gave the hydraulic head at every point. Plotting the hydraulic heads with chainage provides a a quantity of level hydraulic gradient (HG), very related to within the graph beneath.
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 can be just like the pink line, with the wheel barrow between factors three and four km. Graph: R Welke
Given that the HG was fairly straight, there was clearly no blockage along the greatest way, which would be evident by a sudden change in slope of the HG at that point.
So, it was figured that the head loss have to be due to a basic friction construct up in the pipeline. To confirm this concept, it was determined to ‘pig’ the pipeline. This concerned using the pumps to drive two foam cylinders, about 5cm bigger than the pipe ID and 70cm lengthy, 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 improvement within the pipeline friction from pigging was nothing wanting superb. The system head loss had been virtually totally restored to unique performance, resulting in a couple of 10% circulate improvement from the pump station. So, as an alternative of discovering a wheel barrow, a biofilm was discovered liable for pipe friction build-up.
Pipeline performance can be at all times 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 enhance in system head due to biofilm caused the pumps not only to operate at a higher head, however that a variety of the pumping was compelled into peak electricity tariff. The decreased performance pipeline in the end accounted for about 15% further pumping energy prices.
Not everyone has a 500NB pipeline!
Well, not everyone has a 500mm pipeline of 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 costs by as much as 15% in a single year. Graph: R Welke
PVC pipe has a Hazen & Williams (H&W) friction worth of about C=155. When lowered to C=140 (10%) via biofilm build-up, the pipe could have the equal of a wall roughness of zero.13mm. The similar roughness in an 80mm pipe represents an H&W C value of a hundred thirty. That’s a 16% discount in circulate, or a 32% friction loss increase for the same flow! And that’s simply within the first year!
Layflat hose can have high vitality cost
A living proof was noticed in an power efficiency audit performed by Tallemenco just lately on a turf farm in NSW. A 200m lengthy 3” layflat pipe delivering water to a gentle hose increase had a head loss of 26m head compared with the manufacturers score of 14m for the same move, and with no kinks within the hose! That’s a whopping 85% increase in head loss. Not stunning considering that this layflat was transporting algae contaminated river water and lay in the scorching solar all summer, breeding these little critters on the pipe inside wall.
Calculated by way of energy consumption, the layflat hose was responsible for 46% of whole pumping energy costs 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 brand new pipe head lack of only 6m/200m on the similar circulate, however when that deteriorates because of biofilm, headloss might rise to solely about 10m/200m as a substitute of 26m/200m, kinks and fittings excluded. That’s a potential 28% saving on pumping vitality costs*. In terms of absolute vitality 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 must be trimmed or a VFD fitted to potentiate the energy savings. In some instances, the pump could should be changed out for a lower head pump.
Everyone has a wheel barrow of their pipelines, and it only will get greater with time. You can’t do away with it, however you’ll find a way to management its effects, both via vitality efficient pipeline design in 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 concerning the ‘wheel barrow’ within the pipeline once we can’t explain a pipeline headloss”, stated Rob.
Author Rob Welke has been fifty two 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 mostly in Adelaide, South Australia, serving purchasers Australia broad.
Rob runs regular “Pumping System Master Class” ONLINE training programs Internationally to pass on his wealth of information he realized from his fifty two years auditing pumping and pipeline techniques throughout Australia.
Rob may be contacted on ph +61 414 492 256, or e-mail . LinkedIn – Robert L Welke

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