There’s a wheel barrow in my pipeline!

Rob Welke, from Adelaide, South Australia, took an unusual cellphone from an irrigator within the late 1990’s. “Rob”, he said, “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 have been used to carry kit for reinstating cement lining during gentle metal cement lined (MSCL) pipeline building in the outdated days.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 occurred in the course of the rehabilitation of the Cobdogla Irrigation Area, near Barmera, South Australia, in 1980’s. It can be suspected that it could simply have been a believable excuse for unaccounted friction losses in a model new 1000mm trunk main!
Rob agreed to assist his consumer out. A 500mm dia. PVC rising primary delivered recycled water from a pumping station to a reservoir 10km away.
The downside was that, after a 12 months in operation, there was a couple of 10% reduction in pumping output. The consumer assured me that he had tested the pumps they usually were OK. Therefore, it just had to be a ‘wheel barrow’ within the pipe.
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Rob approached this drawback much as he had throughout his time in SA Water, where he had in depth experience finding isolated partial blockages in deteriorated Cast iron Cement Lined (CICL) water supply pipelines in the course of the 1980’s.
Recording hydraulic gradients
He recorded correct strain readings along the pipeline at a quantity of places (at least 10 locations) which had been surveyed to offer accurate elevation data. The sum of the stress studying plus the elevation at every point (termed the Peizometric Height) gave the hydraulic head at each point. Plotting the hydraulic heads with chainage offers a a number of level hydraulic gradient (HG), very like within the graph below.
Hydraulic Grade (HG) blue line from the friction exams indicated a constant gradient, indicating there was no wheel barrow in the pipe. If there was a wheel barrow within the pipe, the HG would be like the purple line, with the wheel barrow between factors 3 and four km. Graph: R Welke
Given that the HG was fairly straight, there was clearly no blockage alongside the way in which, 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 common friction construct up within the pipeline. To verify this theory, it was determined to ‘pig’ the pipeline. เกจวัดแรงดันแก๊ส concerned using the pumps to pressure 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 efficiency was improved 10% as a outcome of ‘pigging’. Photo: R Welke
The instant enchancment in the pipeline friction from pigging was nothing in want of wonderful. The system head loss had been nearly totally restored to authentic performance, resulting in about a 10% circulate improvement from the pump station. So, as an alternative of discovering a wheel barrow, a biofilm was discovered answerable for pipe friction build-up.
Pipeline performance may be all the time be viewed from an energy 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 enhance in system head as a outcome of biofilm caused the pumps not only to operate at the next head, but that some of the pumping was forced into peak electrical energy tariff. The decreased efficiency pipeline ultimately accounted for about 15% further pumping vitality prices.
Not everybody has a 500NB pipeline!
Well, not everyone has a 500mm pipeline of their irrigation system. So how does that relate to the average irrigator?
A new 500NB
System curve (red line) indicates a biofilm build-up. Black line (broken) reveals system curve after pigging. Biofilm raised pumping costs by up to 15% in one 12 months. Graph: R Welke
PVC pipe has a Hazen & Williams (H&W) friction value of about C=155. When lowered to C=140 (10%) by way of biofilm build-up, the pipe could have the equal of a wall roughness of zero.13mm. The identical roughness in an 80mm pipe represents an H&W C value of one hundred thirty. That’s a 16% discount in move, or a 32% friction loss increase for a similar flow! And that’s simply within the first year!
Layflat hose can have excessive vitality price
A living proof was observed in an power efficiency audit carried out by Tallemenco recently on a turf farm in NSW. A 200m long 3” layflat pipe delivering water to a delicate hose growth had a head lack of 26m head compared with the manufacturers rating of 14m for the same circulate, and with no kinks within the hose! That’s a whopping 85% improve in head loss. Not shocking contemplating that this layflat was transporting algae contaminated river water and lay in the scorching sun all summer time, breeding these little critters on the pipe inside wall.
Calculated when it comes to energy consumption, the layflat hose was responsible for 46% of total pumping power prices via its small diameter with biofilm build-up.
Solution is larger pipe
So, what’s the solution? Move to a larger diameter hose. A 3½” hose has a model new pipe head loss of solely 6m/200m at the same 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 potential 28% saving on pumping power 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 savings. In some instances, 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 greater with time. You can’t get rid of it, however you possibly can control its results, either through energy efficient pipeline design within the first place, or strive ‘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 in regards to the ‘wheel barrow’ within the pipeline after we can’t clarify a pipeline headloss”, stated Rob.
Author Rob Welke has been 52 years in pumping & hydraulics, and never bought 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 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 mostly in Adelaide, South Australia, serving purchasers Australia broad.
Rob runs regular “Pumping System Master Class” ONLINE training programs Internationally to move on his wealth of data he learned from his fifty two years auditing pumping and pipeline techniques all through Australia.
Rob may be contacted on ph +61 414 492 256, or e-mail . LinkedIn – Robert L Welke

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