There’s a wheel barrow in my pipeline!

Rob Welke, from Adelaide, South Australia, took an uncommon cellphone from an irrigator in the late 1990’s. “Rob”, he stated, “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 had been used to hold equipment for reinstating cement lining throughout mild metal cement lined (MSCL) pipeline construction within the outdated days.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 occurred during the rehabilitation of the Cobdogla Irrigation Area, near Barmera, South Australia, in 1980’s. It can additionally be suspected that it may just have been a believable excuse for unaccounted friction losses in a brand 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 problem was that, after a 12 months in operation, there was a couple of 10% discount in pumping output. The consumer assured me that he had examined the pumps they usually have been OK. Therefore, it just had to be a ‘wheel barrow’ within the pipe.
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Rob approached this problem a lot as he had throughout his time in SA Water, the place he had in depth expertise locating isolated partial blockages in deteriorated Cast iron Cement Lined (CICL) water supply pipelines during the 1980’s.
Recording hydraulic gradients
He recorded accurate pressure readings alongside the pipeline at multiple areas (at least 10 locations) which had been surveyed to offer correct elevation info. The sum of the stress reading plus the elevation at every point (termed the Peizometric Height) gave the hydraulic head at every level. Plotting the hydraulic heads with chainage provides a a quantity of point hydraulic gradient (HG), much like in the graph under.
Hydraulic Grade (HG) blue line from the friction tests 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 like the red line, with the wheel barrow between points three and four km. Graph: R Welke
Given that the HG was fairly straight, there was clearly no blockage along the best way, which would be evident by a sudden change in slope of the HG at that time.
So, it was figured that the top loss have to be as a result of a general friction build up in the pipeline. To affirm this principle, it was decided to ‘pig’ the pipeline. This involved using the pumps to drive two foam cylinders, about 5cm bigger than the pipe ID and 70cm long, along the pipe from the pump end, exiting into the reservoir.
Two foam pigs emerge from the pipeline. The pipeline efficiency was improved 10% on account of ‘pigging’. เกจวัดแรงดันอาร์กอน : R Welke
The prompt enchancment in the pipeline friction from pigging was nothing wanting wonderful. The system head loss had been almost completely restored to unique efficiency, resulting in about a 10% move improvement from the pump station. So, as a substitute of finding a wheel barrow, a biofilm was discovered liable for pipe friction build-up.
Pipeline performance can be all the time be viewed from an power efficiency perspective. Below is a graph showing 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 increase in system head because of biofilm caused the pumps not solely to function at the next head, but that a few of the pumping was compelled into peak electrical energy tariff. The decreased efficiency pipeline in the end accounted for about 15% further pumping vitality prices.
Not everyone has a 500NB pipeline!
Well, not everybody has a 500mm pipeline in 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 prices by as much as 15% in one 12 months. Graph: R Welke
PVC pipe has a Hazen & Williams (H&W) friction worth of about C=155. When reduced to C=140 (10%) through biofilm build-up, the pipe could have the equal of a wall roughness of 0.13mm. The same roughness in an 80mm pipe represents an H&W C worth of a hundred thirty. That’s a 16% reduction in flow, or a 32% friction loss increase for the same flow! And that’s just in the first year!
Layflat hose can have excessive energy price
A case in point was observed in an energy effectivity audit conducted by Tallemenco lately on a turf farm in NSW. A 200m long 3” layflat pipe delivering water to a soft hose boom had a head loss of 26m head in contrast with the manufacturers score of 14m for a similar circulate, and with no kinks within the hose! That’s a whopping 85% improve in head loss. Not surprising 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 by method of vitality consumption, the layflat hose was responsible for 46% of total pumping vitality prices 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 model new pipe head loss of solely 6m/200m at the similar circulate, however when that deteriorates because of biofilm, headloss may rise to solely about 10m/200m as a substitute of 26m/200m, kinks and fittings excluded. That’s a possible 28% saving on pumping vitality costs*. In phrases 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 must be trimmed or a VFD fitted to potentiate the power savings. In some instances, the pump could should be changed out for a lower head pump.
Everyone has a wheel barrow in their pipelines, and it only gets greater with time. You can’t eliminate it, but you can control its results, both via power efficient pipeline design in 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 in regards to the ‘wheel barrow’ within the pipeline after we can’t explain a pipeline headloss”, said Rob.
Author Rob Welke has been fifty two years in pumping & hydraulics, and never offered product in his life! He spent 25 yrs working for SA Water (South Australia) within the late 60’s to 90’s where he performed intensive 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 clients Australia broad.
Rob runs common “Pumping System Master Class” ONLINE training programs Internationally to pass on his wealth of knowledge he realized from his fifty two years auditing pumping and pipeline systems throughout Australia.
Rob may be contacted on ph +61 414 492 256, or email . LinkedIn – Robert L Welke

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