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 hold package for reinstating cement lining throughout delicate metal cement lined (MSCL) pipeline building in the previous days. It’s not the first time Rob had heard of a wheel barrow being left in a large pipeline. Legend has it that it happened in the course of the rehabilitation of the Cobdogla Irrigation Area, near Barmera, South Australia, in 1980’s. It can also be suspected that it might just have been a plausible excuse for unaccounted friction losses in a model new 1000mm trunk main!
Rob agreed to assist his shopper out. A 500mm dia. PVC rising main delivered recycled water from a pumping station to a reservoir 10km away.
The problem was that, after a 12 months in operation, there was about a 10% discount in pumping output. The consumer assured me that he had examined the pumps and so they were OK. Therefore, it just needed to be a ‘wheel barrow’ in the pipe.
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Rob approached this drawback much as he had during his time in SA Water, the place he had extensive expertise locating 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 accurate strain readings alongside the pipeline at multiple locations (at least 10 locations) which had been surveyed to supply accurate elevation information. The sum of the stress studying plus the elevation at every point (termed the Peizometric Height) gave the hydraulic head at each level. Plotting the hydraulic heads with chainage provides a multiple point hydraulic gradient (HG), very similar to within the graph under.
Hydraulic Grade (HG) blue line from the friction tests indicated a constant gradient, indicating there was no wheel barrow in the pipe. If there was a wheel barrow in the pipe, the HG could be just like the pink 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 along the way, which might be evident by a sudden change in slope of the HG at that time.
So, it was figured that the head loss must be because of a common friction build up within the pipeline. To affirm this concept, it was decided to ‘pig’ the pipeline. This concerned utilizing the pumps to drive two foam cylinders, about 5cm larger than the pipe ID and 70cm long, alongside 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’. Photo: R Welke
The immediate improvement in the pipeline friction from pigging was nothing wanting superb. The system head loss had been almost completely restored to original performance, leading to a few 10% move enchancment from the pump station. So, as a substitute of discovering a wheel barrow, a biofilm was discovered responsible for pipe friction build-up.
Pipeline efficiency could be all the time be viewed from an power effectivity 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 improve in system head as a result of biofilm triggered the pumps not solely to function at a higher 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% extra pumping power prices.
Not everyone 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 prices 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 will have the equal of a wall roughness of zero.13mm. The same roughness in an 80mm pipe represents an H&W C value of 130. That’s a 16% reduction in circulate, or a 32% friction loss improve for the same flow! And that’s simply within the first year!
ตัววัดแรงดันน้ำ can have high energy price
A working example was noticed in an vitality efficiency audit conducted 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 lack of 26m head in contrast with the producers score of 14m for a similar circulate, and with no kinks within the hose! That’s a whopping 85% enhance in head loss. Not surprising contemplating that this layflat was transporting algae contaminated river water and lay within the scorching solar all summer time, breeding those little critters on the pipe inside wall.
Calculated by means of energy consumption, the layflat hose was answerable for 46% of complete pumping energy prices by way of 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 lack of only 6m/200m on the same circulate, however when that deteriorates as a end result of biofilm, headloss could rise to solely about 10m/200m as an alternative of 26m/200m, kinks and fittings excluded. That’s a possible 28% saving on pumping vitality 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 energy savings. In some instances, the pump might have to be modified out for a lower head pump.
Everyone has a wheel barrow of their pipelines, and it solely gets larger with time. You can’t get rid of it, but you can control its results, either via energy 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 nonetheless joke in regards to the ‘wheel barrow’ within the pipeline when we can’t clarify a pipeline headloss”, said Rob.
Author Rob Welke has been fifty two years in pumping & hydraulics, and never sold 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 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 primarily based in Adelaide, South Australia, serving shoppers Australia wide.
Rob runs regular “Pumping System Master Class” ONLINE training courses Internationally to pass on his wealth of knowledge he realized from his 52 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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