There’s a wheel barrow in my pipeline!

Rob Welke, from Adelaide, South Australia, took an uncommon telephone from an irrigator in the late 1990’s. “Rob”, he said, “I assume there’s a wheel barrow in my pipeline. Can you locate it?”
Robert L Welke, Director, Training Manager and Pumping/Hydraulics Consultant
Wheel barrows have been used to hold kit for reinstating cement lining throughout mild steel cement lined (MSCL) pipeline building in the outdated days. It’s not the primary 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, close to Barmera, South Australia, in 1980’s. It can be suspected that it might just have been a believable excuse for unaccounted friction losses in a model 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 12 months in operation, there was about a 10% discount in pumping output. The consumer assured me that he had tested the pumps and they were OK. Therefore, it simply needed to be a ‘wheel barrow’ in the pipe.
READ: Cheaper irrigation methods for profitable farming
Rob approached this problem much as he had throughout his time in SA Water, the place he had intensive 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 alongside the pipeline at multiple areas (at least 10 locations) which had been surveyed to provide correct elevation information. The sum of the pressure studying plus the elevation at each point (termed the Peizometric Height) gave the hydraulic head at every point. Plotting the hydraulic heads with chainage provides a multiple level hydraulic gradient (HG), much like 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 can be like the pink line, with the wheel barrow between factors three and four km. Graph: R Welke
Given that the HG was pretty straight, there was clearly no blockage alongside 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 pinnacle loss should be due to a basic friction construct up within the pipeline. To verify this concept, it was decided to ‘pig’ the pipeline. This involved utilizing the pumps to pressure two foam cylinders, about 5cm bigger than the pipe ID and 70cm long, alongside 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 instant improvement within the pipeline friction from pigging was nothing in need of wonderful. The system head loss had been nearly completely restored to original performance, resulting in a couple of 10% move improvement from the pump station. So, as an alternative of discovering a wheel barrow, a biofilm was found liable for pipe friction build-up.
Pipeline efficiency may be at all times be considered from an power efficiency perspective. Below is a graph exhibiting the biofilm affected (red line) and restored (black line) system curves for the client’s pipeline, earlier than and after pigging.
READ: 5 Factors to consider when selecting irrigation pump
The enhance in system head because of biofilm brought on the pumps not only to operate at the next head, however that some of the pumping was forced into peak electrical energy tariff. The decreased efficiency pipeline in the end accounted for about 15% extra pumping energy costs.
Not everyone 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) signifies a biofilm build-up. Black line (broken) shows system curve after pigging. Biofilm raised pumping costs by up to 15% in one yr. Graph: R Welke
PVC pipe has a Hazen & Williams (H&W) friction worth of about C=155. When reduced to C=140 (10%) via biofilm build-up, the pipe may have the equal of a wall roughness of zero.13mm. The identical roughness in an 80mm pipe represents an H&W C value of 130. That’s a 16% discount in move, or a 32% friction loss increase for the same flow! And that’s just in the first year!
Layflat hose can have high energy price
A working example was observed in an power effectivity audit performed by Tallemenco lately on a turf farm in NSW. A 200m long 3” layflat pipe delivering water to a soft hose growth had a head lack of 26m head in contrast with the producers score of 14m for the same flow, and with no kinks in the hose! That’s a whopping 85% increase in head loss. Not surprising considering 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 answerable for 46% of total pumping energy prices through 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 solely 6m/200m on the same circulate, however when that deteriorates due to biofilm, headloss might rise to only about 10m/200m as a substitute of 26m/200m, kinks and fittings excluded. That’s a potential 28% saving on pumping energy 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 savings. In some circumstances, the pump could have to be modified out for a lower head pump.
Everyone has a wheel barrow of their pipelines, and it solely gets greater with time. You can’t get rid of it, however you can control its results, either via energy efficient 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 about the ‘wheel barrow’ in the pipeline when we can’t clarify a pipeline headloss”, mentioned Rob.
เพรสเชอร์เกจวัดแรงดันน้ำ 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 the place he performed extensive pumping and pipeline vitality 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 in Adelaide, South Australia, serving clients Australia extensive.
Rob runs common “Pumping System Master Class” ONLINE training programs Internationally to pass on his wealth of information he learned from his fifty two years auditing pumping and pipeline methods all through Australia.
Rob may be contacted on ph +61 414 492 256, or e-mail . LinkedIn – Robert L Welke

Scroll to Top