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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 stated, “I think 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carry equipment for reinstating cement lining during delicate metal cement lined (MSCL) pipeline development within the outdated days.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 occurred through the rehabilitation of the Cobdogla Irrigation Area, close to Barmera, South Australia, in 1980’s. It is also suspected that it could just have been a plausible excuse for unaccounted friction losses in a model new 1000mm trunk main!
Rob agreed to help his client 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 year in operation, there was about a 10% discount in pumping output. The shopper assured me that he had examined the pumps they usually were OK. Therefore, it simply had to be a ‘wheel barrow’ within the pipe.
READ: Cheaper irrigation strategies for profitable farming
Rob approached this drawback a lot as he had during his time in SA Water, where he had in depth expertise finding isolated partial blockages in deteriorated Cast iron Cement Lined (CICL) water provide pipelines through the 1980’s.
Recording hydraulic gradients
He recorded correct strain readings alongside the pipeline at multiple locations (at least 10 locations) which had been surveyed to supply correct elevation information. The sum of the pressure reading plus the elevation at every level (termed the Peizometric Height) gave the hydraulic head at each level. Plotting the hydraulic heads with chainage offers a a quantity of level hydraulic gradient (HG), much like in the graph beneath.
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 can be just like the red line, with the wheel barrow between factors 3 and four km. Graph: R Welke
Given that the HG was pretty straight, there was clearly no blockage along the method in which, which would be evident by a sudden change in slope of the HG at that time.
So, it was figured that the top loss must be as a end result of a basic friction construct up in the pipeline. To verify this principle, it was determined to ‘pig’ the pipeline. This concerned using the pumps to drive two foam cylinders, about 5cm larger than the pipe ID and 70cm lengthy, alongside the pipe from the pump end, exiting into the reservoir.
เกจวัดแรงดันnuovafima emerge from the pipeline. The pipeline efficiency was improved 10% because of ‘pigging’. Photo: R Welke
The instant improvement in the pipeline friction from pigging was nothing short of wonderful. The system head loss had been almost completely restored to authentic performance, leading to a couple of 10% move enchancment from the pump station. So, instead of discovering a wheel barrow, a biofilm was found liable for pipe friction build-up.
Pipeline ENERGY EFFICIENCY
Pipeline efficiency may be always be seen from an vitality effectivity 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.
READ: 5 Factors to think about when selecting irrigation pump
The enhance in system head due to biofilm brought on the pumps not solely to function at the next head, but that some of the pumping was compelled into peak electrical energy tariff. The reduced efficiency pipeline ultimately accounted for about 15% extra pumping energy prices.
Not everybody 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) signifies a biofilm build-up. Black line (broken) shows system curve after pigging. Biofilm raised pumping prices by as a lot as 15% in one yr. Graph: R Welke
PVC pipe has a Hazen & Williams (H&W) friction value of about C=155. When decreased to C=140 (10%) through biofilm build-up, the pipe may have the equal of a wall roughness of 0.13mm. The identical roughness in an 80mm pipe represents an H&W C value of a hundred thirty. That’s a 16% reduction in move, or a 32% friction loss enhance for the same flow! And that’s simply in the first year!
Layflat hose can have excessive vitality cost
A living proof was noticed in an energy efficiency audit carried out by Tallemenco recently on a turf farm in NSW. A 200m lengthy 3” layflat pipe delivering water to a gentle hose boom had a head lack of 26m head in contrast with the manufacturers ranking of 14m for the same flow, and with no kinks within the hose! That’s a whopping 85% improve in head loss. Not shocking 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 when it comes to energy consumption, the layflat hose was responsible for 46% of whole pumping power prices by way of 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 new pipe head lack of solely 6m/200m on the same circulate, however when that deteriorates due to biofilm, headloss could rise to only about 10m/200m instead of 26m/200m, kinks and fittings excluded. That’s a possible 28% saving on pumping power costs*. In phrases 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 have to be trimmed or a VFD fitted to potentiate the power savings. In some instances, the pump may need to be modified out for a lower head pump.
Everyone has a wheel barrow in their pipelines, and it only gets bigger with time. You can’t eliminate it, but you’ll be able to control its effects, both via power environment friendly pipeline design within the first place, or try ‘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 concerning the ‘wheel barrow’ in the pipeline once we can’t explain a pipeline headloss”, said Rob.
Author Rob Welke has been 52 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 where he performed in depth 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 primarily based in Adelaide, South Australia, serving clients Australia broad.
Rob runs regular “Pumping System Master Class” ONLINE training courses Internationally to move on his wealth of information he learned from his 52 years auditing pumping and pipeline techniques throughout Australia.
Rob could be contacted on ph +61 414 492 256, www.talle.biz or e mail r.welke@talle.biz . LinkedIn – Robert L Welke
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