Rob Welke, from Adelaide, South Australia, took an unusual cellphone from an irrigator in the late 1990’s. “Rob”, he stated, “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 had been used to carry equipment for reinstating cement lining throughout mild metal cement lined (MSCL) pipeline building in the outdated days.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 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 can be suspected that it may simply have been a plausible excuse for unaccounted friction losses in a brand new 1000mm trunk main!
Rob agreed to help his consumer out. A 500mm dia. PVC rising main delivered recycled water from a pumping station to a reservoir 10km away.
The downside was that, after a 12 months in operation, there was about a 10% reduction in pumping output. The consumer assured me that he had tested the pumps and they had been OK. Therefore, it simply had to be a ‘wheel barrow’ within the pipe.
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Rob approached this downside a lot as he had during his time in SA Water, where he had intensive expertise locating isolated partial blockages in deteriorated Cast iron Cement Lined (CICL) water provide pipelines during the 1980’s.
Recording hydraulic gradients
He recorded correct stress readings alongside the pipeline at a number of areas (at least 10 locations) which had been surveyed to offer correct elevation info. The sum of the pressure reading plus the elevation at every level (termed the Peizometric Height) gave the hydraulic head at every point. Plotting the hydraulic heads with chainage offers a a number of level hydraulic gradient (HG), very like in the graph beneath.
Hydraulic Grade (HG) blue line from the friction exams indicated a consistent gradient, indicating there was no wheel barrow within the pipe. If there was a wheel barrow within the pipe, the HG can be like the red line, with the wheel barrow between factors three 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 point.
So, it was figured that the top loss have to be as a outcome of a basic friction build up in the pipeline. To verify เพรสเชอร์เกจไฮดรอลิค , it was determined to ‘pig’ the pipeline. This involved utilizing the pumps to drive 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 performance was improved 10% because of ‘pigging’. Photo: R Welke
The immediate improvement in the pipeline friction from pigging was nothing wanting superb. The system head loss had been virtually completely restored to original efficiency, resulting in about a 10% move improvement from the pump station. So, as a substitute of finding a wheel barrow, a biofilm was found answerable for pipe friction build-up.
Pipeline efficiency may be always be considered from an vitality 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 enhance in system head due to biofilm caused the pumps not only to function at a better head, but that a variety of the pumping was pressured into peak electrical energy tariff. The reduced efficiency pipeline finally accounted for about 15% further pumping power prices.
Not everyone has a 500NB pipeline!
Well, not everybody 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) exhibits 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 worth of about C=155. When reduced to C=140 (10%) via biofilm build-up, the pipe could have the equivalent of a wall roughness of zero.13mm. The similar roughness in an 80mm pipe represents an H&W C value of one hundred thirty. That’s a 16% discount in flow, or a 32% friction loss increase for a similar flow! And that’s simply within the first year!
Layflat hose can have high power value
A living proof was noticed in an vitality effectivity audit performed by Tallemenco just lately on a turf farm in NSW. A 200m lengthy 3” layflat pipe delivering water to a soft hose growth had a head loss of 26m head compared with the manufacturers ranking of 14m for the same circulate, and with no kinks in the hose! That’s a whopping 85% enhance in head loss. Not shocking contemplating that this layflat was transporting algae contaminated river water and lay in the sizzling solar all summer time, breeding these little critters on the pipe inside wall.
Calculated in terms of power 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 bigger diameter hose. A 3½” hose has a model new pipe head loss of solely 6m/200m on the identical move, however when that deteriorates due to biofilm, headloss could rise to solely about 10m/200m instead of 26m/200m, kinks and fittings excluded. That’s a possible 28% saving on pumping energy 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 have to be trimmed or a VFD fitted to potentiate the power savings. In some instances, the pump might should be modified out for a lower head pump.
Everyone has a wheel barrow in their pipelines, and it solely will get greater with time. You can’t do away with it, however you presumably can management its effects, either through power environment friendly pipeline design in 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 still 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 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 conducted in depth 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 purchasers Australia broad.
Rob runs common “Pumping System Master Class” ONLINE coaching courses Internationally to move on his wealth of information he discovered from his fifty two years auditing pumping and pipeline techniques all through Australia.
Rob could be contacted on ph +61 414 492 256, or email . LinkedIn – Robert L Welke