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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 said, “I think 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used to carry kit for reinstating cement lining throughout gentle steel cement lined (MSCL) pipeline development in the outdated days.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 through 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 believable excuse for unaccounted friction losses in a brand new 1000mm trunk main!
Rob agreed to assist his client out. A 500mm dia. PVC rising major delivered recycled water from a pumping station to a reservoir 10km away.
The downside was that, after a yr in operation, there was a couple of 10% discount in pumping output. The client assured me that he had tested the pumps and they were OK. Therefore, it simply had to be a ‘wheel barrow’ in the pipe.
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Rob approached this problem much as he had during his time in SA Water, the place he had in depth experience locating isolated partial blockages in deteriorated Cast iron Cement Lined (CICL) water supply pipelines through the 1980’s.
Recording hydraulic gradients
He recorded accurate stress readings along the pipeline at a number of areas (at least 10 locations) which had been surveyed to supply accurate elevation data. The sum of the stress studying plus the elevation at every point (termed the Peizometric Height) gave the hydraulic head at every level. Plotting the hydraulic heads with chainage offers a multiple level hydraulic gradient (HG), very like within the graph below.
Hydraulic Grade (HG) blue line from the friction tests indicated a constant gradient, indicating there was no wheel barrow within the pipe. If there was a wheel barrow within the pipe, the HG would be like the purple 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 would be evident by a sudden change in slope of the HG at that point.
So, it was figured that the top loss must be due to a basic friction build up in the pipeline. To verify this concept, it was decided 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% as a result of ‘pigging’. Photo: R Welke
The prompt enchancment within the pipeline friction from pigging was nothing wanting amazing. The system head loss had been virtually completely restored to unique efficiency, resulting in a few 10% flow enchancment from the pump station. So, as เกจวัดแรงดันไนโตรเจน of discovering a wheel barrow, a biofilm was found answerable for pipe friction build-up.
Pipeline ENERGY EFFICIENCY
Pipeline efficiency can be at all times be viewed from an vitality efficiency 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.
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The increase in system head due to biofilm triggered the pumps not solely to operate at the next head, but that a few of the pumping was compelled into peak electrical energy tariff. The reduced performance pipeline ultimately 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 common 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 up to 15% in a single yr. Graph: R Welke
PVC pipe has a Hazen & Williams (H&W) friction value of about C=155. When lowered to C=140 (10%) via biofilm build-up, the pipe could have the equivalent of a wall roughness of 0.13mm. The similar 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 a similar flow! And that’s just in the first year!
Layflat hose can have high vitality price
A case in point was observed in an power effectivity audit performed by Tallemenco recently on a turf farm in NSW. A 200m lengthy 3” layflat pipe delivering water to a soft hose growth had a head lack of 26m head compared with the manufacturers ranking of 14m for the same flow, and with no kinks in the hose! That’s a whopping 85% enhance in head loss. Not surprising considering that this layflat was transporting algae contaminated river water and lay within the hot sun all summer time, breeding these little critters on the pipe inside wall.
Calculated by means of energy consumption, the layflat hose was responsible for 46% of complete pumping energy costs via 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 new pipe head lack of solely 6m/200m at the identical flow, but when that deteriorates due to biofilm, headloss could rise to solely about 10m/200m as an alternative of 26m/200m, kinks and fittings excluded. That’s a potential 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 $10,700 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 may should be modified out for a decrease head pump.
Everyone has a wheel barrow in their pipelines, and it only will get larger with time. You can’t do away with it, however you can management its results, either by way of power 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 still joke in regards to the ‘wheel barrow’ within the pipeline once we can’t clarify a pipeline headloss”, mentioned Rob.
Author Rob Welke has been fifty two years in pumping & hydraulics, and by no means offered product in his life! He spent 25 yrs working for SA Water (South Australia) in the late 60’s to 90’s where he carried out intensive pumping and pipeline energy 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 purchasers Australia broad.
Rob runs regular “Pumping System Master Class” ONLINE coaching courses Internationally to move on his wealth of information he learned from his 52 years auditing pumping and pipeline methods all through Australia.
Rob may 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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