There’s a wheel barrow in my pipeline!

Rob Welke, from Adelaide, South Australia, took an uncommon cellphone from an irrigator within the late 1990’s. “Rob”, he mentioned, “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 package for reinstating cement lining throughout mild steel 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 occurred through the rehabilitation of the Cobdogla Irrigation Area, near Barmera, South Australia, in 1980’s. It can additionally be suspected that it might simply have been a believable excuse for unaccounted friction losses in a model new 1000mm trunk main!
Rob agreed to assist his client out. A 500mm dia. PVC rising primary delivered recycled water from a pumping station to a reservoir 10km away.
The problem was that, after a year in operation, there was a few 10% reduction in pumping output. The consumer assured me that he had examined the pumps and they had been OK. Therefore, it just had to be a ‘wheel barrow’ in the pipe.
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Rob approached this downside a lot as he had throughout 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 through the 1980’s.
Recording hydraulic gradients
He recorded accurate strain readings alongside the pipeline at a quantity of locations (at least 10 locations) which had been surveyed to provide correct elevation info. The sum of the pressure reading plus the elevation at every point (termed the Peizometric Height) gave the hydraulic head at each level. Plotting the hydraulic heads with chainage gives a a quantity of point hydraulic gradient (HG), very related to within the graph below.
Hydraulic Grade (HG) blue line from the friction checks indicated a constant gradient, indicating there was no wheel barrow within the pipe. If there was a wheel barrow within the pipe, the HG could be just like the red line, with the wheel barrow between factors three and 4 km. Graph: R Welke
Given that the HG was pretty straight, there was clearly no blockage along the means in which, which might be evident by a sudden change in slope of the HG at that point.
So, it was figured that the top loss should be as a outcome of a basic friction construct up in the pipeline. To affirm this principle, it was determined to ‘pig’ the pipeline. This concerned using the pumps to pressure two foam cylinders, about 5cm larger than the pipe ID and 70cm long, 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 end result of ‘pigging’. Photo: R Welke
The instant improvement in the pipeline friction from pigging was nothing short of amazing. The system head loss had been nearly completely restored to unique efficiency, resulting in a couple of 10% move enchancment from the pump station. So, as a substitute 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 seen from an energy 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 enhance in system head because of biofilm brought on the pumps not solely to function at the next head, but that some of the pumping was pressured into peak electrical energy tariff. The reduced efficiency pipeline ultimately accounted for about 15% further pumping power costs.
Not everybody has a 500NB pipeline!
Well, not everybody has a 500mm pipeline of their irrigation system. So how does that relate to the common 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 a single year. Graph: R Welke
PVC pipe has a Hazen & Williams (H&W) friction worth of about C=155. When reduced to C=140 (10%) through biofilm build-up, the pipe will have the equivalent 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 flow, or a 32% friction loss enhance for a similar flow! And that’s simply within the first year!
Layflat hose can have excessive vitality cost
A working example was noticed in an energy efficiency audit carried out by Tallemenco lately 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 in contrast with the manufacturers score of 14m for the same circulate, and with no kinks in 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 within the scorching sun all summer, breeding these little critters on the pipe inside wall.
Calculated by way of vitality consumption, the layflat hose was answerable for 46% of complete 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 larger diameter hose. A 3½” hose has a new pipe head lack of solely 6m/200m on the identical move, 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 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 financial savings. In some instances, the pump may have to be modified out for a decrease head pump.
Everyone has a wheel barrow of their pipelines, and it only gets bigger with time. You can’t eliminate it, however you’ll have the ability to management its effects, both via vitality environment friendly pipeline design in the first place, or strive ‘pigging’ the pipe to do away with 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’ within the pipeline when we can’t explain a pipeline headloss”, stated Rob.
เกจวัดแรงดันน้ำประปา has been fifty two years in pumping & hydraulics, and by no means sold product in his life! He spent 25 yrs working for SA Water (South Australia) within the late 60’s to 90’s where he carried out extensive 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 mostly in Adelaide, South Australia, serving shoppers Australia extensive.
Rob runs common “Pumping System Master Class” ONLINE training programs Internationally to cross on his wealth of knowledge he learned from his fifty two years auditing pumping and pipeline systems throughout 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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