There’s a wheel barrow in my pipeline!

Rob Welke, from Adelaide, South Australia, took an uncommon telephone from an irrigator within the late 1990’s. “Rob”, he said, “I suppose there’s a wheel barrow in my pipeline. Can you locate it?”
Robert L Welke, Director, Training Manager and Pumping/Hydraulics Consultant
Wheel barrows were used to hold equipment for reinstating cement lining during mild metal cement lined (MSCL) pipeline construction 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 happened through the rehabilitation of the Cobdogla Irrigation Area, close to Barmera, South Australia, in 1980’s. It can be suspected that it could just have been a plausible 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 drawback was that, after a year in operation, there was about a 10% reduction in pumping output. The client assured me that he had examined the pumps they usually had been OK. Therefore, it just needed 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, where 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 quantity of places (at least 10 locations) which had been surveyed to supply accurate elevation data. เกจวัดแรงดันไนโตรเจนราคา of the strain studying plus the elevation at every level (termed the Peizometric Height) gave the hydraulic head at each point. Plotting the hydraulic heads with chainage gives a multiple level hydraulic gradient (HG), very similar to in the graph below.
Hydraulic Grade (HG) blue line from the friction checks indicated a constant gradient, indicating there was no wheel barrow in the pipe. If there was a wheel barrow within the pipe, the HG could be just like the purple line, with the wheel barrow between points 3 and four km. Graph: R Welke
Given that the HG was pretty straight, there was clearly no blockage along the way, which might be evident by a sudden change in slope of the HG at that time.
So, it was figured that the pinnacle loss have to be as a end result of a basic friction build up within the pipeline. To confirm this concept, it was decided to ‘pig’ the pipeline. This concerned using the pumps to force two foam cylinders, about 5cm bigger than the pipe ID and 70cm lengthy, along the pipe from the pump end, exiting into the reservoir.
Two foam pigs emerge from the pipeline. The pipeline performance was improved 10% as a outcome of ‘pigging’. Photo: R Welke
The immediate improvement within the pipeline friction from pigging was nothing wanting wonderful. The system head loss had been nearly totally restored to unique efficiency, leading to about a 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 efficiency may be at all times 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, before and after pigging.
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The improve in system head because of biofilm triggered the pumps not only to operate at the next head, however that a variety of the pumping was pressured into peak electricity tariff. The lowered efficiency pipeline finally accounted for about 15% further pumping vitality prices.
Not everybody has a 500NB pipeline!
Well, not everyone has a 500mm pipeline in their irrigation system. So how does that relate to the average irrigator?
A new 500NB
System curve (red line) indicates a biofilm build-up. Black line (broken) exhibits system curve after pigging. Biofilm raised pumping costs by up to 15% in a single 12 months. Graph: R Welke
PVC pipe has a Hazen & Williams (H&W) friction value of about C=155. When decreased to C=140 (10%) by way of biofilm build-up, the pipe may have the equivalent of a wall roughness of 0.13mm. The same roughness in an 80mm pipe represents an H&W C worth of a hundred thirty. That’s a 16% discount in flow, or a 32% friction loss improve for a similar flow! And that’s simply in the first year!
Layflat hose can have excessive energy value
A case in point was noticed in an energy efficiency audit conducted by Tallemenco just lately on a turf farm in NSW. A 200m long 3” layflat pipe delivering water to a soft hose boom had a head lack of 26m head compared with the producers ranking of 14m for the same move, and with no kinks in the hose! That’s a whopping 85% increase in head loss. Not stunning contemplating that this layflat was transporting algae contaminated river water and lay within the scorching solar all summer, breeding those little critters on the pipe inside wall.
Calculated by method of vitality consumption, the layflat hose was responsible for 46% of total pumping vitality costs via its small diameter with biofilm build-up.
Solution is bigger pipe
So, what’s the solution? Move to a bigger diameter hose. A 3½” hose has a brand new pipe head loss of solely 6m/200m on the similar circulate, but when that deteriorates due to biofilm, headloss might rise to solely about 10m/200m as a substitute of 26m/200m, kinks and fittings excluded. That’s a potential 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 must be trimmed or a VFD fitted to potentiate the vitality savings. In some instances, the pump may have to be changed out for a lower head pump.
Everyone has a wheel barrow of their pipelines, and it solely gets larger with time. You can’t eliminate it, but you’ll be able to management its results, both through power efficient 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 concerning the ‘wheel barrow’ within the pipeline after we can’t clarify a pipeline headloss”, said Rob.
Author Rob Welke 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 where he performed extensive 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 based mostly in Adelaide, South Australia, serving clients Australia broad.
Rob runs common “Pumping System Master Class” ONLINE training programs Internationally to move on his wealth of data he discovered from his 52 years auditing pumping and pipeline techniques throughout Australia.
Rob may be contacted on ph +61 414 492 256, or email . LinkedIn – Robert L Welke

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