Rob Welke, from Adelaide, South Australia, took an uncommon cellphone from an irrigator in the late 1990’s. “Rob”, he mentioned, “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 package for reinstating cement lining during gentle metal cement lined (MSCL) pipeline development within the previous days. It’s not the first time Rob had heard of a wheel barrow being left in a big pipeline. Legend has it that it happened during the rehabilitation of the Cobdogla Irrigation Area, close to Barmera, South Australia, in 1980’s. It is also suspected that it could simply have been a plausible excuse for unaccounted friction losses in a model new 1000mm trunk main!
Rob agreed to help his shopper 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 yr in operation, there was about a 10% discount in pumping output. The shopper assured me that he had tested the pumps and they have been OK. Therefore, it just had to be a ‘wheel barrow’ within the pipe.
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Rob approached this downside much as he had throughout his time in SA Water, where he had in depth experience finding isolated partial blockages in deteriorated Cast iron Cement Lined (CICL) water supply pipelines during the 1980’s.
Recording hydraulic gradients
He recorded accurate pressure readings alongside the pipeline at multiple places (at least 10 locations) which had been surveyed to supply correct elevation info. The sum of the strain studying plus the elevation at each level (termed the Peizometric Height) gave the hydraulic head at every point. 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 exams indicated a constant gradient, indicating there was no wheel barrow in the pipe. If there was a wheel barrow in the pipe, the HG could be just like the purple line, with the wheel barrow between points 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 pinnacle loss must be because of a basic friction build up in the pipeline. To affirm this concept, it was decided to ‘pig’ the pipeline. This involved using the pumps to force two foam cylinders, about 5cm bigger than the pipe ID and 70cm long, alongside 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 outcome of ‘pigging’. Photo: R Welke
The instant improvement in the pipeline friction from pigging was nothing wanting amazing. The system head loss had been virtually totally restored to unique performance, leading to a few 10% circulate improvement from the pump station. So, as a substitute of discovering a wheel barrow, a biofilm was found responsible for pipe friction build-up.
Pipeline efficiency may be all the time be viewed from an energy 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 enhance in system head because of biofilm caused the pumps not solely to operate at the next head, but that a few of the pumping was forced into peak electricity tariff. The decreased efficiency pipeline ultimately accounted for about 15% additional pumping energy prices.
Not everyone has a 500NB pipeline!
Well, not everyone has a 500mm pipeline of their irrigation system. So how does that relate to the typical irrigator?
A new 500NB
System curve (red line) indicates a biofilm build-up. Black line (broken) exhibits system curve after pigging. Biofilm raised pumping prices by as a lot as 15% in one 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 may have the equal of a wall roughness of 0.13mm. The similar 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 increase for a similar flow! And that’s just within the first year!
Layflat hose can have excessive vitality price
A working example was noticed in an energy effectivity audit conducted 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 producers score 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 hot solar all summer season, breeding these little critters on the pipe inside wall.
Calculated in terms of vitality consumption, the layflat hose was responsible for 46% of total pumping power prices by way of 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 new pipe head loss of solely 6m/200m at the identical move, but when that deteriorates as a result of biofilm, headloss could rise to solely about 10m/200m as a substitute of 26m/200m, kinks and fittings excluded. เกจวัดอาร์กอน 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 energy financial savings. In some cases, the pump might have to be modified out for a lower head pump.
Everyone has a wheel barrow in their pipelines, and it only gets greater with time. You can’t get rid of it, however you probably can management its results, either through energy efficient pipeline design in the first place, or attempt ‘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’ within the pipeline after we can’t clarify a pipeline headloss”, said Rob.
Author Rob Welke has been fifty two years in pumping & hydraulics, and never offered 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 coaching programs Internationally to cross on his wealth of data he learned from his 52 years auditing pumping and pipeline techniques throughout Australia.
Rob could be contacted on ph +61 414 492 256, or email . LinkedIn – Robert L Welke