There’s a wheel barrow in my pipeline!

Rob Welke, from Adelaide, South Australia, took an unusual phone 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 have been used to hold package for reinstating cement lining during delicate steel cement lined (MSCL) pipeline development in the old 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 occurred during the rehabilitation of the Cobdogla Irrigation Area, close to Barmera, South Australia, in 1980’s. It can be suspected that it might just have been a plausible excuse for unaccounted friction losses in a model new 1000mm trunk main!
Rob agreed to assist his shopper out. A 500mm dia. PVC rising main delivered recycled water from a pumping station to a reservoir 10km away.
The problem was that, after a year in operation, there was about a 10% discount in pumping output. The shopper assured me that he had tested the pumps they usually have been OK. Therefore, it just had to be a ‘wheel barrow’ in the pipe.
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Rob approached this drawback much as he had throughout his time in SA Water, where he had intensive expertise locating isolated partial blockages in deteriorated Cast iron Cement Lined (CICL) water supply pipelines in the course of the 1980’s.
Recording hydraulic gradients
He recorded accurate pressure readings along the pipeline at a quantity of locations (at least 10 locations) which had been surveyed to offer correct elevation information. The sum of the stress reading plus the elevation at each point (termed the Peizometric Height) gave the hydraulic head at each level. Plotting the hydraulic heads with chainage gives a multiple point hydraulic gradient (HG), very like in the graph under.
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 within the pipe, the HG could be just like the red line, with the wheel barrow between factors three and four km. Graph: R Welke
Given that the HG was pretty straight, there was clearly no blockage along the method in which, which would be evident by a sudden change in slope of the HG at that point.
So, it was figured that the pinnacle loss have to be as a end result of a basic friction build up in the pipeline. To verify this theory, it was decided to ‘pig’ the pipeline. This involved utilizing the pumps to pressure two foam cylinders, about 5cm bigger than the pipe ID and 70cm lengthy, alongside the pipe from the pump finish, exiting into the reservoir.
Two foam pigs emerge from the pipeline. The pipeline efficiency was improved 10% as a result of ‘pigging’. Photo: R Welke
The instant improvement in the pipeline friction from pigging was nothing wanting superb. The system head loss had been nearly completely restored to unique performance, resulting in a few 10% circulate improvement from the pump station. So, as an alternative of discovering a wheel barrow, a biofilm was found answerable for pipe friction build-up.
Pipeline efficiency can be always be considered from an vitality efficiency perspective. Below is a graph exhibiting 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 improve in system head because of biofilm triggered the pumps not solely to operate at a higher head, however that a variety of the pumping was compelled into peak electricity tariff. The decreased efficiency pipeline in the end accounted for about 15% extra 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 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 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%) through 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 value of one hundred thirty. That’s a 16% reduction in move, or a 32% friction loss enhance for a similar flow! And that’s simply within the first year!
เกจ์วัดแรงดันแก๊ส can have excessive energy value
A living proof was observed in an vitality efficiency audit conducted by Tallemenco recently on a turf farm in NSW. A 200m long 3” layflat pipe delivering water to a delicate hose boom had a head lack of 26m head in contrast with the producers rating of 14m for a similar flow, and with no kinks within the hose! That’s a whopping 85% increase in head loss. Not shocking contemplating that this layflat was transporting algae contaminated river water and lay within the scorching solar all summer time, breeding these little critters on the pipe inside wall.
Calculated when it comes to power consumption, the layflat hose was responsible for 46% of whole pumping vitality prices through its small diameter with biofilm build-up.
Solution is bigger pipe
So, what’s the solution? Move to a larger diameter hose. A 3½” hose has a brand new pipe head lack of only 6m/200m at the similar move, however when that deteriorates because of biofilm, headloss could rise to only about 10m/200m as an alternative of 26m/200m, kinks and fittings excluded. That’s a possible 28% saving on pumping energy costs*. In terms 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 savings. In some circumstances, the pump may have to be changed out for a lower head pump.
Everyone has a wheel barrow in their pipelines, and it only will get bigger with time. You can’t get rid of it, but you can management its effects, either by way of vitality efficient pipeline design in the first place, or strive ‘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 when we can’t explain a pipeline headloss”, mentioned Rob.
Author Rob Welke has been 52 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 in depth pumping and pipeline power 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 extensive.
Rob runs common “Pumping System Master Class” ONLINE coaching programs Internationally to move on his wealth of information he learned from his 52 years auditing pumping and pipeline systems all through Australia.
Rob can be contacted on ph +61 414 492 256, or e mail . LinkedIn – Robert L Welke

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