Rob Welke, from Adelaide, South Australia, took an unusual cellphone from an irrigator in the late 1990’s. “Rob”, he mentioned, “I suppose 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 hold package for reinstating cement lining throughout mild metal cement lined (MSCL) pipeline building within 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 during the rehabilitation of the Cobdogla Irrigation Area, near Barmera, South Australia, in 1980’s. It can additionally be suspected that it could simply have been a plausible excuse for unaccounted friction losses in a model new 1000mm trunk main!
เครื่องมือวัดความดัน agreed to help his consumer 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 12 months in operation, there was a couple of 10% reduction in pumping output. The consumer assured me that he had tested the pumps they usually have been OK. Therefore, it simply needed 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 intensive expertise locating isolated partial blockages in deteriorated Cast iron Cement Lined (CICL) water supply pipelines through the 1980’s.
Recording hydraulic gradients
He recorded correct strain readings alongside the pipeline at a quantity of locations (at least 10 locations) which had been surveyed to provide accurate elevation data. The sum of the stress studying plus the elevation at each level (termed the Peizometric Height) gave the hydraulic head at each point. Plotting the hydraulic heads with chainage provides a a number of point 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 in the pipe, the HG can be like the pink 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 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 should be because of a common friction construct up within the pipeline. To confirm this theory, it was decided to ‘pig’ the pipeline. This concerned utilizing the pumps to drive two foam cylinders, about 5cm bigger than the pipe ID and 70cm long, alongside the pipe from the pump end, exiting into the reservoir.
Two foam pigs emerge from the pipeline. The pipeline efficiency was improved 10% on account of ‘pigging’. Photo: R Welke
The immediate improvement in the pipeline friction from pigging was nothing wanting wonderful. The system head loss had been nearly completely restored to original performance, leading to a couple of 10% flow enchancment from the pump station. So, as a substitute of finding a wheel barrow, a biofilm was discovered liable for pipe friction build-up.
Pipeline performance can be at all times be seen 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 enhance in system head because of biofilm caused the pumps not solely to operate at a higher head, but that a few of the pumping was compelled into peak electricity tariff. The decreased efficiency pipeline ultimately accounted for about 15% extra pumping power costs.
Not everybody 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) signifies a biofilm build-up. Black line (broken) exhibits system curve after pigging. Biofilm raised pumping prices by as much as 15% in one year. 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 equal of a wall roughness of zero.13mm. The same roughness in an 80mm pipe represents an H&W C worth of one hundred thirty. That’s a 16% reduction in circulate, or a 32% friction loss improve for a similar flow! And that’s simply in the first year!
Layflat hose can have excessive vitality price
A case in point was observed in an power efficiency audit performed by Tallemenco just lately on a turf farm in NSW. A 200m lengthy 3” layflat pipe delivering water to a soft hose increase had a head lack of 26m head in contrast with the producers score of 14m for a similar flow, and with no kinks within the hose! That’s a whopping 85% improve in head loss. Not stunning contemplating that this layflat was transporting algae contaminated river water and lay in the hot sun all summer time, breeding these little critters on the pipe inside wall.
Calculated in phrases of vitality consumption, the layflat hose was responsible for 46% of whole 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 larger diameter hose. A 3½” hose has a model new pipe head lack of solely 6m/200m on the similar move, however when that deteriorates because of biofilm, headloss might rise to only about 10m/200m as a substitute of 26m/200m, kinks and fittings excluded. That’s a possible 28% saving on pumping vitality 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 need to be trimmed or a VFD fitted to potentiate the vitality savings. In some cases, the pump may have to be modified out for a decrease head pump.
Everyone has a wheel barrow of their pipelines, and it only will get larger with time. You can’t do away with it, but you’ll find a way to management its results, both through energy efficient pipeline design within the first place, or try ‘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 concerning the ‘wheel barrow’ within the pipeline when we can’t explain a pipeline headloss”, stated Rob.
Author Rob Welke has been fifty two 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 the place he carried out intensive pumping and pipeline power 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 clients Australia broad.
Rob runs regular “Pumping System Master Class” ONLINE training programs Internationally to move on his wealth of data he realized from his 52 years auditing pumping and pipeline systems all through Australia.
Rob could be contacted on ph +61 414 492 256, or email . LinkedIn – Robert L Welke