There’s a wheel barrow in my pipeline!

Rob Welke, from Adelaide, South Australia, took an unusual cellphone from an irrigator within the late 1990’s. “Rob”, he mentioned, “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 mild metal cement lined (MSCL) pipeline development in the previous days. It’s not the primary time Rob had heard of a wheel barrow being left in a big pipeline. Legend has it that it occurred through the rehabilitation of the Cobdogla Irrigation Area, near 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 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 year in operation, there was a couple of 10% reduction in pumping output. The shopper assured me that he had tested the pumps and they were OK. Therefore, it just needed to be a ‘wheel barrow’ in the pipe.
READ: Cheaper irrigation methods for worthwhile farming
Rob approached this drawback much as he had during his time in SA Water, the place he had in depth experience locating isolated partial blockages in deteriorated Cast iron Cement Lined (CICL) water supply pipelines during the 1980’s.
Recording hydraulic gradients
He recorded correct stress readings alongside the pipeline at a number of locations (at least 10 locations) which had been surveyed to offer accurate elevation information. The sum of the strain studying plus the elevation at every level (termed the Peizometric Height) gave the hydraulic head at every level. Plotting the hydraulic heads with chainage provides a multiple level hydraulic gradient (HG), much 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 like the red line, with the wheel barrow between points three and four km. Graph: R Welke
Given that the HG was pretty straight, there was clearly no blockage alongside the way, which might be evident by a sudden change in slope of the HG at that time.
So, it was figured that the head loss should be because of a common friction construct up within the pipeline. To affirm this concept, it was decided to ‘pig’ the pipeline. This concerned utilizing the pumps to pressure two foam cylinders, about 5cm larger than the pipe ID and 70cm lengthy, alongside the pipe from the pump end, exiting into the reservoir.
Two foam pigs emerge from the pipeline. The pipeline performance was improved 10% on account of ‘pigging’. Photo: R Welke
The instant improvement within the pipeline friction from pigging was nothing short of amazing. The system head loss had been nearly totally restored to original efficiency, leading to about a 10% flow enchancment from the pump station. So, instead of finding a wheel barrow, a biofilm was discovered responsible for pipe friction build-up.
Pipeline efficiency may be at all times be viewed from an energy effectivity perspective. Below is a graph displaying the biofilm affected (red line) and restored (black line) system curves for the client’s pipeline, before and after pigging.
READ: 5 Factors to contemplate when choosing irrigation pump
The enhance in system head due to biofilm triggered the pumps not solely to function at a higher head, but that some of the pumping was pressured into peak electricity tariff. The decreased performance pipeline in the end accounted for about 15% extra pumping power prices.
Not everyone 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 costs by as much as 15% in one yr. Graph: R Welke
PVC pipe has a Hazen & Williams (H&W) friction worth of about C=155. When decreased to C=140 (10%) by way of biofilm build-up, the pipe could have the equal of a wall roughness of 0.13mm. The identical roughness in an 80mm pipe represents an H&W C value of one hundred thirty. That’s a 16% discount in move, or a 32% friction loss increase for the same flow! And that’s simply in the first year!
Layflat hose can have excessive power price
A working example was noticed in an energy efficiency audit conducted by Tallemenco lately on a turf farm in NSW. A 200m long 3” layflat pipe delivering water to a delicate hose increase had a head loss of 26m head compared with the manufacturers rating of 14m for a similar circulate, and with no kinks within the hose! That’s a whopping 85% improve in head loss. เกจวัดแรงดันลมดิจิตอล considering that this layflat was transporting algae contaminated river water and lay within the hot sun all summer season, breeding these little critters on the pipe inside wall.
Calculated by means of vitality consumption, the layflat hose was answerable for 46% of complete pumping power costs 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 brand new pipe head lack of only 6m/200m at the identical flow, however when that deteriorates due to biofilm, headloss might rise to solely about 10m/200m as an alternative of 26m/200m, kinks and fittings excluded. That’s a potential 28% saving on pumping energy costs*. In terms of absolute power consumption, if pumping 50ML/yr at 30c/kWh, that’s a saving of $950pa, or $10,700 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 might have to be changed out for a decrease head pump.
Everyone has a wheel barrow in their pipelines, and it only will get larger with time. You can’t do away with it, but you possibly can management its effects, both via energy environment friendly pipeline design within the first place, or strive ‘pigging’ the pipe to get rid of 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’ in the pipeline after we can’t clarify a pipeline headloss”, stated Rob.
Author Rob Welke has been 52 years in pumping & hydraulics, and never bought product in his life! He spent 25 yrs working for SA Water (South Australia) in the late 60’s to 90’s where he performed extensive 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 in Adelaide, South Australia, serving purchasers Australia wide.
Rob runs regular “Pumping System Master Class” ONLINE coaching courses Internationally to cross on his wealth of data he learned from his fifty two years auditing pumping and pipeline systems throughout Australia.
Rob may be contacted on ph +61 414 492 256, or email . LinkedIn – Robert L Welke

Leave a Comment