Rob Welke, from Adelaide, South Australia, took an uncommon phone from an irrigator in the late 1990’s. “Rob”, he stated, “I assume there’s a wheel barrow in my pipeline. Can you find it?”
Robert L Welke, Director, Training Manager and Pumping/Hydraulics Consultant
Wheel barrows had been used to carry package for reinstating cement lining during mild metal cement lined (MSCL) pipeline development within the outdated days.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 happened through the rehabilitation of the Cobdogla Irrigation Area, near Barmera, South Australia, in 1980’s. It is also suspected that it might simply have been a believable excuse for unaccounted friction losses in a brand new 1000mm trunk main!
Rob agreed to assist his shopper out. A 500mm dia. เกจวัดแรงดันน้ำประปา rising main delivered recycled water from a pumping station to a reservoir 10km away.
The problem was that, after a yr in operation, there was a couple of 10% reduction in pumping output. The shopper assured me that he had tested the pumps and they have been OK. Therefore, it just needed to be a ‘wheel barrow’ within the pipe.
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Rob approached this drawback a lot as he had during 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 correct pressure readings along the pipeline at a quantity of areas (at least 10 locations) which had been surveyed to offer correct elevation data. The sum of the pressure reading plus the elevation at each point (termed the Peizometric Height) gave the hydraulic head at each level. Plotting the hydraulic heads with chainage provides a multiple point hydraulic gradient (HG), very like in the graph beneath.
Hydraulic Grade (HG) blue line from the friction exams indicated a consistent gradient, indicating there was no wheel barrow within the pipe. If there was a wheel barrow in the pipe, the HG can be just like the red line, with the wheel barrow between factors three and 4 km. Graph: R Welke
Given that the HG was fairly straight, there was clearly no blockage alongside the finest way, which would be evident by a sudden change in slope of the HG at that time.
So, it was figured that the pinnacle loss must be as a outcome of a general friction construct up in the pipeline. To verify this concept, it was determined to ‘pig’ the pipeline. This concerned utilizing the pumps to pressure two foam cylinders, about 5cm bigger than the pipe ID and 70cm long, along the pipe from the pump finish, 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 prompt enchancment in the pipeline friction from pigging was nothing short of amazing. The system head loss had been almost completely restored to original performance, resulting in about a 10% circulate improvement from the pump station. So, as a substitute of discovering a wheel barrow, a biofilm was found answerable for pipe friction build-up.
Pipeline ENERGY EFFICIENCY
Pipeline efficiency could be all the time be seen 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, before and after pigging.
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The enhance in system head due to biofilm brought on the pumps not solely to operate at a higher head, however that a few of the pumping was compelled into peak electricity tariff. The decreased efficiency pipeline ultimately accounted for about 15% additional pumping vitality costs.
Not everyone has a 500NB pipeline!
Well, not everyone has a 500mm pipeline of their irrigation system. So how does that relate to the average irrigator?
A new 500NB
System curve (red line) signifies a biofilm build-up. Black line (broken) shows system curve after pigging. Biofilm raised pumping prices by up to 15% in a single 12 months. Graph: R Welke
PVC pipe has a Hazen & Williams (H&W) friction worth 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 zero.13mm. The identical roughness in an 80mm pipe represents an H&W C value of 130. That’s a 16% discount in flow, or a 32% friction loss improve for a similar flow! And that’s just in the first year!
Layflat hose can have high energy price
A case in point was noticed in an vitality efficiency audit performed by Tallemenco recently on a turf farm in NSW. A 200m long 3” layflat pipe delivering water to a gentle hose growth had a head lack of 26m head in contrast with the manufacturers score of 14m for a similar circulate, and with no kinks within the hose! That’s a whopping 85% enhance in head loss. Not shocking considering that this layflat was transporting algae contaminated river water and lay in the hot sun all summer season, breeding these little critters on the pipe inside wall.
Calculated when it comes to energy consumption, the layflat hose was answerable for 46% of complete pumping energy prices via its small diameter with biofilm build-up.
Solution is larger 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 similar circulate, however when that deteriorates as a end result of biofilm, headloss might rise to only about 10m/200m as a substitute of 26m/200m, kinks and fittings excluded. That’s a potential 28% saving on pumping power costs*. In terms of absolute energy 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 circumstances, the pump might should be changed out for a lower head pump.
Everyone has a wheel barrow of their pipelines, and it only will get bigger with time. You can’t get rid of it, but you presumably can management its results, either by way of power 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 nonetheless joke in regards to the ‘wheel barrow’ within the pipeline after we can’t clarify a pipeline headloss”, mentioned 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 where he carried out extensive 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 based mostly in Adelaide, South Australia, serving shoppers Australia wide.
Rob runs regular “Pumping System Master Class” ONLINE training programs Internationally to pass on his wealth of data he discovered from his fifty two years auditing pumping and pipeline techniques all through Australia.
Rob may be contacted on ph +61 414 492 256, www.talle.biz or email r.welke@talle.biz . LinkedIn – Robert L Welke
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