There’s a wheel barrow in my pipeline!

Rob Welke, from Adelaide, South Australia, took an unusual phone from an irrigator within the late 1990’s. “Rob”, he mentioned, “I think there’s a wheel barrow in my pipeline. Can you locate it?”

Robert L Welke, Director, Training Manager and Pumping/Hydraulics Consultant

Wheel barrows were used to hold equipment for reinstating cement lining during gentle metal cement lined (MSCL) pipeline development in the outdated days.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 through the rehabilitation of the Cobdogla Irrigation Area, near Barmera, South Australia, in 1980’s. เพรสเชอร์เกจ is also suspected that it might just have been a plausible excuse for unaccounted friction losses in a brand new 1000mm trunk main!

Rob agreed to help his client 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 about a 10% reduction in pumping output. The client assured me that he had examined the pumps and so they had been OK. Therefore, it simply needed to be a ‘wheel barrow’ within the pipe.
READ: Cheaper irrigation methods for profitable farming

Rob approached this problem a lot as he had throughout his time in SA Water, where he had extensive experience finding isolated partial blockages in deteriorated Cast iron Cement Lined (CICL) water provide pipelines in the course of the 1980’s.
Recording hydraulic gradients

He recorded correct strain readings along the pipeline at a number of places (at least 10 locations) which had been surveyed to offer correct elevation information. The sum of the pressure studying plus the elevation at each level (termed the Peizometric Height) gave the hydraulic head at every level. Plotting the hydraulic heads with chainage offers a multiple level hydraulic gradient (HG), very like within the graph under.
Hydraulic Grade (HG) blue line from the friction tests indicated a constant gradient, indicating there was no wheel barrow in the pipe. If there was a wheel barrow within the pipe, the HG can be like the pink 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 means in which, which might be evident by a sudden change in slope of the HG at that time.
So, it was figured that the head loss have to be because of a basic friction construct up in the pipeline. To verify this principle, it was determined to ‘pig’ the pipeline. เกจวัดแรงดัน concerned utilizing 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 efficiency was improved 10% as a outcome of ‘pigging’. Photo: R Welke

The immediate improvement in the pipeline friction from pigging was nothing in need of amazing. The system head loss had been virtually completely restored to authentic efficiency, resulting in about a 10% flow enchancment from the pump station. So, as an alternative of finding a wheel barrow, a biofilm was discovered liable 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.
READ: 5 Factors to consider when selecting irrigation pump

The increase in system head due to biofilm caused the pumps not solely to function at a higher head, but that a few of the pumping was pressured into peak electrical energy tariff. The lowered performance pipeline ultimately accounted for about 15% extra pumping energy costs.
Not everybody has a 500NB pipeline!

Well, not everybody has a 500mm pipeline in 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 costs by up to 15% in one 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 equal of a wall roughness of zero.13mm. The same roughness in an 80mm pipe represents an H&W C value of a hundred thirty. That’s a 16% reduction in circulate, or a 32% friction loss increase for a similar flow! And that’s simply in the first year!

Layflat hose can have excessive vitality cost

A living proof was noticed in an power effectivity audit performed by Tallemenco lately on a turf farm in NSW. A 200m lengthy 3” layflat pipe delivering water to a gentle hose boom had a head lack of 26m head compared with the manufacturers score of 14m for the same flow, and with no kinks in the hose! That’s a whopping 85% enhance in head loss. Not surprising considering that this layflat was transporting algae contaminated river water and lay within the scorching sun all summer time, breeding those little critters on the pipe inside wall.
Calculated in phrases of power consumption, the layflat hose was responsible for 46% of whole pumping energy prices via 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 similar move, however when that deteriorates because of biofilm, headloss may rise to only 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 power financial savings. In some circumstances, the pump could have to be modified out for a lower head pump.
Everyone has a wheel barrow of their pipelines, and it only will get greater with time. You can’t get rid of it, however you’ll be able to management its results, either via power environment friendly pipeline design in 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 nonetheless joke concerning the ‘wheel barrow’ within the pipeline after we can’t explain a pipeline headloss”, mentioned 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) within the late 60’s to 90’s the place he carried out in depth pumping and pipeline vitality 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 clients Australia broad.
Rob runs common “Pumping System Master Class” ONLINE coaching courses Internationally to pass on his wealth of information he realized from his 52 years auditing pumping and pipeline systems throughout Australia.
ไดอะแฟรม ซีล may be contacted on ph +61 414 492 256, www.talle.biz or e mail r.welke@talle.biz . LinkedIn – Robert L Welke

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