Rob Welke, from Adelaide, South Australia, took an uncommon cellphone from an irrigator in the late 1990’s. “Rob”, he mentioned, “I think 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 hold package for reinstating cement lining throughout mild metal cement lined (MSCL) pipeline building within 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 in the course of the rehabilitation of the Cobdogla Irrigation Area, close to Barmera, South Australia, in 1980’s. It can also be suspected that it may just have been a plausible excuse for unaccounted friction losses in a brand new 1000mm trunk main!
Rob agreed to assist his shopper out. A 500mm dia. PVC rising primary delivered recycled water from a pumping station to a reservoir 10km away.
The downside was that, after a 12 months in operation, there was about a 10% reduction in pumping output. The client assured me that he had examined the pumps and so they have been OK. Therefore, it just had to be a ‘wheel barrow’ within the pipe.
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Rob approached this problem much as he had throughout his time in SA Water, the place he had intensive 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 accurate strain readings alongside the pipeline at multiple locations (at least 10 locations) which had been surveyed to provide 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 point. Plotting the hydraulic heads with chainage gives a multiple point hydraulic gradient (HG), very like in the graph beneath.
Hydraulic Grade (HG) blue line from the friction tests indicated a consistent gradient, indicating there was no wheel barrow in the pipe. If there was a wheel barrow within the pipe, the HG would be just like the purple line, with the wheel barrow between factors 3 and 4 km. Graph: R Welke
Given that the HG was pretty straight, there was clearly no blockage along the way, which might be evident by a sudden change in slope of the HG at that time.
So, it was figured that the top loss have to be because of a basic friction construct up within the pipeline. To verify this theory, it was determined to ‘pig’ the pipeline. This involved utilizing the pumps to force two foam cylinders, about 5cm larger 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% as a end result of ‘pigging’. เกจ์วัดแรงดัน : R Welke
The prompt enchancment within the pipeline friction from pigging was nothing in need of superb. The system head loss had been nearly completely restored to original performance, resulting in about a 10% move 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 energy efficiency perspective. Below is a graph showing 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 due to biofilm brought on the pumps not only to operate at a higher head, however that some of the pumping was compelled into peak electricity tariff. The lowered performance pipeline finally accounted for about 15% further pumping vitality costs.
Not everyone has a 500NB pipeline!
Well, not everybody 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) shows 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%) by way of biofilm build-up, the pipe could have the equal of a wall roughness of zero.13mm. The identical roughness in an 80mm pipe represents an H&W C worth of a hundred thirty. That’s a 16% discount in flow, or a 32% friction loss improve for a similar flow! And that’s just within the first year!
Layflat hose can have high energy cost
A case in point was observed in an power effectivity audit performed by Tallemenco recently on a turf farm in NSW. A 200m lengthy 3” layflat pipe delivering water to a delicate hose boom had a head lack of 26m head in contrast with the producers ranking 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 solar all summer time, breeding those little critters on the pipe inside wall.
Calculated when it comes to power consumption, the layflat hose was answerable for 46% of complete pumping power prices through 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 lack of solely 6m/200m at the similar move, but when that deteriorates as a 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 energy costs*. In phrases of absolute energy 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 have to be trimmed or a VFD fitted to potentiate the energy financial savings. In some cases, the pump may have to be modified out for a lower head pump.
Everyone has a wheel barrow of their pipelines, and it only gets bigger with time. You can’t do away with it, but you can management its results, both through vitality efficient pipeline design within the first place, or attempt ‘pigging’ the pipe to do away with 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”, said Rob.
Author Rob Welke has been fifty two years in pumping & hydraulics, and by no means sold product in his life! He spent 25 yrs working for SA Water (South Australia) in the late 60’s to 90’s where he conducted in depth pumping and pipeline energy 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 purchasers Australia wide.
Rob runs common “Pumping System Master Class” ONLINE training programs Internationally to cross on his wealth of knowledge he realized from his fifty two 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