Rob Welke, from Adelaide, South Australia, took an uncommon cellphone from an irrigator within the late 1990’s. “Rob”, he stated, “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 carry package for reinstating cement lining throughout 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 large pipeline. Legend has it that it occurred during the rehabilitation of the Cobdogla Irrigation Area, close to Barmera, South Australia, in 1980’s. It is also suspected that it may just have been a believable excuse for unaccounted friction losses in a model new 1000mm trunk main!
Rob agreed to help his consumer out. A 500mm dia. PVC rising main delivered recycled water from a pumping station to a reservoir 10km away.
The drawback was that, after a yr in operation, there was a couple of 10% discount in pumping output. The client assured me that he had examined the pumps they usually had been OK. Therefore, it just had to be a ‘wheel barrow’ within the pipe.
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Rob approached this downside much as he had during his time in SA Water, where he had in depth experience finding isolated partial blockages in deteriorated Cast iron Cement Lined (CICL) water supply pipelines during the 1980’s.
Recording hydraulic gradients
He recorded correct pressure readings alongside the pipeline at a quantity of places (at least 10 locations) which had been surveyed to provide correct elevation information. The sum of the stress reading plus the elevation at every 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 related to within the graph below.
Hydraulic Grade (HG) blue line from the friction tests indicated a consistent gradient, indicating there was no wheel barrow within the pipe. If there was a wheel barrow within the pipe, the HG would 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 finest way, which would be evident by a sudden change in slope of the HG at that point.
So, เกจวัดแรงดันดิจิตอล was figured that the top loss should be due to a general friction build up within the pipeline. To confirm this theory, it was determined to ‘pig’ the pipeline. This involved using the pumps to force two foam cylinders, about 5cm larger than the pipe ID and 70cm long, along 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 prompt enchancment within the pipeline friction from pigging was nothing short of wonderful. The system head loss had been nearly completely restored to unique performance, leading to a few 10% circulate enchancment from the pump station. So, as an alternative of finding a wheel barrow, a biofilm was found responsible for pipe friction build-up.
Pipeline efficiency may be at all times be seen 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.
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The enhance in system head because of biofilm brought on the pumps not solely to function at a better head, however that some of the pumping was pressured into peak electricity tariff. The reduced efficiency pipeline ultimately accounted for about 15% additional pumping power costs.
Not everybody has a 500NB pipeline!
Well, not everyone has a 500mm pipeline of 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 prices by as a lot as 15% in one year. Graph: R Welke
PVC pipe has a Hazen & Williams (H&W) friction worth of about C=155. When reduced to C=140 (10%) via biofilm build-up, the pipe may have the equal of a wall roughness of 0.13mm. The same roughness in an 80mm pipe represents an H&W C value of 130. That’s a 16% reduction in flow, or a 32% friction loss enhance for a similar flow! And that’s just within the first year!
Layflat hose can have excessive energy price
A living proof was noticed in an vitality effectivity audit carried out by Tallemenco recently on a turf farm in NSW. A 200m lengthy 3” layflat pipe delivering water to a delicate hose increase had a head loss of 26m head in contrast with the manufacturers score of 14m for the same move, and with no kinks in the hose! That’s a whopping 85% increase in head loss. Not surprising contemplating that this layflat was transporting algae contaminated river water and lay in the hot sun all summer time, breeding those little critters on the pipe inside wall.
Calculated when it comes to energy consumption, the layflat hose was liable for 46% of total pumping energy prices via its small diameter with biofilm build-up.
Solution is larger pipe
So, what’s the solution? Move to a larger diameter hose. A 3½” hose has a new pipe head lack of solely 6m/200m on the similar move, however when that deteriorates as a outcome of biofilm, headloss might rise to solely about 10m/200m as a substitute 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 need to be trimmed or a VFD fitted to potentiate the vitality savings. In some circumstances, the pump may should be modified out for a decrease head pump.
Everyone has a wheel barrow of their pipelines, and it only gets bigger with time. You can’t eliminate it, however you presumably can management its effects, both through energy environment friendly pipeline design in the first place, or attempt ‘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 once we can’t clarify a pipeline headloss”, said Rob.
Author Rob Welke has been 52 years in pumping & hydraulics, and by no means sold product in his life! He spent 25 yrs working for SA Water (South Australia) within the late 60’s to 90’s where he conducted intensive pumping and pipeline energy 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 training programs Internationally to cross on his wealth of knowledge he learned from his fifty two years auditing pumping and pipeline systems throughout Australia.
Rob could be contacted on ph +61 414 492 256, or email . LinkedIn – Robert L Welke