Rob Welke, from Adelaide, South Australia, took an uncommon telephone from an irrigator in the late 1990’s. “Rob”, he said, “I suppose 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 gentle steel 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 happened during the rehabilitation of the Cobdogla Irrigation Area, near Barmera, South Australia, in 1980’s. It is also suspected that it may simply have been a believable excuse for unaccounted friction losses in a brand new 1000mm trunk main!
Rob agreed to help his consumer out. A 500mm dia. PVC rising major delivered recycled water from a pumping station to a reservoir 10km away.
The downside was that, after a yr in operation, there was a few 10% discount in pumping output. The shopper assured me that he had examined the pumps and they have been OK. Therefore, it simply had to be a ‘wheel barrow’ within the pipe.
READ: Cheaper irrigation strategies for profitable farming
Rob approached this problem 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 in the course of the 1980’s.
Recording hydraulic gradients
He recorded correct stress readings along the pipeline at a number of places (at least 10 locations) which had been surveyed to supply correct elevation data. The sum of the strain studying plus the elevation at each point (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 in the graph beneath.
Hydraulic Grade (HG) blue line from the friction exams indicated a constant gradient, indicating there was no wheel barrow within the pipe. If there was a wheel barrow in the pipe, the HG would be like the purple line, with the wheel barrow between points 3 and 4 km. Graph: R Welke
Given that the HG was fairly straight, there was clearly no blockage along the way in which, which might be evident by a sudden change in slope of the HG at that point.
So, it was figured that the head loss should be because of a general friction build up within the pipeline. To confirm 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 lengthy, along the pipe from the pump end, exiting into the reservoir.
Two foam pigs emerge from the pipeline. The pipeline performance was improved 10% as a outcome of ‘pigging’. Photo: R Welke
The immediate enchancment in the pipeline friction from pigging was nothing wanting amazing. The system head loss had been virtually completely restored to authentic performance, leading to a couple of 10% circulate enchancment from the pump station. So, instead of finding a wheel barrow, a biofilm was found responsible for pipe friction build-up.
Pipeline ENERGY EFFICIENCY
Pipeline efficiency could be all the time be seen from an energy effectivity perspective. Below is a graph exhibiting the biofilm affected (red line) and restored (black line) system curves for the client’s pipeline, earlier than and after pigging.
READ: 5 Factors to contemplate when choosing irrigation pump
The increase in system head because of biofilm brought on the pumps not only to operate at a better head, but that a variety of the pumping was compelled into peak electricity tariff. The reduced efficiency pipeline in the end accounted for about 15% additional pumping power prices.
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) shows system curve after pigging. Biofilm raised pumping prices by as a lot as 15% in a single 12 months. Graph: R Welke
PVC pipe has a Hazen & Williams (H&W) friction value 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 0.13mm. The similar roughness in an 80mm pipe represents an H&W C value of a hundred thirty. That’s a 16% reduction in flow, or a 32% friction loss enhance for a similar flow! And that’s simply within the first year!
Layflat hose can have excessive vitality value
A living proof was observed in an energy effectivity audit carried out by Tallemenco recently on a turf farm in NSW. A 200m lengthy 3” layflat pipe delivering water to a gentle hose increase had a head loss of 26m head compared with the producers rating of 14m for the same flow, and with no kinks in the hose! That’s a whopping 85% improve in head loss. Not shocking considering that this layflat was transporting algae contaminated river water and lay in the sizzling solar all summer time, breeding those little critters on the pipe inside wall.
Calculated in phrases of energy consumption, the layflat hose was liable for 46% of whole pumping vitality prices 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 new pipe head lack of solely 6m/200m at the identical flow, but when that deteriorates due to biofilm, headloss could rise to solely about 10m/200m as an alternative of 26m/200m, kinks and fittings excluded. That’s a potential 28% saving on pumping vitality costs*. In phrases of absolute power 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 need to be trimmed or a VFD fitted to potentiate the vitality savings. In some circumstances, the pump might should be changed out for a decrease head pump.
Everyone has a wheel barrow of their pipelines, and it solely gets larger with time. You can’t do away with it, but you’ll have the ability to control its effects, either by way of vitality environment friendly pipeline design in the first place, or attempt ‘pigging’ the pipe to eliminate that wheel barrow!!
As for the wheel barrow in Rob’s client’s pipeline, the legend lives on. “ เกจวัดแรงดันไนโตรเจน and I nonetheless joke about the ‘wheel barrow’ in the pipeline when we can’t clarify a pipeline headloss”, stated Rob.
Author Rob Welke has been 52 years in pumping & hydraulics, and by no means 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 conducted extensive 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 in Adelaide, South Australia, serving shoppers Australia broad.
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
Share