There’s a wheel barrow in my pipeline!

Rob Welke, from Adelaide, South Australia, took an unusual cellphone from an irrigator within the late 1990’s. “Rob”, he stated, “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 delicate steel cement lined (MSCL) pipeline development in the old 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 through the rehabilitation of the Cobdogla Irrigation Area, near Barmera, South Australia, in 1980’s. It can additionally be suspected that it might just have been a believable excuse for unaccounted friction losses in a brand new 1000mm trunk main!
Rob agreed to help his shopper out. A 500mm dia. First rising major 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% discount in pumping output. The consumer assured me that he had examined the pumps they usually had been OK. Therefore, it simply had to be a ‘wheel barrow’ within the pipe.
READ: Cheaper irrigation methods for worthwhile 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 Censored recorded accurate stress readings alongside the pipeline at a quantity of locations (at least 10 locations) which had been surveyed to supply accurate elevation info. The sum of the strain studying plus the elevation at every level (termed the Peizometric Height) gave the hydraulic head at each level. Plotting the hydraulic heads with chainage provides a a quantity of level hydraulic gradient (HG), very comparable to in the graph under.
Hydraulic Grade (HG) blue line from the friction checks 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 pink line, with the wheel barrow between points three and four km. Graph: R Welke
Given that the HG was fairly straight, there was clearly no blockage alongside the means in which, which might be evident by a sudden change in slope of the HG at that point.
So, it was figured that the pinnacle loss have to be due to a basic friction build up in the pipeline. To confirm this principle, it was determined to ‘pig’ the pipeline. This concerned utilizing the pumps to drive two foam cylinders, about 5cm bigger 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% on account of ‘pigging’. Photo: R Welke
The instant enchancment in the pipeline friction from pigging was nothing in need of superb. The system head loss had been nearly totally restored to original efficiency, leading to about a 10% move enchancment from the pump station. So, as a substitute of finding a wheel barrow, a biofilm was discovered answerable for pipe friction build-up.
Pipeline performance may be always be seen from an power effectivity 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 suppose about when choosing irrigation pump
The enhance in system head as a result of biofilm caused the pumps not solely to function at the next head, but that some of the pumping was forced into peak electricity tariff. The decreased efficiency pipeline in the end accounted for about 15% additional pumping vitality costs.
Not everyone has a 500NB pipeline!
Well, not everyone 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) reveals system curve after pigging. Biofilm raised pumping costs 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%) via biofilm build-up, the pipe will have the equal of a wall roughness of zero.13mm. The similar roughness in an 80mm pipe represents an H&W C value of one hundred thirty. That’s a 16% reduction in circulate, or a 32% friction loss improve for a similar flow! And that’s just in the first year!
Layflat hose can have high vitality cost
A living proof was observed in an vitality effectivity audit conducted by Tallemenco just lately on a turf farm in NSW. A 200m lengthy 3” layflat pipe delivering water to a gentle hose growth had a head loss of 26m head in contrast with the manufacturers ranking of 14m for the same circulate, and with no kinks within 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 scorching solar all summer time, breeding these little critters on the pipe inside wall.
Calculated in terms of power consumption, the layflat hose was answerable for 46% of whole pumping vitality 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 lack of only 6m/200m at the same circulate, however when that deteriorates due to biofilm, headloss could rise to only about 10m/200m instead of 26m/200m, kinks and fittings excluded. That’s a potential 28% saving on pumping power costs*. In phrases of absolute vitality 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 vitality financial savings. In some instances, 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 greater with time. You can’t do away with it, however you presumably can control its results, both by way of power efficient pipeline design in the first place, or try ‘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 concerning the ‘wheel barrow’ within the pipeline when we can’t clarify a pipeline headloss”, mentioned Rob.
Author Rob Welke has been fifty two years in pumping & hydraulics, and never sold product in his life! He spent 25 yrs working for SA Water (South Australia) in 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 based in Adelaide, South Australia, serving shoppers Australia broad.
Rob runs common “Pumping System Master Class” ONLINE coaching programs Internationally to move on his wealth of information he discovered from his fifty two years auditing pumping and pipeline methods throughout Australia.
Rob may be contacted on ph +61 414 492 256, or email . LinkedIn – Robert L Welke

Leave a Comment