Reply To: Ex Air ministry Alcon Pumps

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My pump saga has been an interesting one. My original irrigation system was a bit of a hotchpotch of bits and pieces I had picked up over the years that included the Villiers/Alcon pump. In 2011 I purchased the Hunter MP2000 Rotators and found straight away the Villiers pump would not supply enough pressure. It always took 3+ minutes to pull water up from a well and knew it was therefore not performing as it should. I dropped on the Honda/Clark pump, it was better (26m or 85ft max head), but still not really enough pressure. I revisited some of my early training in pump performance graphs, the pressure and flow rates required for differing irrigation systems. I then got a very secondhand Honda/Loncin thermoplastic pump that supplied near optimal pressure, nearly 35 psi. If fact this was better than that stated in the manufacturer’s performance graph. But did not like using it, the priming filler cap was small and fiddly, it had been left outside, nuts and bolts could not be undone without damage or breaking. The engine was thirsty and ran a bit rough, it really needed a good overhaul, but did not fancy the probable drilling out of snapped studs. The next year I came across a Robin/Koshin SEH-50X for peanuts, the pump is top of the range with a 30m or 100ft head. Knew if I took the pump off it and mated it with the new Honda engine, fitting a new seal too. I would have a brilliant as new bit of kit and that was what I used until 2021. To buy one new today would be £350-500. What I did not know was the Robin engine was a good one. So I mated that up to the Clark pump and put it away for use as a spare. The additional benefit was where both engine shafts showed evidence of wear at the position where the rotary part of the seal is meant to gain a fixed grip on the shaft. By swapping them over, it placed them in different positions. In other words, the seal gripped onto an unworn part of both shafts.

In 2021 I was given the Evenshower Oscillating Spraylines. I wanted to use it instead of the Hunter Rotators, because although I could get good pressure from the pump. Slime that formed in the over-ground supply pipe used to block up the filter in short order, reducing flow. Spraylines do not need the higher pressure offered by the Koshin pump, so used the Robin/Clark pump instead. It is less noisy and sips less fuel than the bigger GX160 Honda. Did some testing, this system requires a delivery of 7GPM at 12 – 15 psi. The label on the recently acquired 1½” Alcon pump states the maximum head is 66ft (28.5 psi), but do not have a performance graph. So do not know the pressure when the flow is 7GPM. But fully expect it to be fine as the flow rate is so low, especially after seeing David’s video with the impressive jet of water going into the pond and still maintaining 20 psi. I have not started the Villiers/Alcon unit since 2011. Am going to try to get the JAP 2a working and see if it pumps. If it does I shall then carry out suction vacuum and delivery pressure tests. As I will have the testing kit out, will do the same for the Villiers/Alcon.

Have checked my 2a pump set and there is a hole on the section of casting that goes from the engine to the pump body on the carburettor side next to the bottom casting web. So if any water gets past the seal will drain out and not get into the engine. But I think my pump is a bog standard one, whereas David’s may have been a special order. The Villiers/Alcon has this section of casting spaced off the crankcase and I recall water coming out of it before I replaced the seal. Have thought again about the Villiers/Alcon not achieving what seems to be the recognized reading of a minimum of 20 in-Hg on a vacuum test for single stage water pumps. As it only has a head of 66ft, it may correspondingly have a lower ability to lift. It will be interesting again to test the pump and make some comparisons with others now I have more experience with them. When I last did it 14 years ago I was more interested in getting enough pressure to operate the Hunter system.

Villiers/Alcon sets were the most common pumps used by small market gardeners around Evesham for their almost universal sprayline irrigation. Larger growers had bigger kit. Evenproducts were an Evesham company and still exist, but the old premises now exclusively manufacture corrugated round steel water tanks with butyl liners. They once did have a large irrigation department and may have sold Villiers/Alcon pumps that they would match to an irrigation system’s requirements. My father had a two cylinder Lister diesel engine permanently fixed in a pump house attached to a single stage centrifugal pump. It was fed from a reservoir which in turn was fed from a borehole that was put in the 1950’s and went down 70-90ft to water bearing limestone strata. It never stopped running, but could not supply enough water into the reservoir in 24 hours for the irrigation system to run at full capacity. The water needed to be carefully managed in dry periods. The diesel pump could supply enough water for two large rainguns or a big field scale sprinkler system. But on the smaller parcels of land away from the main holding, a small petrol pump pulled water from a well and fed spraylines. A big pump would drain the well too quickly, he had a Villiers/Alcon unit. The two wells I use on separate pieces of land contain 750 and 1250 gallons respectively and take 2 – 3 days to refill. A sprayline can be as much as 16off 15’ sections long and would require a supply of 800 gallons per hour. For a good soaking, it needs to run for at least 2½ hours, or 2000 gallons. It is horses for courses and where an understanding of supply capacity, pump performance graphs, flow rates, delivery pipe sizing, pressure requirements and precipitation rates is needed. Everything has to link up for a successful system. Most mobile petrol pumps are the single stage centrifugal type with a manufacturer’s maximum pressure ranging between 20 – 35 metres of head (29 – 50 psi) so can be used for a small irrigation system. Including an Alcon. As long as the flow rate does not reduce the pressure to below that what is required at the nozzles.

Where I was caught out was the Hunter specifications stated a 16’ radius at the minimum pressure of 25 psi. It never achieved this, it was more like 13’, the rotators got stuck, the water was not atomized correctly. At 30 psi performance was nearer to that specified, at 35 psi, even better. It’s why I tried multiple pumps. But not all was in vain, from memory each pump was about £30, the seals less and I have ended up with 3 good pumps, 4 if the Villiers seal is not leaking, 5 if the JAP works. More important to me, I have greatly enjoyed the journey.

Locally we have not had any proper rain since the end of February, so my wells and irrigation had been a lifeline too. The ground water levels have not dropped as I would have expected though, after refilling, the water in the wells is only about a foot lower than a ‘normal’ dry period!

Foot valves are used where there is an opportunity to eliminate manually priming the pump (filling it with water before starting) and often fitted to a semi or fully permanently fixed pump’s suction pipe. They keep water in the pipe, so there is little lag between starting and actual delivery. For mobile units where the suction hose is removed out of the water after each use, they do not have a purpose.

Most pumps used for horticulture have an internal flap valve as David has described. These prevent water from going out of the pump body when not in use, or when being primed before starting. When the pump starts with water in the body the action of the impeller within the volute creates a vacuum in the suction pipe and this ‘lifts’ water into the pump. It is when this process is going through it’s motion that the seal is under the greatest test. If air is sucked through the seal, or through the hose connection, the negative pressure of the vacuum is not sufficient to lift water by the amount required. So when a pump does not pump, or takes ages to start delivering water, firstly check all the connections on the suction side. If these are fine, then the seal is suspect. You can leave water in the pump between uses and not prime, relying on the flap valve to retain enough water in the body. From experience, this extends the time to takes to start delivering water. So I always top up the body anyway, unless it is used for stop/start operations within a working day. But after finding signs of corrosion on the steel engine shaft of each pump I have taken apart. I now ALWAYS drain them when I disconnect the hoses. Although I did this before because when I picked them up, water could slosh out from the flap valve, usually onto my leg, or in the van.