Drip Allocation with Octopus IV

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Octopus IV

It probably is about the fourth prototype, but the IV actually stands for Intravenous like the gravity drip apparatus used to administer fluids or drugs to patients in medical situations. In this case we are administering measured and adjustable water volumes to individual or groups of adjacent plants at controlled intervals. This occurs so slowly we can guide this moisture vertically down a capped finger sized surge pipe to their root zone to potentially reduce evaporation, pest and weed life support and salt accumulation. The cap should stick out just above the mulch for occasional inspection if plants start wilting.

The use of a transparent bucket demonstrated the hydrology perfectly when the water level in the transparent tub could also be watched. The tipping point influenced by the amount of rocks in the tub could be seen really clearly. Note the spiraling tubes in the overhead photograph and the black valves.

Cross Section Diagram – Water C. is the bottom constant sump volume not allocated, Water A. is the tub volume that is only accessible to the two of the outlets that extend down to the bottom of the tub (two, in case one blocks), Water B. is the total available distribution volume that can be divided up between all the outlets. Note the tipping point for sinking the tub is one parameter adjustable by the flexible tube length and can not be more than the top of the bucket. The tub height sets the lower other general allocation limit when the tub twists and settles on the bottom. Note the IV like bottles serve like funnels to store and distribute their allocation and the time taken to do this will vary depending on the length of tube to the plants and the elevation of this part of the garden bed. A pin vent hole at the top of the bottle ensures varying levels of resistance to flow along the more rigid distribution pipe is not transferred back up to the flow out rate of the octopus. Each bottle could theoretically be receiving the same allocation of water but discharge this at several different varying rates well before the next activation. Taps were moved up to inside the head of the octopus to restrict outlet flows on some outlets and increase allocation out of others as a result. All taps are currently fully open and may not be needed. Four bricks of elevation were used under the bucket or the bottles might have overflowed out of the vent hole. Fewer bricks could probably be used if the taps were used to reduce flow into the bottles and spread allocation over a longer time period)

Note the small inserted plot is the bucket discharging approximately every 6 hours until it was turned off but some water or rain must have been leaking into it. The larger plot was recorded while I was doing a lot of experimentation with this newer prototype. The filling and discharging plots are irregular because of leaks, bottles dropping off tubes, me stealing the water supply to water in new seedlings, rain events and low pressure weather systems. Drip rates down as low as one every 8 seconds are possible and very simple electronic timers can be used to switch these on and off as well if greater times are needed to let the soil dry out a little. These Multipar charts were made possible with the assistance of Henk Buchner from Verge Solutions using a meter normally used for logging water tank levels.

Application to Soil

Installation of drip shafts down to the root zones and finally burial of the feeder lines should complete the installation for one garden bed.

Future Research

The next step is to add four more lines bringing the total to 12 (3 bottles on each of the four sides of the bricks). Technically it would no longer be an octopus by accumulating 12 legs and might have to be called a dodecapus or dozopus maybe but I think octopus has stuck!

If l need extra volume in the bucket to water these points or more points in an expanded garden bed then a linked bucket or buckets that have water levels that feed out and back into the floating tub bucket could achieve this. I might even dangle an extra layer of bottles around the outside to see what the maximum feed lines is that l can get out of one tub. I toyed with the idea of whether the bucket should be suspended with the lines coming out vertically around the edge of the base but I did not see many advantages. I also looked at whether multiple lines of the same length, friction and elevation could drain out of each bottle to further split flows but these are very hard to balance at low inflow rates. Maybe smaller but more numerous bottles and more numerous activations is the key.  The bucket will need covering up soon with the lid that has a mosquito proof pinhole vent and then with cardboard to protect the plastics from the sun. Then all that is left to do is occasionally adjust is the drip-in rate. Hopefully, it will soon be overgrown with thriving plants.

One Comment

  1. Had a problem with such small diameter tub sump siphons self priming before the tub sank on some drip settings but larger diameter poly tubes extending down after the valve seem to have solved this. Cheers! !

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