Correct pressure for dripper irrigation

I thought that I will post about this, in case someone is googling for information about installing a small dripper irrigation system in their garden. They might find my experience useful.

It is just a small area, with ten Veri-Flow drippers and 13mm pipe. There is an automatic timer and pressure-reducer and filter:

Except that when first connected up, there was no pressure-reducer. Result: those drippers sent jets of water up into the air higher than me!

This surprised me, as I have put in dripper irrigation before, and haven't used a pressure-reducer. However, they were in rural locations, where the water pressure from the tap was quite low. At my current premises, it is very high.

The Water Corporation in Western Australia states that they supply pressure anywhere between 15mH (147kPa) and 100mH (980kPa). But I can't find a figure for where I live.

The automatic timer is specified to work between 100kPa and 800kPa. This is it:

https://www.bunnings.com.au/holman-electronic-2-dial-tap-timer_p3120816

So I bought a combined pressure-reducer and filter, which is what you see in the above photo. Here it is:

https://www.bunnings.com.au/holman-13mm-pressure-reducer-and-filter-assembly_p3120097

Put it in, started the timer, ah, now the drippers have jets of water "only" about 2-3 feet high! Very interesting. The Pope Veri-Flow drippers are rated to be adjustable between 0-60 litres/hour -- well, that "0" is wrong, they can't be screwed down enough to cut off the jet of water.

So I examined the specifications of the pressure-reducer. It has 180kPa output. Very interesting, it means that the water from the tap must be well above that, maybe in the order of twice.

Bunnings have a pressure-reducer rated at 100kPa output, that is a direct screw replacement for the one I already have. So, off to Bunnings again:

https://www.bunnings.com.au/pope-100kpa-pressure-poly-reducer_p3431632

That did the trick! So, the lesson learned here is that for a very small dripper irrigation system, what we want is 100kPa. Perhaps with a bigger system, with many more drippers or sprinklers, the flow through the pipes would naturally reduce the pressure to something acceptable, or perhaps a higher-rated pressure-reducer would be OK.

Or, if I was using sprinklers, and actually wanted large sprays of water, then a pressure-reducer could have been dispensed with.

It was a fascinating little exercise. 

Tags: general