We are very fortunate to have a prolific spring on the property that supplies all the water we need. While we currently use petrol and diesel-powered pumps to move the water around the farm, we have always planned on using more sustainable methods.The first step is the installation of a water ram pump.
Ram pumps work on the principle of harnessing the “water hammer” effect – when you suddenly stop a descending column of water, the force produced is much greater than the weight of the water alone. This force, when used in a cycle can pump water considerably higher than the level it starts from. Water flowing downhill is passed through the ram pump and most of it is returned to the flow downstream while a small amount gets pushed up the hill. It’s inefficient but a small flow of water 24/7 using no external energy is a pretty good deal. Our ram pump delivers a constant 4L/minute to a header tank 40m above the spring.
The ram pump before installation. It only has 2 moving parts (both valves) – one visible and one inside the base of the dome. Wikipedia has a good overview of the how ram pumps work. While there are plenty of references available online I was fortunate to get the original instructions with my ram pump.
The ram pump installed at the lowest point I could practically manage – about 4m below the point at which the water is collected. To the right of the pump is the path of the spring. Water that sprays out of the pump as waste will drain back into the stream. I still need to put a cement base under the ram – it will be in danger of hammering itself down into the bank otherwise.
The drive pipe heading down to the pump. It’s just over 30m of galvanised 40mm (inch and a half) steel pipe. There is a gentle bend in the pipe to get over some immovable rocks. The ideal is to have a perfectly straight, rigid pipe to minimise water friction but a gentle curve is better than sharp bends.
The reservoir at the top of the spring is made from a 200L plastic drum cut in half and lined with polythene. This ensures the drive pipe is always full and gives any sediment in the spring a chance to settle before the water goes to the pump. The inflow on the right is the overflow from the neighbour’s water catchment.
Here is a small video clip of the pump in action
Lessons from my installation
While I mentioned there are plenty of resources online regarding hydraulic ram pumps, most are related to theoretical performance and pretty diagrams of how the pumps work. Here are a few lessons I’ve learned from trial and error (and wish someone had told me before I started).
First up, and this is not a good thing to hear if you are considering “having a go” like I did, you have to set up the ram exactly as it’s going to be used in order to test it. As I will explain in the points below, there’s no dry runs, loose fits or shake-downs. Unless the ram pump is set up completely (and properly) it just won’t go. I spent a good number of frustrating hours trying to troubleshoot the operation of the pump before I realised this useful point.
The drive pipe – needs to be as rigid and straight as possible. It must be airtight for the pump to work. I did a loose fit test with everything assembled and air was getting in the pipe. Water does not compress but air does. Air in the drive pipe cripples the pump and you will get erratic cycling or none at all.
The reservoir – needs to have enough of a store of water to ensure air never gets in the drive pipe.
The ram pump – needs to be level for the valves to operate correctly and efficiently. Installing valves on both the drive pipe entry and the exit to the delivery pipe is a good idea to save you having to refill these every time you fiddle with the pump. The drive pipe valve acts as the on/off tap for the pump.
The delivery pipe – needs to be attached and be at the correct length and height. The reason for this is the weight of water in the delivery pipe, at the required height creates backpressure at the pump which balances the pressure of the water in the delivery pipe. Without the delivery pipe connected the pump will never cycle freely. My first instinct was to get the pump working, then attach the delivery pipe. This single tip would have saved me hours of cursing and tinkering and hopefully it will save you some time if you undertake a similar project :-)
After all the planning, work (and a fair bit of swearing) I forgot to mention the absolute joy you feel the first time you see the pump cycling, delivering water with no external energy.