Tidy Towns - Hydraulic Ram Pump

Water Conservation Project: Hydraulic Ram Pump

In keeping with our green credentials, Abbeyleix Tidy Towns has recently delivered an innovative Water Harvesting Project which is using hydraulic ram technology. This unique project is providing a free and sustainable source of water (using no outside source of power other than the kinetic energy of flowing water) to the allotment garden on the grounds of St Michael's and All Angels at the southern end of Abbeyleix.

Michael Malone, a local engineer with an expertise in this field, provided the necessary help to get the project off the ground. The water ram is placed by the culvert underneath the entrance to The South National School and can be viewed from the footpath by the Ballacolla road.

The ram pumps water up to two header tanks (IBCs) which are located at the back of the allotments. There is an outflow pipe to return unused water back to the stream once the tanks are full. The project has attracted a lot of attention and training has already been provided to the Portlaoise Men’s Shed so that they can become familiar with the concept and replicate the project elsewhere.

Further information can be got from Michael Malone (mmalone@laoiscoco.ie) or Triona Casey (tcasey@laoiscoco.ie).

Excerpt from article in The Farmers Journal - 7th July 2016 . Download scan of article.

A ram pump offers a cheap alternative to a traditional fuel or electric pump and can be easily constructed, writes William Conlon.

Following a recent article in the Irish Farmers Journal on a ram pump which did not require electricity or fuel to work, we were contacted by Michael Malone, senior executive engineer with Laois County Council, and Michael Meade, an electrician with Laois County Council.

They have been promoting the use of a ram pump on farms for many years as part of the work of the Midland Energy Agency, having shown demonstrations at the National Ploughing Championships in 2013 and 2015. They intend to teach farmers how to construct their own low-cost ram pump for as little as €50. This cost is associated with buying the fittings required for the pump only, all of which can be purchased at your local hardware store. The most expensive cost associated with constructing your own pump is in relation to the piping required, but no matter what water system you implement on your farm, piping will always be required. Also, labour is not taken into account in the cost of the construction as it is a system that a farmer can easily construct themselves.

It is easy to get confused as to how exactly the ram pump works, but Michael took me through the process step by step. It is his hope that this information becomes more readily available to farmers and that it encourages more farmers to take the step towards making their own pump.

The cost of connecting to a mains water supply can go into the thousands depending on where in the country you are. This ram pump could be a low-cost alternative for many farmers, especially those with a stream or river going through land, which could be isolated from a mains water connection or electricity.

How it works

The pump comprises a non-return spring valve, a non-return flap valve, a T-joint and several joiners (as can be seen in the diagram on the right).

When water flows into the pump, the flap valve is open and the spring valve is shut. Water flows in through the tee joint and is directed through the open flap valve where it goes back into the stream/river. When the water builds up enough momentum, it pulls up the flap valve and slams it shut.

The water in the pump has nowhere to go, so pressure builds up in the pump. When the pressure rises up high enough, it will push against the plate of the non-return spring valve. This causes the spring valve to open, which lets a small plug of water into the discharge line and generally goes to a reservoir tank. The pressure in the pump now drops, which closes the spring valve and opens the flap valve once more. The cycle then repeats itself over and over again without any intervention.

Considerations

Water feeds into the pump from the pipe that extends upstream in a river/stream. The outlet of this pipe must be higher than the pump by at least 3ft to get a good flow. While this might sound like a large drop, it is easily achieved in most streams that have any sort of flow. If the river is very flat, it just entails going further upstream with the pipe.

Depending on the drop in the river, the pipe could have to vary between 20m and 200m in length to achieve an adequate flow. The pipe does not have to be suspended above the stream/river to get an adequate flow and can be left on the floor of the stream/river.

For the pump to work properly, there must be back pressure on the outlet pipe, which means it must be filled with water. This can be easily achieved if the pump is not pumping very high or far, but if the water is being pumped over flat ground, then two simple steps can be taken to ensure back pressure. Fitting a valve to the outlet pipe and partly closing it will provide adequate back pressure; otherwise, simply putting the pipe at a height after the pump will also work. Something as simple as hanging the pipe from a tree will provide the required back pressure.

Generally speaking, the inlet pipe into the pump is larger than the discharge pipe. The main reason for this is that 88% to 90% of the water that comes down through the pipe will flow through the flap valve and back into the river/stream with the other 10% to 12% going through the discharge pipe and up to a storage tank. Inlet pipes are recommended to be at least one inch in diameter.

The higher the end of the inlet pipe, the faster the flow will be as the water will gain more momentum as it comes down from a height. As the water flows through the inlet pipe to the pump it has kinetic energy. If you bring the water to a stop, it turns this kinetic energy into pressure, which will work to open the non-return spring valve. If you have a high flow in a pump and a large hose with a valve on the end, when you close the quick valve you get a thump on the end, which is known as water hammer. Water hammer will reduce the efficiency of the system and therefore reduces the flow down to the pump. To combat this, rigid pipe should be used a couple of metres in front of the pump to help reduce the effects of water hammer. The rigid pipe can be gun barrel which is advisable, but PVC or ABS pipe can also be used.

Due to this water hammer effect, the pump must be secured to something solid such as a cement block.

The feed pipe should be the same diameter the entire way back up and have no bends as this will reduce the flow down the pipes. It is advisable to use brass valves rather than plastic as plastic flap valves are very light with the result that the flap closes much earlier than the brass type, which gives a lower flow rate and lower pressure in the pipe.

Maintenance

There is very little maintenance with this system, with any maintenance required relatively inexpensive.

If under constant work, flap valves usually last about 12 months but they are cheap and easily replaced.

The spring non-return valve can get a little bit of dirt in it, but all that is required is to easily disconnect it and clean it.

Otherwise, a filter can be placed upstream at the end of the pipe to prevent dirt from getting into the system.

Optional extras

A pressure vessel is optional on this size of a pump as its only function is to cushion the force generated when the flap valve slams shut (water hammer). It would be needed on larger pumps as the force generated by the water hammer could be enough to pull a pump out of its anchor. A pressure gauge can also be incorporated into the design but, again, it is not necessary for the system to work.

· Further information can be got from Michael Malone (mmalone@laoiscoco.ie) or Triona Casey (tcasey@laoiscoco.ie). A full schematic of the pump can be found on www.midlandenergyagency.ie

Installation options

Michael Malone showed the Irish Farmers Journal three different systems to demonstrate how versatile these pumps are:

· The first system was a demonstration pump set up at a local fire station where water was flowing down from a height of less than 4ft into the pump and then being pumped to the top of a 50ft training tower at ease.

· There was also a pump installed at a local community garden where water is being pumped to two reservoir tanks that are then used to water all the plants. This system was placed in a stream, but there was very little fall on the stream so the inlet pipe had to extend 150m upstream to get an adequate flow. It was then pumped 80m to the tanks. No gun barrel was used in this system with 32mm diameter blue polyethene (MPDE) piping feeding directly into the pipe.

· The third system was installed by a local farmer. Water came from a well over 75m away to the pump. It was pumped a further 410m to a reservoir tank that is used to feed two water troughs for 65 steers throughout the summer. This farmer discovered that the flow from one pump was not adequate to provide water for this number of cattle, so he installed two pumps to work together. These pumps have separate inlet pipes but the discharge pipes are linked. Another solution would have been to install a wider diameter pump, or in many cases increased storage tank volume will solve this.