The purpose of this tutorial is to facilitate the understanding, design, manufacture and installation of a water elevation system called "Ram pump".
The hydraulic ram system was invented in 1797 by Joseph-Michel Montgolfier, the man who built the first hot air balloon in 1782 with his brother, Jacques-Étienne. He was immediately criticized by his contemporaries who associated him with the theories of perpetual movement, which were considered heresies at the time.
It was not until 1857 that a patent was filed by Ernest Sylvain Bollée, which improved and made Montgolfier's invention a reality.
Since then, it has been widely used in the French and European countryside, and is now established in America and Africa in regions where fuel supplies are difficult or expensive.
The hydraulic ram pump is a water elevation system whose operation depends solely on the driving force of the water, without any other external intervention. In concrete terms, this makes possible to pump water from a source (river, lake, stream) and use it higher to irrigate crops, water livestock or for any other domestic use.
The ram pump has several advantages:
Do not use plastic material for the ram, whether valves or flaps, as they will wear out very quickly during operation..
To be recovered:
Without accident, this process is perpetually renewed as long as it is supplied with water.
First of all, it is necessary to find surface water that continuously flows on a sufficiently steep slope (about 10% minimum). If it's a dam or lake, make sure that there are positions below.
To evaluate a site, 4 parameters have to be estimated (as shown on the scheme) :
Concerning the water flow, it it not necessary to be really precise, an average value would be enough to size the system. Several techniques are available, depending on your material and time : see Water flow estimation"
The lift height corresponds to the height difference between the pump height and the water reservoir. Concretely you should decide where you want the water to arrive, and measure the height difference between this point and the water source (in average). This measure will be precised later in the process. Slope measuring can be done with this website https://www.geoportail.gouv.fr/carte : Place GPS coordinates on the map, and use the function "asymetric profile". This correspond to a curve showing the elevation depending on the distance (in m).
The driving line lenght and the fall height are directly related to the river or lake slope. In this case as well, it would be interesting to establish an asymetric profile in order to take distances and elevation gradients into account.
Once the parameters of the site are identified, we will size the pump in order to retrieve the needed flow and a minimal installation coast (the smaller the pump is, the cheaper it will be).
Determine L, H and h:
General Formula: q=((h*Q)/(h + H))0.70
Where 0.70 is the pump efficiency and Q the arrival flow.
Concretely, you will need:
You can also use a fall diagram as shown on the picture to determine H and h.
Sizing of the pump:
To size the pump itself, you have to chose the needed arrival flow. One of the easiest ways to do that is to use the provided table, that gives the final pipe size according to the source flow, the elevation ratio h/H and the final flow.
Using the table, you can proceed as follows:
- Choose the final flow, corresponding to you water needs
- Find the corresponding number in the table according to the elevation ratios of your site
- Do not hesitate to oversize the system in case of doubt
- Verify that you water flow is higher than indicated in the table
- On the same table line, you can read the relevant pump sizing for you situation
You obtain the battery pipe (or driving line) diameter D, which is the same for all other components of the pump.For example: 26x34 to an internal diamter of 26mm and an external diameter of 34mm
All pump components will therefore be of the same dimension, except for the outlet pipe (or delivery pipe) whose diameter D' will be half of the driving line D. D'=D/2
When building a ram pump, 2 different configurations exist that will play a role on the pump efficiency. They concern positions of the primary valve, the internal valve and the air chamber.
Repartition assembly (image 1):
In this case, the primary valve is before the air chamber. This position can make the pump look rather flat, as shown in the first picture of this page. Some sources state that this system can reach 20% higher performance than the other, but we have not been able to prove it yet.
In butting assembly (image 2):
We will describe this system in the tutorial, as it is more widely used. The pump will look more vertical.
To disassemble the extinguisher, you should unscrew the mouthpiece with a wrench and take out the CO2 cartridge it contains.
Then, take out the plastic pipe and the lance.
The outer part is normalised 20x27 and will be screwed to the pump.
To obtain a functional air chamber, you should also empty it from the powder and clean the inside of the extinguisher.
The lance hole should be stuck with something that resists pressure ! If you don' find a lid, you can weld a round metallic part on it.
First technique using a strainer (image 1):
This version is the sturdiest, but will be a bit harder to build
Firstly, disassemble the strainer using a claw clamp.
One the valve is recovered, drill a hole is the center with a 4mm drill. You might ask a turner in his workshop.
Tap at 5mm.
Drill a 6 or 7 mm hole at the top center of the strainer.
Insert the rod in the 5mm hole, with a bit of thread lock.
Second technique using a non-return valve (image 4):
This technique is less sturdy but more accessible because this kind of valve in plastic can be found in most shops.
To open the anti-return valve:
-Place male fittings on each side on the valve to avoid damaging it during the operation
-Distinguish a very thin line that separates two parts of the valve
-Heat at the level of this line using a blowtorch, in order to melt the glue on the inside (be careful not to heat to much).
-Unscrew the valve (using a claw clamp and a vice for example)
Then, remove the plastic flap inside and replace it by a washer, nuts and a threaded rod. (as shown on the 4th image).
Before assembling the system, cover the threads in teflon or any other way of ensuring its sealing.
This video explains the teflon coating.
Then assembly the pump according to this scheme.
To choose a support, you should take into account the system size, in particular the air chamber size, because it may unbalance the whole. The base can be made of wood or metal but for pumps that will be used for a long time, the ideal is to lay a concrete slab.
Cut irons depending on the required length.
Build 2 or 3 pieces in an arc shape using the nails method (the arc diameter should be of the fittings size).
Pierce the arc pieces and the base at the good spots in order to obtain a good clamping but not excessive (it would damage the pipes).
Fix the the pump on the base with the arc pieces using threaded rods and wing nuts.
Firstly, place the ram pump in a flat and even spot, using a bubble level if necessary. Install then the driving pipe and the delivery pipe and plug them (don't forget the teflon for sealing).
At the beggining the pump is empty from water and all valves are closed. Open a little the delivery tap (leading to the tank) and then open fully the water inlet valve (coming from the drive pipe). Water will then push the primary valve and activate the system.
If doesn't work properly, you may activate it manually several times in order to have enough conter pressure in the delivery pipe. If the washers are to heavy, or if the valves' trajectory is not adapted, if may still not work properly. This model allows you to make adjustements by moving the first nut and the number of washers. This settings will also impact the quantity of water in the delivery pipe, compared to the waste water.
You will have to drain regularly the pump. Indeed, there must always be air under pressure in the chamber (pressure is given bu the water push). This air will empty progressively. To fix this, you will have to close both taps (drive and delivery taps), open the drain tap and reactivate the system as shown before.
As all the work of the Low-tech Lab, this tutorial is participative, do not hesitate to add the modifications which seem important to you, and to share your achievements in comments.
This technology was documented during a stopover of the Sea Nomad in the Philippines, on the island of Negros. The NGO "Alternative Indigenous Development Foundation (AIFDI)", based in the city of Bacolod since 1991, helps more than 160 rural communities meet their water needs by installing hydraulic rams throughout the archipelago. The ram pump presented in this tutorial is a different version from the one used by the AIFDI because it is more accessible.
Thanks to Alizée and Yoann from the project Chemins de Faire for the pictures and feedbacks of experience.
The following pages are in french: