In praise of the humble hydram

The hydraulic ram, or hydram, is an wondrous invention, developed by French inventor Joseph Michel Montgolfier (Wikipedia, en.wikipedia.org/wiki/Hydraulic_ram) in 1796. It came to India in the 19th century and established itself in the hills of Uttarakhand and Himachal as a reliable and cheap means of pumping water up from running streams. This humble cylindrical device works all day, all week, all year, without power or pause and lifts water from valleys floors to the higher terraces where farmers grow crops.

Its simplicity is its beauty. With two moving parts, both valves, is easy to make and maintain. Essentially a hydram uses the kinetic energy of water to drive it up an incline using the basic principles of physics. Let me first describe the mechanics and then my impressions of this technology.

The device has a drive pipe, a waste valve, a connecting pipe, a check (delivery) valve, an air tank and a delivery pipe. The ratio between the diameter of the inlet and delivery pipehydram 02s determines the quantity of water and the height to which it will be pumped. The greater the ratio, the higher the height but the smaller the quantity.  See the diagram (courtesy Akvopedia, http://www.akvo.org/wiki/index.php/File:PrincipleHydraulicRam.jpg) for details of the construction. It is made of mild steel suitably treated to resist corrosion.

Water from a flowing stream is channeled into the drive pipe, inclined at an upwards angle  or 30 or so degrees. These streams are usually perennial and flow rapidly in deep valleys. They are ideal sources of water for hydrams given their volume and incline, that rams water down the drive pipe. The momentum of this water against the waste valve forces it to close with a loud thump that reverberates up and down the valley every second or two.

The water accumulates and pushes open the check valve. It enters the air chamber and compresses the air. The check valve closes, the air expands and pushes the water up the delivery pipe. In the meantime, water in the drive pipe builds up momentum to force the waste valve shut again. So the cycle continues. Water flows out of the deliver pipe considerably higher than the location of the hydram. (Figure below)

hydram 01The valves wear out and need replacement after a few months, faster if the water is muddy. They are simple to fix, being rubber rings mounted on a steel disc. The rubber in most remote locations is from a tube that is cut to shape and screwed onto the disc. This simplicity makes it possible to make and repair them practically anywhere, and the main structure lasts for years.

The other main problem is the air chamber. The air gradually dissolves in water, though in well-aerated hill streams this is not so much of a problem. Over a period of years, its pressure falls and needs to be replenished. This is again not very difficult as commercial air compressors are available fairly easily at tyre repair shops along main roads, and it is a very occasional problem with the apparatus.

I discovered this remarkable water pump during my research for Jalyatra (www.jalyatra.com) my book on India’s traditional water management systems. True, hydrams are not indigenous in the sense they have not been home grown but they are widely used in remote areas in the hills and in my mind, that is qualification to be indigenous. They are also made here now.

Ramesh Pahadi, a Sarvodayee from Gopeshwar in Uttarakhand, showed me these devices. We stopped on the highway to Kedarnath at the house of a farmer – he grows fruits and sells their jams and honey. When the car’s engine stopped, I could hear a faint thump-thump from the valley below. It was coming from the vegetation along the stream that flowed in the gorge. Ramesh and the farmer led me down the gorge, on a narrow path in the bright afternoon sun. It was warm in the upper reaches of the gorge but became chilly once we reached the bottom. A long steep climb to see the hydram.

There, half under water at the end of a long concrete channel, connected to an inlet pipe, were two cylindrical hydrams thumping away in unison. The blue cylinders looked like air compressors on their ends. From the channel, the pipe carried the stream’s cold clear water into the cylinder, and an outlet pipe carried it up the gorge to the terraces where the farmer grew his fruits. He had spent a lot of money developing his own irrigation system. The pipe emptied into the start of a concrete channel that zig-zagged down the valley watering plants as it went. He could have used drip irrigation instead and maximized his area. Excess water from his acreage flowed downstream to the next farmer.

The farmer had asked the irrigation department to instal the hydrams and paid part of the cost. The government’s subsidy for minor irrigation projects paid the rest. The irrigation engineer fixes them when the break down. A couple of farmers benefit from the Hydrams and they have an assured source of water. When one breaks down, the other keeps running till the engineer comes and fixes it. There are people in the local panchayat who can also fix the hydrams, but its not great business as there are only a few streams in the area suitable for installing them.

What puzzles me is these have not caught on. They are simple devices and can be made locally, just the way people make air compressors. You need wrought iron pipes for the input and delivery ends, and the tank of an air compressor. The valves are metal flaps, with hinges welded to the inside of the pipe, and covered with rubber. The cylinder needs to have some sort of inlet for topping up compressed air every once in a while. These are incredibly useful in any hilly terrain, such as I have seen in the Sahyadris. Streams abound, but farmers do not use hydrams preferring electric pumps instead. A simple transfer of technology would serve hundreds of them.

Hydrams can also be used for rural water supply as they run without power – they can cheaply boost water from a stream uphill for treatment and distribution. Most of these streams are contaminated with animal and human shit and the water would need chlorination, a cheap way to treat it, before drinking. The catch is they need a head of water to work, so are no good in the plains. But anywhere there is a head of water, a hydram can lift water to an overhead tank for distribution.

I hope this apparatus finds some takers among the self-proclaimed Indian rajas of technology in the IITs. If they can simplify its manufacture and improve the design it can be used much more extensively. Given the simplicity of design, all that is needed is a simple way to make them.

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