I had my first experience with a ramp pump way before I understood what it was or how it worked. My hometown Alresford (the ford over the river Arle) has several walks “along the river” as we used to say. One path follows a stream on the left, and on the other side of the stream was (when I was very young) what I now know was a ram pump – it looked a bit like a gas cylinder. This device would make an audible “thump” every so often that, of course, intrigued me as a child. I recently asked my older sister, who would typically have been with me on these walks, if she remembered this device but she has no recollection. Perhaps this says something about the fairer sex. Sadly the pump has long since been removed. I think the picture below shows the location.
A little further along this path and on the right was a subterranean chamber with steps leading down and a metal door at the bottom. This chamber is still there today although seriously grown over by tree and ivy, see recent picture below. It is my belief that another ram pump was inside this chamber. One or perhaps both may have supplied water to the nearby Old Alresford House.
These two locations are approximately at the magenta squares in the map below.
The ram pump requires no external power – in operation it uses the power from the flow of a relatively large volume of water with a small head (perhaps only a few inches) into a small amount of water with a large head (hundreds of feet). It is thus ideally suited to pumping water from a river to a building on a hill. The way it works is gloriously simple.
I made my own ram pump accidentally a few years back. I live in a large house and I was installing a hot-water-cylinder (HWC) to serve a converted outhouse. The water supply came from an open cold-water-storage (CWS) tank about 8m higher and possibly as much as 30m distant, via a ¾” polythene pipe. Not being a trained plumber, and moreover having a degree in Physics and the “I know it all” that comes with it, I figured I knew better than convention and thus committed two blunders. Firstly it seems a good idea to fit a non-return valve at the point where the cold water entered the HWC to stop hot water going backwards. Secondly I did not fit an expansion pipe – this was mainly because to do so would have been nigh impossible because the height of the outbuilding was considerably less than the CWS tank in the attic of the main house. In place of an expansion pipe I fitted an expansion vessel (metal globe painted red with a rubber balloon inside with the water inside and pressurised air between the balloon and the outer globe).
Unintentionally I had created a ram pump. When a hot water tap supplied by the HWC was turned on water would flow slowly at first and gradually speed up due to the considerable inertia in the long feed pipe. If the tap was shut off sharply all that inertia had nowhere to go apart from the pressure vessel. The result was that the pressure in the HWC increased, but as it was already close to the maximum operating pressure for a standard domestic HWC (10m of head) the HWC burst!
Ram pump history (quoted from Wikipedia)
“The first self-acting ram pump was invented by the Frenchman Joseph Michel Montgolfier (best known as a co-inventor of the hot air balloon) in 1796 for raising water in his paper mill at Voiron. His friend Matthew Boulton took out a British patent on his behalf in 1797. The sons of Montgolfier obtained an English patent for an improved version in 1816, and this was acquired, together with Whitehurst's design, in 1820 by Josiah Easton, a Somerset-born engineer who had just moved to London.
“Easton's firm, inherited by his son James (1796–1871), grew during the nineteenth century to become one of the more important engineering manufacturers in the United Kingdom, with a large works at Erith, Kent. They specialised in water supply and sewerage systems world-wide, as well as land drainage projects. Eastons had a good business supplying rams for water supply purposes to large country houses, and also to farms and village communities, and a number of their installations still survived as of 2004.
“The firm was eventually closed in 1909, but the ram business was continued by James R Easton. In 1929 it was acquired by Green & Carter of Winchester, Hampshire, who were engaged in the manufacturing and installation of the well-known Vulcan and Vacher Rams.”
Having read this I contacted Green & Carter and was pleased to get a reply from their CEO who claims they have records of all ram pump purchases since 1774. Although he did not find the particular I have alluded to, he did find "a large 8in ram no 12591 which we installed for HN Walford in January 1929". This would appear to be the one mentioned here a mile or so further west and which supplied water to Arlebury House. On my next visit to Alresford I intend to investigate to see if I can find any trace of these pumps.
Here's Green & Carters explanation of how the pump works:
Sadly missing from this diagram is reference to the necessary "sniffer" valve. I love the names engineers make up. Like gusset, hip, dress, skirt, shoe, orifice, master and slave, male and female threads, grease nipple, kiss, etc. The sniffer valve does just what it says - it lets in some air with a "sniff" each cycle, making sure that there is always an air cushion in the dome.
In this age of digital electronics it is easy to forget the really cool inventions of a bygone era some of which we still depend upon, such as the ram pump.
See also Ram pumps revisted and Ram pumps again.
No comments:
Post a Comment