The pulsometer pump, link to Tai Tam Tuk Reservoirs
Our article, Hong Kong Water Supply – The Tai Tam Tuk Scheme First Section, contains this paragraph, mentioning a pulsometer pump, and the advert shown below for the Pulsometer Engineering Company based in London:
“To establish the nature of the ground, a series of brick wells or shafts were constructed in the shallow waters of Tai Tam bay. Using two barges equipped with boilers, steam winches and derricks were mobilised to support the construction of a brick shaft within the shallow waters. A brick shaft was constructed above a cast iron ring and this was then lowered through the water and sunk into the seabed. By excavating the soft material from inside the shaft, the brick shaft would descend into the sea bed. As the structure descended into the soft soil additional brick layers were added. With an internal size of 1.7m (5’8”) excavation was undertaken by hand or using a grab bucket operated by the steam winches. The wells were kept dry by bailing the water out or using a pulsometer pump driven by the steam from the barge boiler.”
Intrigued I investigated what a pulsometer pump was as shown below.
The Pulsometer steam pump is a pistonless pump which was patented in 1872 by American Charles Henry Hall. In 1875 a British engineer bought the patent rights of the Pulsometer and it was introduced to the market soon thereafter. The invention was inspired by the Savery steam pump invented by Thomas Savery. Around the turn of the century, it was a popular and effective pump for quarry pumping.(1)
Pulsometer A steam operated pump with few moving parts, based on the device invented by Thomas Savery (c.1650-1717) see ‘Miners Friend’. A pulsometer pump comprises a casing divided into two equal chambers with a common steam inlet at the top. A rubber ball is constrained to move sideways at the top of the chambers to cover and uncover the steam entrance to each chamber in turn. A common water inlet is at the bottom of the casing with a non-return valve controlling the way into each chamber. Near the bottom of each chamber is a water outlet which joins a common pump delivery pipe. Steam enters one chamber, the ball closing off the other, and steam pressure forces out water lying in the chamber into the delivery pipe. As the water level falls its lower temperature condenses the steam, causing a partial vacuum which pulls the rubber ball across to the other side, and sucks in a fresh volume of water into the chamber. The steam now enters the second chamber and forces out the water which had been sucked into it by the previous cycle. The sequence then repeats itself automatically. The pulsometer needs priming to start off, and although it is rather extravagant in steam, and can only pump a few feet, its big advantage is its simplicity; it can also handle a certain amount of suspended solids in the water. A pulsometer pump was developed by Hall in 1876.(2)
‘Miners Friend’ name used by Captain Thomas Savery (c1650?-1715) to describe his 1 hp ‘steam engine’ or Pulsometer in a pamphlet he published in 1702. His invention, patented in 1698 (patent mo. 356) was claimed to ‘raise water by the impellent force of fire’. In actual fact, the lift obtained from the device was inadequate for raising water from mines, but several were used where low lifts were needed, such as for supplying buildings with water, and recirculating water to existing waterwheels. Since only primitive boilers were available in those days, only low pressures could be used, although attempts were made to use high pressures with disastrous results. The ‘Miners Friend’ was superseded by Thomas Newcomen’s Atmospheric Engine around 1712, although because Savery’s patent did not expire until 1733 its existence prevented Newcomen from patenting his more successful engine. However, a Savery type engine was still being used in Marshall’s flax factory, Leeds, in 1791 for light pumping work, and one was in use as late as 1820 in Kentish Town, London, for raising water for a waterwheel which drove machinery in an engineering works. It was because of the allusion to the use of fire in the patent that early steam engines were often called fire engines.
- Dictionary of Industrial Archaeology, W. Jones, Sutton Publishing, 2006
This article was first posted on 19th December 2021.
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