A vacuum coffee maker brews coffee using two chambers where vapor pressure and gravity produce coffee. This type of coffee maker is known as vac pot, siphon or syphon coffee maker, was invented by Loeff of Berlin in the 1830s; these devices have since been used for more than a century in many parts of the world. Design and composition of the vacuum coffee maker varies; the chamber material is borosilicate glass, metal, or plastic, the filter can be either a glass rod or a screen made of metal, paper, or nylon. The Napier Vacuum Machine, presented in 1840, was an early example of this technique. While vacuum coffee makers were excessively complex for everyday use, they were prized for producing a clear brew, were quite popular until the middle of the twentieth century. Vacuum coffee makers remain popular including Japan and Taiwan; the Bauhaus interpretation of this device can be seen in Gerhard Marcks' Sintrax coffee maker of 1925. A vacuum coffee maker operates as a siphon, where heating and cooling the lower vessel changes the vapor pressure of water in the lower, first pushing the water up into the upper vessel allowing the water to fall back down into the lower vessel.
Concretely, the principle of a vacuum coffee maker is to heat water in the lower vessel of the brewer until expansion forces the contents through a narrow tube into an upper vessel containing coffee grounds. During brewing, a small amount of water and sufficient water vapor remain in the lower vessel and are kept hot enough so the pressure will support the column of water in the siphon; when enough time has elapsed that the coffee has finished brewing, the heat is removed and the pressure in the bottom vessel drops, so the force of gravity and atmospheric pressure push the water down into the lower vessel, through a strainer and away from the grounds, ending brewing. The coffee can be decanted from the lower chamber; the iconic Moka pot coffee maker functions on the same principle but the water is forced up from the bottom chamber through a third middle chamber containing the coffee grounds to the top chamber which has an air gap to prevent the brewed coffee from returning downwards. The prepared coffee is poured off from the top.
Note that siphons work by pushing, it is the changing vapor pressure in the lower vessel, combined with the constant atmospheric pressure in the upper vessel that drive the siphon. When the water cools the pressure in the lower vessel drops as steam condenses into dense water, taking up less volume and hence dropping the pressure; this creates a partial vacuum, causing the atmospheric pressure outside the container to force the liquid back into the lower vessel. An early variation of this principle is called a balance siphon; this implementation has the two chambers arranged side by side on a balance-like device, with a counterweight attached to the heated chamber. Once the vapor has forced the hot water out, the counterweight activates a spring-loaded snuffer which smothers the flame and allows the initial chamber to cool down thus lowering pressure and causing the brewed coffee to seep in. Coffee portal Minto wheel Vac Pot FAQ Vac Pot How-To pdf Siphon Brewer In Operation:Sydney Australia
Keekle Viaduct is a former railway viaduct near Keekle, England. The viaduct is a substantial structure which carried the double-track C&WJR's Cleator Moor West to Siddick Junction via Workington Central main line over the River Keekle, it is situated between the former stations of Keekle Colliers' Platform. Opened in 1879, it consists of seven equal stone arches across the river. Timetabled passenger services over the viaduct ended on 13 April 1931. Goods and mineral trains, with occasional passenger excursions and diversions continued to use the line until it closed on 16 September 1963; the tracks were subsequently lifted. The structure was offered for sale for £1 in 1992, but there was no initial response, as any purchaser would have to maintain and repair it, rather than demolish it and recover the stone. In 2013 satellite imagery showed. Anderson, Paul. Hawkins, Chris. "Dog in the Manger? The Track of the Ironmasters". British Railways Illustrated. Clophill: Irwell Press Ltd. 11. Joy, David. Railways of the Lake Counties.
Clapham, via Lancaster: Dalesman Publishing. ISBN 0 85206 200 1. McGowan Gradon, W.. The Track of the Ironmasters: A History of the Cleator and Workington Junction Railway. Grange-over-Sands: Cumbrian Railways Association. ISBN 0-9540232-2-6. Marshall, John. Forgotten Railways: North West England. Newton Abbot: David & Charles. ISBN 0 7153 8003 6. News, Whitehaven. Peascod, Michael. "Not for £1". Cumbrian Railways. Pinner: Cumbrian Railways Association. 4. ISSN 1466-6812; the line in green via Rail Map Online The viaduct on overlain OS maps surveyed from 1898, via National Library of Scotland The railways of Cumbria, via Cumbrian Railways Association Photos of Cumbrian railways, via Cumbrian Railways Association The railways of Cumbria, via Railways_of_Cumbria Cumbrian Industrial History, via Cumbria Industrial History Society Furness Railtour using many West Cumberland lines 5 September 1954, via sixbellsjunction A video tour-de-force of the region's closed lines, via cumbriafilmarchive The viaduct and Keekle Terrace, via flickr