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70-696: L42 may refer to: HMS Brocklesby (L42) , an ex-coaster taken up from trade that served in World War I for the British Royal Navy Lee–Enfield L42 , a sniper rifle Mitochondrial ribosomal protein L42 , a human protein Sako Model L42 , a rifle Spanish landing ship Pizarro (L42) an engine in GM's Ecotec engine family a version of

140-704: A German convoy off Dieppe . Eskdale torpedoed and sank a German Sperrbrecher or auxiliary minesweeper, while all of the British ships were damaged, with Brocklesby receiving splinter damage from near misses which killed one of her crew. During February 1943 she sailed for the Mediterranean, carrying out convoy escort duties near Gibraltar and in the Western Mediterranean. In July 1943 Brocklesby took part in Operation Husky ,

210-485: A damaged downcomer tube plugged. The mud drums were raised above the floor of the furnace on steel girder stools, increasing the furnace volume available for combustion. This feature was intended to encourage the use of oil burning, an innovation on warships around this time. The general appearance of the White-Forster is similar to that of the later Admiralty pattern . Features such as the raised mud drums and

280-516: A greater ratio of tube surface heating area to the tube volume, thus more rapid steaming. These small-tube boilers also became known as "express" boilers . Although not all of these were three-drum designs (notably the Thornycroft ), most were some variation of this. As the tubes of the three-drum are close to vertical (compared to the Babcock & Wilcox ), this encourages strong circulation by

350-471: A hinged rod through, with a brush at the end. For the curved tube designs, often only part of the tube could be reached. Another method was to pass a chain down the tube from above, pulling a brush behind it, although this was unworkable for boilers like the Thornycroft where the tubes first travelled horizontally or upwards. The eventual method was to use 'bullet' brushes that were fired from one drum into

420-414: A large tube heating area into a small volume, but made tube cleaning impractical. The drums were cylindrical, with perpendicular tube entry and external downcomers between them. The White-Forster was of simple construction, with tubes that had only a gentle curvature to them. This was sufficient to allow them to be replaced in-situ, working through the manhole at the end of the large steam drum. Each tube

490-507: A more rounded section, although still asymmetrical rather than fully cylindrical. The circulation in a Yarrow boiler depended on a temperature difference between the inner and outer tube rows of a bank, and particularly upon the rates of boiling. Whilst this is easy to maintain at low powers, a higher pressure Yarrow boiler will tend to have less temperature difference and thus will have less effective circulation. Some later and higher-pressure boilers were fitted with external downcomers, outside

560-529: A number of their larger locomotives, instead of their usual small vertical boiler . These included railcars for the LNER and LMS . Sentinel's best-known use of the Woolnough was for the 'Colombian' articulated locomotives . These were a series of four, metre gauge locomotives of Co-Co wheel arrangement, built in 1934. They ran at the unusually high pressure of 550 psi (3.8 MPa) and each axle

630-459: A single central upwelling flow to above the water level, encouraging steam bubbles to escape and acting as a steam separator before the water re-circulated down the outer-side tubes. In a manner similar to work taking place around the same time on the LMS railway and the development of top feed for steam locomotives , the feedwater was also routed upwards through 'spray pots' and thus passed through

700-405: A speed of 27.5 knots (50.9 km/h; 31.6 mph). The ship's main gun armament was four 4 inch (102 mm) QF Mk XVI dual purpose (anti-ship and anti-aircraft) guns in two twin mounts, with one mount forward and one aft. Additional close-in anti-aircraft armament was provided by a quadruple 2-pounder "pom-pom" mount. The ship was later modified by adding two single Oerlikon 20 mm cannon on

770-403: A steel outer casing, then back within the shorter tube bank. Coiled tube superheaters were placed in the gas flow outside the tubes. The combustion gases thus passed through the tube bank twice , once outwards and then again inwards. A single central chimney exhausted from the centre of the far end, not as usual from outside the tubes. The relative temperature difference between gas passage through

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840-425: A total of 3,744 being used in some boilers. The tubes were arranged in 24 rows to a bank, each requiring a different length of tube, and 78 rows per drum. All tubes were curved to the same radius, facilitating repair and replacement on board, but requiring the tube holes in the drums to be reamed to precise angles on a jig during manufacture. This small tube diameter gave a high heating surface, but probably too much:

910-743: A trials vessel for anti-submarine operations. She was attached to the 2nd Training Squadron, although mainly carried out trials on behalf of the Underwater Detection Establishments at Portland or Gibraltar. In 1953 she took part in the Coronation Review of the Fleet to celebrate the Coronation of Queen Elizabeth II. Systems tested by Brocklesby included the Type 177 low-frequency hull sonar, which later equipped

980-418: A twin 4-inch mount, cutting down the ships' superstructure and adding ballast. These ships were known as Type I Hunts. Later ships in the class had their beam increased, which allowed them to carry the originally intended armament, and were known as Type II Hunts. Brocklesby was 264 feet 3 inches (80.54 m) long between perpendiculars and 280 feet (85.34 m) overall . The ship's beam

1050-783: Is different from Wikidata All article disambiguation pages All disambiguation pages HMS Brocklesby (L42) HMS Brocklesby was a Type I Hunt-class destroyer of the Royal Navy . She served during the Second World War , spending much of the time in the English Channel and Mediterranean, taking part in the Dieppe Raid in 1942, and the Allied landings in Sicily and at Salerno in 1943. After

1120-501: The Leander -class frigates , and the Type 192 Variable Depth Sonar . Brocklesby almost capsized during trials with the Type 192, when the sonar transducer hit a rock when being towed, and Type 192 was rejected in 1960 in favour of the lighter Canadian Type 199 sonar. On 22 June 1963 she was paid off for the last time. Brocklesby was finally sold for scrap on 21 October 1968 and arrived at Faslane for breaking up on 23 October. She

1190-468: The du Temple and Normand were the first to go. A multi-row bank of tubes could provide adequate heating area, without this complexity. Tubes also became straighter, mostly to ease their cleaning. Yarrow had demonstrated that straight tubes did not cause any problems with expansion, but circular drums and perpendicular tube entry were both valuable features for a long service life. Where tubes entered drums at an angle, heating and cooling tended to bend

1260-582: The Chaika L-4 amphibian aircraft [REDACTED] Topics referred to by the same term This disambiguation page lists articles associated with the same title formed as a letter–number combination. If an internal link led you here, you may wish to change the link to point directly to the intended article. Retrieved from " https://en.wikipedia.org/w/index.php?title=L42&oldid=1183423628 " Category : Letter–number combination disambiguation pages Hidden categories: Short description

1330-778: The English Channel . On 20 March 1942 she was escorting a convoy off Trevose Head in Cornwall when the convoy came under attack by German aircraft, with Brocklesby claiming two German aircraft shot down. On 28 March she took part in the St Nazaire Raid . This was an amphibious assault on the port of St Nazaire in France with the objective of destroying the gates of the Normandie dock by ramming them with an explosive-packed destroyer, Campbeltown , and so prevent

1400-600: The Normand boiler was as a development of the Du Temple , with the sharp corners of the tubes replaced by a smooth radiused bend, but still retaining the S shape. The design of the Normand gave a particularly large heating area (tube surface area) in relation to the grate area. The cost of this was a dense nest of tubes, where each of the numerous rows of tubes was bent into a different and complex shape. Tube ends entered

1470-404: The thermosyphon effect, further encouraging steaming. The development of the three-drum pattern was generally one of simplification, rather than increasing complexity or sophistication. Even the first boilers packed a large heating area into a compact volume, their difficulty was in manufacturing and particularly for their maintenance on-board ship. The convoluted tubes of early designs such as

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1540-447: The "three-drum" design is the arrangement of a steam drum above two water drums , in a triangular layout. Water tubes fill in the two sides of this triangle between the drums, and the furnace is in the centre. The whole assembly is then enclosed in a casing, leading to the exhaust flue . Firing can be by either coal or oil. Many coal-fired boilers used multiple firedoors and teams of stokers , often from both ends. Development of

1610-423: The Allied invasion of Sicily, escorting convoys and on 12 July carried Admiral Ramsay and Generals Eisenhower and Montgomery on an inspection of the beachheads. On 4 August 1943 Brocklesby escorted the monitor Roberts when Roberts shelled roads and railway lines near Taormina in an attempt to slow down the evacuation of German forces towards Messina , and on 15 August Brocklesby , together with

1680-425: The Normand, with downcomers and curved tubes that entered cylindrical drums perpendicularly. The Thornycroft boiler is a variant that splits the usual central furnace into two. There are four drums: two main drums vertically in the centre – a steam and a water drum – also two wing drums at the outside edges of the furnace. The design was notable for its early use of the water-wall furnace . The outer bank of tubes

1750-405: The U was heated, there was the expected upward flow of heated water in that arm of the tube. When heat was also applied to the unheated arm, conventional theory predicted that the circulatory flow would slow or stop completely. In practice, the flow actually increased . Provided that there was some asymmetry to the heating, Yarrow's experiment showed that circulation could continue and heating of

1820-671: The Yarrow was the Admiralty three-drum boiler , developed for the Royal Navy between the First and Second World Wars. Much of the design work was conducted at Admiralty Fuel Experimental Station at Haslar and the first boilers were installed in three of the A ;class destroyers of 1927. These boilers established new Royal Navy standard operating conditions for boilers of 300 psi (2.0 MPa) / 600 °F (316 °C). The design

1890-442: The bank. Superheaters were placed inside this gap and hung by hooks from the steam drum. The advantage of placing the superheaters here was that they increased the temperature differential between the inner and outer tubes of the bank, thus encouraging circulation. In the developed form, the boiler had four rows of tubes on the furnace-side of the superheater and thirteen for the outer-side. The first boilers suffered problems with

1960-399: The boiler and are heated, although not strongly, by the exhaust gases. They are formed as several (eight or nine) 4-inch (10 cm) vertical tubes on the centreline of the boiler. They are formed into a shallow S-shape to give a little flexibility against thermal expansion. The small wing drums are connected to the lower central drum alone, by large external pipes outside the rear casing of

2030-477: The boiler. Owing to its early use in the Thornycroft-built destroyer HMS Daring of 1893, this design became known as the 'Daring' boiler. A small single-sided version of this boiler was also produced for launches . The first small version of this also dispensed with the wing drum, the water-wall tubes bending at right angles and passing back to the central water drum, the tubes also forming

2100-419: The bridge wings. Up to 40 depth charges could be carried. The ship had a complement of 146 officers and men. Brocklesby was laid down at Cammell Laird's Birkenhead shipyard on 18 November 1939 and was launched on 30 September 1940. She was completed on 9 April 1941. After commissioning and workup, Brocklesby joined the 15th Destroyer Flotilla based at Portsmouth , escorting coastal convoys in

2170-526: The casing linked these drums, providing a path for the return circulation of cold water. A further development was the Normand-Sigaudy , where two Normand boilers were coupled back-to-back, for use in large ships. This effectively gave a double-ended Normand (as was later common with the Yarrow ) that could be fired from both ends. The Reed boiler was used by Palmers of Jarrow . It was similar to

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2240-410: The cooler downcomer could even increase this flow. The Yarrow boiler could thus dispense with separate external downcomers. Flow was entirely within the heated watertubes, upwards within those closest to the furnace and downwards through those in the outer rows of the bank. The first Yarrow water drums or "troughs" were D-shaped with a flat tubeplate, so as to provide an easy perpendicular mounting for

2310-420: The cylindrical drums perpendicularly, for good sealing. The space needed for all these tubes filled the entire lower half of the steam drum, requiring both a large drum and a separate steam dome from which to collect dry steam. The external boiler casing entered the flue uptake at one end, usually enclosing this dome. The ends of the drums extended outside the casing as hemispherical domes. Cold downcomers outside

2380-636: The dock's use by the German battleship  Tirpitz . Brocklesby , along with sister ships Cleveland , Atherstone and Tynedale covered the return of the boats carrying the raiding force from St Nazaire, claiming a German Junkers Ju 88 bomber shot down. On 19 August 1942 she took part in the Dieppe Raid , providing fire support for the landings on Green Beach and was hit several times by shells from German shore batteries, which temporarily disabled Brocklesby ' s engines causing her to run aground. The damage received took six weeks to repair. On

2450-411: The drums at the rear of the boiler. The Woolnough design was used by Sentinel for their larger railway locomotives. It resembled most other three-drum designs, having almost-straight tubes. Its distinguishing feature was a firebrick wall two-thirds of the way down the furnace. The furnace grate was on the longer side of this, with the combustion gases passing out through the tube bank, along inside

2520-423: The engagement after coming under fire from German coastal artillery. Brocklesby continued to carry out both convoy escort and offensive operations against German shipping and was involved in an inconclusive engagement with an enemy convoy on 1 November 1942. On the night of 11/12 December, Brocklesby , together with the destroyers Albrighton , Eskdale , Vesper , Whitshed and Worcester , attacked

2590-414: The fleet, and were designed with a heavy anti-aircraft armament of six 4-inch anti-aircraft guns and a speed of 29 knots (33 mph; 54 km/h). An error during design, which was only discovered once the first ship of the class Atherstone was built, meant that the ships as designed were dangerously unstable. To restore stability, the first 23 Hunts, including Brocklesby , were modified by removing

2660-423: The furnace floor, are White-Forster features. The first reduces the risk of grooving , the latter is appropriate for oil firing. The du Temple was an early naval water-tube boiler , patented in 1876. It was invented by Félix du Temple in France and was tested in a Royal Navy torpedo gunboat . Water tubes were convoluted, arranged in four rows to a bank, and S-shaped with sharp right angle bends. This packed

2730-605: The grate to support the fire. Later designs, the Thornycroft-Schulz pattern, made the outer wings more important. The number of their tubes was increased, such that they became the majority of the heating surface and the main gas path for the exhaust gases. The wing drums became large enough to permit a man access inside, for cleaning and expanding new tubes into place. The earlier Thornycroft-Marshall design of water-tube boiler used horizontal hairpin water-tubes fitted into sectional headers. It has little relation to

2800-672: The gunboats Aphis and Soemba , shelled targets south of Messina. On 9 September 1943 Brocklesby took part in Operation Avalanche , the Allied landings at Salerno in Italy. In October 1943 she transferred to the Adriatic, where carried out shore bombardment and landing operations in support of partisans in addition to her normal convoy escort and patrol duties. On the night of 22/23 August 1944, Brocklesby engaged enemy motor torpedo boats attacking Ancona , while on

2870-452: The heated flue area. When superheating was adopted, primarily for use with steam turbines after 1900, the first Yarrow boilers placed their superheater coil outside the main tube bank. Later designs became asymmetrical, with the tube bank on one side doubled and a hairpin-tube superheater placed between them. HMS Havock , the lead ship of the Havock class destroyers , was built with

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2940-446: The key features of the design, a three-drum boiler with straight tubes, yet it took ten years of research before the first boiler was supplied for a torpedo boat of 1887. Early water-tube designers had been concerned with the expansion of the boiler's tubes when heated. Efforts were made to permit them to expand freely, particularly so that those closest to the furnace might expand relatively more than those further away. Typically this

3010-447: The night of 13/14 November, she, together with Wheatland , shelled the port of Bar, Montenegro . On 3 December 1944, she took part in the bombardment of a base for explosive motor boats on the island of Mali Lošinj . She remained in the Adriatic throughout the whole of 1944, returning to the UK for duties in the channel during early 1945. In 1945 Brocklesby along with Southdown

3080-563: The night of 13/14 October 1942, the German commerce raider Komet attempted to break out into the Atlantic through the Channel, escorted by torpedo boats and minesweepers. Brocklesby was part of one of two groups deployed to intercept Komet . After Komet was sunk by the motor torpedo boat MTB 326 , part of the other group, Brocklesby engaged Komet ' s escort, before breaking off

3150-481: The other by use of compressed air. Sets of brushes were used, one for each tube, and they were carefully numbered and counted afterwards to ensure that none had been left behind, blocking a tube. Separate downcomers were used by most designs, even after Yarrow's experiments had demonstrated that circulation could still take place amongst the heated tubes alone. Again, the Admiralty boiler (which omitted downcomers)

3220-461: The ratio of surface to volume became excessive and gas flow through the tube banks was affected, giving the boiler furnaces something of a reputation as poor burners. Downcomers were used, either the usual two large pipes, or an unusual but characteristic arrangement of four small 4-inch (10 cm) tubes to each drum. This was a feature intended to improve survivability after damage, when used on-board warships. The boiler could remain in service with

3290-604: The shape of the tubes were an influence. White-Forster boilers were introduced into the Royal Navy from 1906, for light cruisers and torpedo boat destroyers . The Normand boiler was developed by the French Normand shipyard of Le Havre . It was used by the navies of several nations, notably those of France, Russia, Britain and United States. In 1896, the Royal Navy had them installed in twenty-six boats, more than any other water-tube design. Initial design of

3360-440: The short tubes slightly curved away from each other. Entry into the lower water drum was perpendicular, requiring an almost rectangular drum with the tubes entering on separate faces. The mechanical weakness of such a shape was acceptable in this small size, but limited the boiler's potential. The casing was small and only enclosed part of the upper steam drum, leading directly to a funnel. A single inverted tee-shaped downcomer linked

3430-529: The steam flow speed through the superheater to 150 ft/s (45.72 m/s), avoiding the problems of tube distortion and metallurgical failure. New boilers for the Nelson -class battleships and the Kent -class cruisers could achieve a superheat of 200–250 °F (93–121 °C) throughout the operating power range at 250 psi (1.7 MPa). Unlike contemporary American practice, British naval boilers had

3500-475: The steam space as droplets. The cold feedwater was thus heated to the same temperature as the boiler water before mixing with it, avoiding disturbance to the circulation path. Initial superheat performance was disappointing. Superheat at full power was limited deliberately to 100 °F (37.8 °C) so as to avoid reliability problems, which then meant that it was ineffective at low powers. Development work by Babcock & Wilcox resolved this by increasing

3570-408: The superheaters and with poor circulation for the tube rows in the centre of the bank, leading to overheating and tube failure. The circulation problems were addressed by re-arranging the feedwater pipes and by placing baffles inside the steam drum, so as to give a more clearly defined circulation. A circulation augmenter , a steel trough, was placed over the tops of the furnace-side tubes, encouraging

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3640-525: The then current form of locomotive boiler ; its sister ship HMS Hornet with a Yarrow boiler for comparison. The trials were successful and the Yarrow boiler was adopted for naval service, particularly in small ships. In time the Navy would develop its own Admiralty pattern of three-drum boiler. The Mumford boiler was a variety built by the boilermakers Mumford of Colchester , intended for use in smaller boats. The tube banks separated into two groups, with

3710-560: The three-drum boiler began in the late 19th century, with the demand from naval ships that required high power and a compact boiler. The move to water-tube boilers had already begun, with designs such as the Babcock & Wilcox or the Belleville . The three-drum arrangement was lighter and more compact for the same power. The new generation of "small-tube" water-tube boilers used water-tubes of around 2 inches (5 cm) diameter, compared to older designs of 3 or 4 inches. This gave

3780-509: The tube back and forth, leading to leaks. A perpendicular entry was easier to expand the tubes for a reliable seal and to avoid these sideways stresses. It was worth the compromise of the Admiralty boiler 's bent tube ends to keep these two features, and these tubes were still simple enough in shape to clean easily. Some of the first boiler tubes, particularly the du Temple with its sharp corners, could not be cleaned of scale internally. Tubes were later cleaned internally by attempting to pass

3850-542: The tubes, similar to some early designs, but contrary to the crossflow design of later three-drum boilers. The exhaust gas emerged into the heart-shaped space below the upper central drum, exiting to the funnel through the rear wall. The steam drum is circular, with perpendicular tube entry. The tube ends span a considerable circumference of the drum, so that the upper tubes enter above the water level. They are thus ' non-drowned ' tubes. The upper and lower central drums are linked by downcomers. Unusually these are internal to

3920-585: The tubes. The tubeplate was bolted to the trough and could be dismantled for maintenance and tube cleaning. This D shape is not ideal for a pressure drum though, as pressure will tend to distort it into a more circular section. This flexing led to leakage where the water tubes entered the drum; a problem, termed 'wrapperitis', which was shared with the White-Forster . Experience of boiler explosions had shown that sharp internal corners inside boilers were also prone to erosion by grooving . Later boilers used

3990-404: The two sections of the bank led to a circulation current that was upwards through the first, hotter, part of the bank and downwards through the further, less hot, bank. Circulation was also controlled by an internal weir plate within the upper water drum, so as to keep a depth of water above the ends of the hotter tubes, thus avoiding overheating of dry tubes. Sentinel used the Woolnough boiler on

4060-417: The types described here. The Yarrow boiler design is characterised by its use of straight water-tubes, without downcomers. Circulation, both upwards and downwards, occurs within this same tube bank. Alfred Yarrow developed his boiler as a response to other water-tube designs, and his perception in 1877 that Yarrow & Co were lagging behind other shipbuilders. His initial thoughts already defined

4130-484: The war, she was used as a sonar trials ship until 1963, and was sold for scrap in 1968. HMS Brocklesby was ordered from Cammell Laird on 4 September 1939, one of 17 Hunt-class destroyers ordered from various shipbuilders on that date, (including two from Lairds), which followed on from 20 ships ordered earlier in the year. The Hunts were meant to fill the Royal Navy's need for a large number of small destroyer-type vessels capable of both convoy escort and operations with

4200-492: Was 29 feet 0 inches (8.84 m) and draught 7 feet 9 inches (2.36 m). Displacement was 1,000 long tons (1,000  t ) standard and 1,360 long tons (1,380 t) under full load. Two Admiralty boilers raising steam at 300 pounds per square inch (2,100 kPa) and 620 °F (327 °C) fed Parsons single-reduction geared steam turbines that drove two propeller shafts, generating 19,000 shaft horsepower (14,000 kW) at 380 rpm. This gave

4270-414: Was broadly similar to later high-pressure and oil-fired versions of the Yarrow. The waterdrums were cylindrical and downcomers were sometimes, but not always, used. The only major difference was in the tube banks. Rather than straight tubes, each tube was mostly straight, but slightly cranked towards their ends. These were installed in two groups within the bank, so that they formed a gap between them within

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4340-520: Was done by arranging the tubes in large looping curves. These had difficulties in manufacturing and required support in use. Yarrow recognised that the temperature of the water-tubes was held relatively low and was consistent amongst them, provided that they remained full of water and boiling was not allowed to occur within the tubes themselves, i.e. they would remain as drowned tubes . High temperatures and variations only arose when tubes became steam filled, which also disrupted circulation. His conclusion

4410-591: Was driven by a separate steam motor , designed by Abner Doble . The first was supplied to Belgian Railways , the following three were built for the Société National des Chemins de Fer en Colombe of Colombia , but first shipped to Belgium for testing. Most photographs that exist of these locomotives were taken in Belgium. Little is known of their history after arrival in Colombia. A later development of

4480-563: Was sent to Wilhelmshaven to show the flag immediately after the end of the war. She was then converted to an aircraft target training ship, having her armament removed, serving in that duty at Rosyth and Portsmouth before being placed in reserve at Portsmouth in May 1946. She was reduced to Category C, or extended reserve after 1948, where she was not required for operational service but was preserved for future use. Brocklesby went into refit at Devonport between 1951 and 1952, being converted into

4550-411: Was shallow, consisting of only two rows of tubes. These rows were spaced closely, so that the tubes formed a solid wall, without gasflow between them. The inner bank of tubes was similar: the two rows of tubes closest to the furnace formed a similar water wall. These tubes were splayed apart at their base, so as to provide space for gasflow between them. Within the tube bank, gas flow is mostly parallel to

4620-443: Was sufficiently curved to allow it to be extracted through the steam drum, but sufficiently straight that a single tube could be replaced from a tube bank, without requiring other tubes to be removed so as to permit access. This was one of many features of the White-Forster intended to make it reliable in naval service and easy to maintain. These tubes were of particularly small diameter, only 1 inch (2.5 cm) and especially numerous,

4690-406: Was that flow through the water-tubes would be upwards, owing to their heating by the furnace, and that the counterbalancing downward flow would require external unheated downcomers . Alfred Yarrow conducted a famous experiment where he disproved this assumption. A vertical U-shaped tube was arranged so that it could be heated by a series of Bunsen burners on each side. When only one side of

4760-404: Was the culmination of this approach, placing the superheater within the tube bank, so as to encourage the necessary temperature difference. The Admiralty boiler is usually considered to be a direct evolution of the Yarrow, although the White-Forster also had an influence, probably as a result of the large number in service with the Royal Navy . The circular water drums, and their raising above

4830-657: Was the last of the Hunt class in Royal Navy service. Brocklesby was named after the Brocklesby Hunt , and the ship's badge was based on the crest of Lord Yarborough , who was in charge of the Hunt. The ship was adopted by the town of Belper , Derbyshire in 1942, as part of the Warship Week National saving campaign. The ship was awarded the following Battle honours : Three-drum boiler#Admiralty boiler The fundamental characteristic of

4900-546: Was thus that straight water-tubes were acceptable, and these would have obvious advantages for manufacture and cleaning in service. It was already recognised that a water-tube boiler relied on a continuous flow through the water-tubes, and that this must be by a thermosyphon effect rather than requiring an impractical pump. Forced-circulation boilers with pumps, such as the Velox , did not appear for another thirty years and even then they were initially unreliable. The assumption

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