based on whether the movement is transmitted by a mechanical part in an alternating or rotating way.<\/p>\n
They quantity of fluid pumped depends of various factors.<\/p>\n
m<\/em>t<\/em><\/sub> : theoretical mass of fluid transferred (depends on the volume of the chamber in which the fluid enters) The final efficiency of fluid mass in delivery will therefore be:<\/p>\n \u03b7v <\/em><\/sub>volumetric efficiency, produced between <\/em>\u03bbv <\/em><\/sub>* <\/em>\u03bbp<\/em><\/sub>.<\/em><\/p>\n Alternating volumetric pumps are usually piston pumps and they can be classified according to the type of piston:<\/p>\n These can be further divided into:<\/p>\n Single effect<\/p><\/div>\n Double effect<\/p><\/div>\n Let’s examine the ideal work cycle of an alternating volumetric pump, without any leaks of any kind inside the pump.<\/p>\n Ideal work cycle:<\/p><\/div>\n Phase 1-2: the fluid is drawn inside the chamber In actual fact the cycle is as follows.<\/p>\n Actual work cycle:<\/p><\/div>\n As can be seen in the figure, the actual cycle differs from the ideal one due to certain effects that cannot be ignored.<\/p>\n In particular:<\/p>\n There are solutions that can limit these effects:<\/p>\n As mentioned earlier, one of the main problems of alternating volumetric pumps is the irregular flow rate. For simplicity’s sake let’s examine an alternating piston pump with a cylindrical shape, with an ordinary crank gear.<\/p>\n The performance of the volumetric flow rate over time will therefore have the shape shown in figure a). Using a pump with various cylinders or a double acting cylinder reduces problems due to the pulsations on a pumping system.<\/p>\n To regulate the volumetric flow rate, compensators are used along the suction and delivery line. Air chambers<\/p><\/div>\n Using the flow rate performance graphs, there are two phases during the piston cycle:<\/p>\n In this way there will be a fairly constant flow rate in the ducts.<\/p>\n This mechanism is accelerated thanks to the gas contained in the compensator that, by compressing and expanding, reduces the pulsation of the fluid flow.<\/p>\n","protected":false},"excerpt":{"rendered":" This type of pump is used for fluids that cannot be significantly compressed. The working fluid is processed by the machine in a control volume that varies over time periodically. The work is exchanged statically with the machine, on moving surfaces. The volumetric pumps may be: alternating; rotatative. based on whether the movement is transmitted by a mechanical part in an alternating or rotating way. They quantity of fluid pumped depends of various factors. mt : theoretical mass of fluid transferred (depends on the volume of the chamber in which the fluid enters) \u03bbv :\u00a0volumetric filling coefficient, given by the relation between the suction fluid mass ma\u00a0\u00a0and theoretical mass\u00a0mt \u03bbp :\u00a0 loss coefficient, given by the relation between fluid mass in delivery\u00a0mm\u00a0and suction mass ma The final efficiency of fluid mass in delivery will therefore be: \u03b7v volumetric efficiency, produced between \u03bbv * \u03bbp. Alternating volumetric pumps are usually piston pumps and they can be classified according to the type of piston: plunger; disc or diaphragm. These can be further divided into: single effect (the complete cycle includes a suction and a delivery); double effect (for each cycle there are, alternating, two suctions and two deliveries). WORK CYCLE Let’s examine…<\/p>\n","protected":false},"author":2,"featured_media":34713,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"mc4wp_mailchimp_campaign":[],"footnotes":""},"categories":[456],"tags":[],"class_list":["post-33968","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-how-does-it-work"],"aioseo_notices":[],"_links":{"self":[{"href":"https:\/\/www.debem.com\/en\/wp-json\/wp\/v2\/posts\/33968","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.debem.com\/en\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.debem.com\/en\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.debem.com\/en\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.debem.com\/en\/wp-json\/wp\/v2\/comments?post=33968"}],"version-history":[{"count":0,"href":"https:\/\/www.debem.com\/en\/wp-json\/wp\/v2\/posts\/33968\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.debem.com\/en\/wp-json\/wp\/v2\/media\/34713"}],"wp:attachment":[{"href":"https:\/\/www.debem.com\/en\/wp-json\/wp\/v2\/media?parent=33968"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.debem.com\/en\/wp-json\/wp\/v2\/categories?post=33968"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.debem.com\/en\/wp-json\/wp\/v2\/tags?post=33968"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}
\n\u03bbv<\/em> <\/sub>:\u00a0volumetric filling coefficient, given by the relation between the suction fluid mass m<\/em>a\u00a0\u00a0<\/em><\/sub>and theoretical mass\u00a0m<\/em>t
\n<\/em><\/sub>\u03bbp<\/em> <\/sub>:\u00a0 loss coefficient, given by the relation between fluid mass in delivery\u00a0m<\/em>m<\/em>\u00a0<\/sub>and suction mass m<\/em>a<\/em><\/sub><\/p>\n\n
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![\"\"](\"https:\/\/www.debem.com\/wp-content\/uploads\/sites\/3\/2022\/03\/volumetriche1.png\")
![\"\"](\"https:\/\/www.debem.com\/wp-content\/uploads\/sites\/3\/2022\/03\/volumetriche2-300x108.png\")
WORK CYCLE<\/strong><\/h2>\n
![\"\"](\"https:\/\/www.debem.com\/wp-content\/uploads\/sites\/3\/2022\/03\/volumetriche4.png\")
\nPhase 2-3: there is an instantaneous compression
\nPhase 3-4: the fluid is pushed through the delivery duct
\nPhase 4-1: instantaneous expansion (decompression phase)<\/p>\n![\"\"](\"https:\/\/www.debem.com\/wp-content\/uploads\/sites\/3\/2022\/03\/volumetriche5.png\")
\n
\n
FLOATING VOLUME PROBLEM<\/strong><\/h2>\n
\nIn fact, seeing as, in both piston pumps and in diaphragm pumps, the speed at which the mechanical part that provides the thrust varies over time (Vs(t)), the instantaneous volumetric flow rate (Qis<\/sub><\/em>) of the pump will also vary.<\/p>\n![\"\"](\"https:\/\/www.debem.com\/wp-content\/uploads\/sites\/3\/2022\/03\/pompe-volumetriche-alternative.jpg\")
<\/p>\n
\nOne of the simplest solutions to regulate the flow and eliminate the moments when the flow rate drops to zero, is to increase the number of pistons (graph b) and c)), or in the same way, increase the effects of the single piston (graph b), double acting single cylinder pump).<\/p>\n![\"\"](\"https:\/\/www.debem.com\/wp-content\/uploads\/sites\/3\/2022\/03\/volumetriche6.png\")
Flow rate performance for single, twin and three cylinders.<\/p>\nAIR CHAMBERS<\/strong><\/h2>\n
\nThey are half-filled with the working fluid whilst the upper part is filled with gas (often air).<\/p>\n![\"\"](\"https:\/\/www.debem.com\/wp-content\/uploads\/sites\/3\/2022\/03\/volumetriche7.png\")
\n