{"id":21968,"date":"2025-10-28T10:25:16","date_gmt":"2025-10-28T09:25:16","guid":{"rendered":"https:\/\/mag.ebmpapst.com\/en\/?p=21968"},"modified":"2025-11-04T11:56:23","modified_gmt":"2025-11-04T10:56:23","slug":"the-formula-for-the-combustion-air-ratio-in-the-electronic-pneumatic-system","status":"publish","type":"post","link":"https:\/\/mag.ebmpapst.com\/en\/industries\/heating\/the-formula-for-the-combustion-air-ratio-in-the-electronic-pneumatic-system_21968\/","title":{"rendered":"The formula for the combus\u00adtion air ratio in the elec\u00adtronic-pneu\u00admatic system"},"content":{"rendered":"\n

The mechan\u00adical-pneu\u00admatic ratio control system has estab\u00adlished itself as a reli\u00adable prin\u00adciple for control\u00adling the mixture in gas condensing boilers: A blower draws in ambient air via a venturi, and a vacuum is created that opens the gas valve and draws in the fuel. The air\/fuel ratio (\u03bb) is consid\u00adered ideal at \u03bb\u2005\u2005=\u2005\u20051.3 and is calcu\u00adlated as the quotient from the volu\u00admetric flow (VFuel\u2005<\/sub>) of the fuel and air (VAir\u2005<\/sub>). <\/p>\n\n\n\n

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ebm-papst in heating tech\u00adnology<\/h3>\n\n\n\n

Whether effi\u00adcient compo\u00adnents or complete, perfectly coor\u00addi\u00adnated systems \u2013 enjoy the bene\u00adfits of our estab\u00adlished and constantly updated tech\u00adnology.<\/p>\n\n\n\n

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Learn more <\/i><\/a><\/div>\n<\/div>\n<\/div><\/div>\n\n\n
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Fabian Tauben\u00adthaler, Devel\u00adope\u00adment Engi\u00adneer (Photo | ebm-papst)<\/figcaption><\/figure>\n<\/div>\n\n\n

The volu\u00admetric flow indi\u00adcates the quan\u00adtity of fluid, i.e., gas or air, flowing through a defined surface area over a certain period of time. For air, the surface area in a condensing boiler is deter\u00admined by the venturi. In the case of gas, it is deter\u00admined by the main throttle. Both compo\u00adnents act as a resistor in the sense of fluid mechanics, which results in a pres\u00adsure differ\u00adence (\u0394P) between the inlet and outlet. <\/p>\n\n\n\n

Together with the surface area (A), the coef\u00adfi\u00adcient of resis\u00adtance (\u03b6) and the density (\u03c1) of the medium, this signif\u00adi\u00adcantly influ\u00adences how high the volu\u00admetric flow is. This rela\u00adtion\u00adship was described back in the 18th century by \u00adDaniel Bernoulli, whose equa\u00adtion forms the theo\u00adret\u00adical basis for calcu\u00adlating the volu\u00admetric flow. It can be found in the numer\u00adator and the denom\u00adi\u00adnator of the formula shown here.<\/p>\n\n\n\n

As the geom\u00adetry and, there\u00adfore, the surface area of the main throttle and venturi are fixed, the only vari\u00adable para\u00admeter left is the pres\u00adsure differ\u00adence. For air, this stems from the atmos\u00adpheric pres\u00adsure (p1\u2005<\/sub>) and the venturi pres\u00adsure (p4\u2005<\/sub>), which is depen\u00addent on the blower. For gas, it is the differ\u00adence stem\u00adming from venturi pres\u00adsure (p4\u2005<\/sub>) and the pres\u00adsure at the outlet of the gas valve\u2005(p2\u2005<\/sub>), which comprises the atmos\u00adpheric pres\u00adsure (p1\u2005<\/sub>) and what is known as the offset pres\u00adsure. In a mechan\u00adical-pneu\u00admatic ratio control system, the offset pres\u00adsure is set once as a fixed setting when the system is commis\u00adsioned. <\/p>\n\n\n\n

The prin\u00adciple of mechan\u00adical-pneu\u00admatic inter\u00adcon\u00adnec\u00adtion has become estab\u00adlished for mixture control in gas condensing boilers. (Image | ebm-papst) <\/figcaption><\/figure>\n\n\n\n

This is not a problem as long as the mixing ratio does not need to be changed during oper\u00ada\u00adtion. An elec\u00adtronic gas valve makes the system more flex\u00adible: It enables the offset pres\u00adsure to be controlled via soft\u00adware and, there\u00adfore, the gas volu\u00admetric flow to be actively controlled. This plays an impor\u00adtant role when using pure hydrogen as the fuel, for example. As it is highly reac\u00adtive, the gas content can be reduced for a brief moment during the igni\u00adtion in order to prevent issues like flash\u00adback. In addi\u00adtion, the more precise control over the air ratio enables a higher modu\u00adla\u00adtion level, and the oper\u00ada\u00adtion of the condensing boiler can be adapted more accu\u00adrately in line with the actual heat demand.\u2002<\/p>\n","protected":false},"excerpt":{"rendered":"

The mechan\u00adical-pneu\u00ad\u00admatic ratio control system has estab\u00adlished itself as a reli\u00adable prin\u00adciple for control\u00adling the mixture in gas condensing boilers: A blower draws in ambient air via a venturi, and a vacuum is created that opens the gas valve and draws in the fuel. The air\/fuel ratio (\u03bb) is consid\u00adered ideal at \u03bb\u2005\u2005=\u2005\u20051.3 and is [\u2026]<\/p>\n","protected":false},"author":42,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"wp_typography_post_enhancements_disabled":false,"footnotes":""},"categories":[8],"tags":[],"class_list":["post-21968","post","type-post","status-publish","format-standard","hentry","category-heating"],"acf":[],"_links":{"self":[{"href":"https:\/\/mag.ebmpapst.com\/en\/wp-json\/wp\/v2\/posts\/21968","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/mag.ebmpapst.com\/en\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/mag.ebmpapst.com\/en\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/mag.ebmpapst.com\/en\/wp-json\/wp\/v2\/users\/42"}],"replies":[{"embeddable":true,"href":"https:\/\/mag.ebmpapst.com\/en\/wp-json\/wp\/v2\/comments?post=21968"}],"version-history":[{"count":13,"href":"https:\/\/mag.ebmpapst.com\/en\/wp-json\/wp\/v2\/posts\/21968\/revisions"}],"predecessor-version":[{"id":22241,"href":"https:\/\/mag.ebmpapst.com\/en\/wp-json\/wp\/v2\/posts\/21968\/revisions\/22241"}],"wp:attachment":[{"href":"https:\/\/mag.ebmpapst.com\/en\/wp-json\/wp\/v2\/media?parent=21968"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/mag.ebmpapst.com\/en\/wp-json\/wp\/v2\/categories?post=21968"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/mag.ebmpapst.com\/en\/wp-json\/wp\/v2\/tags?post=21968"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}