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(boiler)</span></h1> <div class="tagline"></div> </div> <ul id="p-associated-pages" class="minerva__tab-container"> <li class="minerva__tab selected mw-list-item"> <a class="minerva__tab-text" href="/wiki/Draft_(boiler)" rel="" data-event-name="tabs.main">Article</a> </li> <li class="minerva__tab mw-list-item"> <a class="minerva__tab-text" href="/wiki/Talk:Draft_(boiler)" rel="discussion" data-event-name="tabs.talk">Talk</a> </li> </ul> <nav class="page-actions-menu"> <ul id="p-views" class="page-actions-menu__list"> <li id="language-selector" class="page-actions-menu__list-item"> <a role="button" href="#p-lang" data-mw="interface" data-event-name="menu.languages" title="Language" class="cdx-button cdx-button--size-large cdx-button--fake-button cdx-button--fake-button--enabled cdx-button--icon-only cdx-button--weight-quiet language-selector"> <span class="minerva-icon minerva-icon--language"></span> <span>Language</span> </a> </li> <li id="page-actions-watch" 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href="/w/index.php?title=Forced_draught&redirect=no" class="mw-redirect" title="Forced draught">Forced draught</a>)</span></div> </div> <div id="bodyContent" class="content"> <div id="mw-content-text" class="mw-body-content"><script>function mfTempOpenSection(id){var block=document.getElementById("mf-section-"+id);block.className+=" open-block";block.previousSibling.className+=" open-block";}</script><div class="mw-content-ltr mw-parser-output" lang="en" dir="ltr"><section class="mf-section-0" id="mf-section-0"> <p>In a water <a href="/wiki/Boiler" title="Boiler">boiler</a>, <b>draft</b> is the difference between atmospheric pressure and the pressure existing in the furnace or flue gas passage.<sup id="cite_ref-1" class="reference"><a href="#cite_note-1"><span class="cite-bracket">[</span>1<span class="cite-bracket">]</span></a></sup> Draft can also be referred to as the difference in pressure in the combustion chamber area which results in the motion of the flue gases and the air flow.<sup id="cite_ref-bab_2-0" class="reference"><a href="#cite_note-bab-2"><span class="cite-bracket">[</span>2<span class="cite-bracket">]</span></a></sup> </p> <div id="toc" class="toc" role="navigation" aria-labelledby="mw-toc-heading"><input type="checkbox" role="button" id="toctogglecheckbox" class="toctogglecheckbox" style="display:none"><div class="toctitle" lang="en" dir="ltr"><h2 id="mw-toc-heading">Contents</h2><span class="toctogglespan"><label class="toctogglelabel" for="toctogglecheckbox"></label></span></div> <ul> <li class="toclevel-1 tocsection-1"><a href="#Types_of_draft"><span class="tocnumber">1</span> <span class="toctext">Types of draft</span></a></li> <li class="toclevel-1 tocsection-2"><a href="#Importance/significance"><span class="tocnumber">2</span> <span class="toctext">Importance/significance</span></a></li> <li class="toclevel-1 tocsection-3"><a href="#Drafting_in_steam_locomotives"><span class="tocnumber">3</span> <span class="toctext">Drafting in steam locomotives</span></a></li> <li class="toclevel-1 tocsection-4"><a href="#See_also"><span class="tocnumber">4</span> <span class="toctext">See also</span></a></li> <li class="toclevel-1 tocsection-5"><a href="#References"><span class="tocnumber">5</span> <span class="toctext">References</span></a></li> </ul> </div> </section><div class="mw-heading mw-heading2 section-heading" onclick="mfTempOpenSection(1)"><span class="indicator mf-icon mf-icon-expand mf-icon--small"></span><h2 id="Types_of_draft">Types of draft</h2><span class="mw-editsection"> <a role="button" href="/w/index.php?title=Draft_(boiler)&action=edit&section=1" title="Edit section: Types of draft" class="cdx-button cdx-button--size-large cdx-button--fake-button cdx-button--fake-button--enabled cdx-button--icon-only cdx-button--weight-quiet "> <span class="minerva-icon minerva-icon--edit"></span> <span>edit</span> </a> </span> </div><section class="mf-section-1 collapsible-block" id="mf-section-1"> <p>Drafts are produced by the rising combustion gases in the stack, flue, or by mechanical means. For example, a boiler can be put into four categories: natural, induced, balanced, and forced. </p> <ul><li>Natural draft: When air or flue gases flow due to the difference in density of the hot flue gases and cooler ambient gases. The difference in density creates a pressure differential that moves the hotter flue gases into the cooler surroundings.<sup id="cite_ref-bab_2-1" class="reference"><a href="#cite_note-bab-2"><span class="cite-bracket">[</span>2<span class="cite-bracket">]</span></a></sup></li> <li>Forced draft: When air or flue gases are maintained above atmospheric pressure. Normally it is done with the help of a forced draft fan.<sup id="cite_ref-bab_2-2" class="reference"><a href="#cite_note-bab-2"><span class="cite-bracket">[</span>2<span class="cite-bracket">]</span></a></sup></li> <li>Induced draft: When air or flue gases flow under the effect of a gradually decreasing pressure below atmospheric pressure. In this case, the system is said to operate under induced draft. The stacks (or chimneys) provide sufficient natural draft to meet the low draft loss needs. In order to meet higher pressure differentials, the stacks must simultaneously operate with draft fans.<sup id="cite_ref-bab_2-3" class="reference"><a href="#cite_note-bab-2"><span class="cite-bracket">[</span>2<span class="cite-bracket">]</span></a></sup></li> <li>Balanced draft: When the static pressure is equal to the atmospheric pressure, the system is referred to as balanced draft. Draft is said to be zero in this system.<sup id="cite_ref-bab_2-4" class="reference"><a href="#cite_note-bab-2"><span class="cite-bracket">[</span>2<span class="cite-bracket">]</span></a></sup></li></ul> </section><div class="mw-heading mw-heading2 section-heading" onclick="mfTempOpenSection(2)"><span class="indicator mf-icon mf-icon-expand mf-icon--small"></span><h2 id="Importance/significance"><span id="Importance.2Fsignificance"></span>Importance/significance</h2><span class="mw-editsection"> <a role="button" href="/w/index.php?title=Draft_(boiler)&action=edit&section=2" title="Edit section: Importance/significance" class="cdx-button cdx-button--size-large cdx-button--fake-button cdx-button--fake-button--enabled cdx-button--icon-only cdx-button--weight-quiet "> <span class="minerva-icon minerva-icon--edit"></span> <span>edit</span> </a> </span> </div><section class="mf-section-2 collapsible-block" id="mf-section-2"> <p>For the proper and the optimized heat transfer from the flue gases to the boiler tubes draft holds a relatively high amount of significance. The combustion rate of the flue gases and the amount of heat transfer to the boiler are both dependent on the movement and motion of the flue gases. A boiler equipped with a combustion chamber which has a strong current of air (draft) through the fuel bed will increase the rate of combustion (which is the efficient utilization of fuel with minimum waste of unused fuel). The stronger movement will also increase the heat transfer rate from the flue gases to the boiler (which improves efficiency and circulation).<sup id="cite_ref-3" class="reference"><a href="#cite_note-3"><span class="cite-bracket">[</span>3<span class="cite-bracket">]</span></a></sup> </p> </section><div class="mw-heading mw-heading2 section-heading" onclick="mfTempOpenSection(3)"><span class="indicator mf-icon mf-icon-expand mf-icon--small"></span><h2 id="Drafting_in_steam_locomotives">Drafting in steam locomotives</h2><span class="mw-editsection"> <a role="button" href="/w/index.php?title=Draft_(boiler)&action=edit&section=3" title="Edit section: Drafting in steam locomotives" class="cdx-button cdx-button--size-large cdx-button--fake-button cdx-button--fake-button--enabled cdx-button--icon-only cdx-button--weight-quiet "> <span class="minerva-icon minerva-icon--edit"></span> <span>edit</span> </a> </span> </div><section class="mf-section-3 collapsible-block" id="mf-section-3"> <p>Since the stack of a <a href="/wiki/Steam_locomotive" title="Steam locomotive">locomotive</a> is too short to provide natural draft, during normal running forced draft is achieved by directing the exhaust steam from the cylinders through a cone ("<a href="/wiki/Blastpipe" title="Blastpipe">blast pipe</a>") upwards and into a skirt at the bottom of the stack. When the locomotive is stationary or in a restricted space "live" steam from the boiler is directed through an annular ring surrounding the blast pipe to produce the same effect. </p> </section><div class="mw-heading mw-heading2 section-heading" onclick="mfTempOpenSection(4)"><span class="indicator mf-icon mf-icon-expand mf-icon--small"></span><h2 id="See_also">See also</h2><span class="mw-editsection"> <a role="button" href="/w/index.php?title=Draft_(boiler)&action=edit&section=4" title="Edit section: See also" class="cdx-button cdx-button--size-large cdx-button--fake-button cdx-button--fake-button--enabled cdx-button--icon-only cdx-button--weight-quiet "> <span class="minerva-icon minerva-icon--edit"></span> <span>edit</span> </a> </span> </div><section class="mf-section-4 collapsible-block" id="mf-section-4"> <ul><li><a href="/wiki/Cooling_tower_system" class="mw-redirect" title="Cooling tower system">Cooling tower system</a></li> <li><a href="/wiki/Stack_effect" title="Stack effect">Stack effect</a></li> <li><a href="/wiki/Boiler#Controlling_draught" title="Boiler">Controlling draught</a></li></ul> </section><div class="mw-heading mw-heading2 section-heading" onclick="mfTempOpenSection(5)"><span class="indicator mf-icon mf-icon-expand mf-icon--small"></span><h2 id="References">References</h2><span class="mw-editsection"> <a role="button" href="/w/index.php?title=Draft_(boiler)&action=edit&section=5" title="Edit section: References" class="cdx-button cdx-button--size-large cdx-button--fake-button cdx-button--fake-button--enabled cdx-button--icon-only cdx-button--weight-quiet "> <span class="minerva-icon minerva-icon--edit"></span> <span>edit</span> </a> </span> </div><section class="mf-section-5 collapsible-block" id="mf-section-5"> <style data-mw-deduplicate="TemplateStyles:r1239543626">.mw-parser-output .reflist{margin-bottom:0.5em;list-style-type:decimal}@media screen{.mw-parser-output .reflist{font-size:90%}}.mw-parser-output .reflist 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a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-limited a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-registration a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-subscription a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .cs1-ws-icon a{background-size:contain;padding:0 1em 0 0}.mw-parser-output .cs1-code{color:inherit;background:inherit;border:none;padding:inherit}.mw-parser-output .cs1-hidden-error{display:none;color:var(--color-error,#d33)}.mw-parser-output .cs1-visible-error{color:var(--color-error,#d33)}.mw-parser-output .cs1-maint{display:none;color:#085;margin-left:0.3em}.mw-parser-output .cs1-kern-left{padding-left:0.2em}.mw-parser-output .cs1-kern-right{padding-right:0.2em}.mw-parser-output .citation .mw-selflink{font-weight:inherit}@media screen{.mw-parser-output .cs1-format{font-size:95%}html.skin-theme-clientpref-night .mw-parser-output .cs1-maint{color:#18911f}}@media screen and (prefers-color-scheme:dark){html.skin-theme-clientpref-os .mw-parser-output .cs1-maint{color:#18911f}}</style><cite id="CITEREFMcGraw2003" class="citation book cs1">McGraw, Hill (2003). <i>Dictionary of Scientific and Tech Terms</i>. USA: Mc Graw Hill Publications. <a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/9780070452701" title="Special:BookSources/9780070452701"><bdi>9780070452701</bdi></a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=Dictionary+of+Scientific+and+Tech+Terms&rft.place=USA&rft.pub=Mc+Graw+Hill+Publications&rft.date=2003&rft.isbn=9780070452701&rft.aulast=McGraw&rft.aufirst=Hill&rfr_id=info%3Asid%2Fen.wikipedia.org%3ADraft+%28boiler%29" class="Z3988"></span></span> </li> <li id="cite_note-bab-2"><span class="mw-cite-backlink">^ <a href="#cite_ref-bab_2-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-bab_2-1"><sup><i><b>b</b></i></sup></a> <a href="#cite_ref-bab_2-2"><sup><i><b>c</b></i></sup></a> <a href="#cite_ref-bab_2-3"><sup><i><b>d</b></i></sup></a> <a href="#cite_ref-bab_2-4"><sup><i><b>e</b></i></sup></a></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFBabcox_&_Wilcox1975" class="citation book cs1">Babcox & Wilcox (1975). <i>Steam/ its generation and use</i> (38 ed.). USA: The Babcock & Wilcox Company. p. 17-1.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=Steam%2F+its+generation+and+use&rft.place=USA&rft.pages=17-1&rft.edition=38&rft.pub=The+Babcock+%26+Wilcox+Company&rft.date=1975&rft.au=Babcox+%26+Wilcox&rfr_id=info%3Asid%2Fen.wikipedia.org%3ADraft+%28boiler%29" class="Z3988"></span></span> </li> <li id="cite_note-3"><span class="mw-cite-backlink"><b><a href="#cite_ref-3">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFRay1909" class="citation book cs1">Ray, Walter T (1909). <i>The Significance of Drafts in Boiler Practice</i>. Washington: <a href="/wiki/Government_Printing_Office" class="mw-redirect" title="Government Printing Office">Government Printing Office</a>. pp. <span class="nowrap">6–</span>8.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=The+Significance+of+Drafts+in+Boiler+Practice&rft.place=Washington&rft.pages=%3Cspan+class%3D%22nowrap%22%3E6-%3C%2Fspan%3E8&rft.pub=Government+Printing+Office&rft.date=1909&rft.aulast=Ray&rft.aufirst=Walter+T&rfr_id=info%3Asid%2Fen.wikipedia.org%3ADraft+%28boiler%29" class="Z3988"></span></span> </li> </ol></div></div>    </section></div> <noscript><img src="https://login.wikimedia.org/wiki/Special:CentralAutoLogin/start?useformat=mobile&type=1x1&usesul3=0" alt="" width="1" height="1" style="border: none; position: absolute;"></noscript> <div class="printfooter" data-nosnippet="">Retrieved from "<a dir="ltr" href="https://en.wikipedia.org/w/index.php?title=Draft_(boiler)&oldid=1239062799">https://en.wikipedia.org/w/index.php?title=Draft_(boiler)&oldid=1239062799</a>"</div></div> </div> <div class="post-content" id="page-secondary-actions"> </div> </main> <footer class="mw-footer minerva-footer" role="contentinfo"> <a class="last-modified-bar" href="/w/index.php?title=Draft_(boiler)&action=history"> <div class="post-content last-modified-bar__content"> <span class="minerva-icon minerva-icon-size-medium minerva-icon--modified-history"></span> <span class="last-modified-bar__text modified-enhancement" data-user-name="InfoManiac297" data-user-gender="unknown" data-timestamp="1723005697"> <span>Last edited on 7 August 2024, at 04:41</span> </span> <span class="minerva-icon minerva-icon-size-small minerva-icon--expand"></span> </div> </a> <div class="post-content footer-content"> <div id='mw-data-after-content'> <div class="read-more-container"></div> </div> <div id="p-lang"> <h4>Languages</h4> <section> <ul id="p-variants" class="minerva-languages"></ul> <ul class="minerva-languages"><li class="interlanguage-link interwiki-ar mw-list-item"><a href="https://ar.wikipedia.org/wiki/%D8%B3%D8%AD%D8%A8_(%D8%BA%D9%84%D8%A7%D9%8A%D8%A9)" title="سحب (غلاية) – Arabic" lang="ar" hreflang="ar" data-title="سحب (غلاية)" data-language-autonym="العربية" data-language-local-name="Arabic" class="interlanguage-link-target"><span>العربية</span></a></li></ul> </section> </div> <div class="minerva-footer-logo"><img src="/static/images/mobile/copyright/wikipedia-wordmark-en.svg" alt="Wikipedia" width="120" height="18" style="width: 7.5em; 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