{"id":37949,"date":"2024-01-30T21:23:20","date_gmt":"2024-01-30T21:23:20","guid":{"rendered":"https:\/\/www.alicat.com\/?post_type=article&#038;p=37949"},"modified":"2026-03-12T17:53:07","modified_gmt":"2026-03-12T17:53:07","slug":"was-ist-der-massendurchfluss","status":"publish","type":"support","link":"https:\/\/www.alicat.com\/de\/support\/what-is-mass-flow\/","title":{"rendered":"Was ist Massendurchfluss?"},"content":{"rendered":"\n[et_pb_section fb_built=&#8221;1&#8243; _builder_version=&#8221;4.23.1&#8243; _module_preset=&#8221;default&#8221; global_colors_info=&#8221;{}&#8221; theme_builder_area=&#8221;post_content&#8221;][et_pb_row _builder_version=&#8221;4.23.1&#8243; _module_preset=&#8221;default&#8221; global_colors_info=&#8221;{}&#8221; theme_builder_area=&#8221;post_content&#8221;][et_pb_column type=&#8221;4_4&#8243; _builder_version=&#8221;4.23.1&#8243; _module_preset=&#8221;default&#8221; global_colors_info=&#8221;{}&#8221; theme_builder_area=&#8221;post_content&#8221;][et_pb_heading title=&#8221;What is mass flow?&#8221; _builder_version=&#8221;4.23.1&#8243; _module_preset=&#8221;default&#8221; global_colors_info=&#8221;{}&#8221; theme_builder_area=&#8221;post_content&#8221;][\/et_pb_heading][et_pb_text _builder_version=&#8221;4.27.4&#8243; _module_preset=&#8221;default&#8221; hover_enabled=&#8221;0&#8243; global_colors_info=&#8221;{}&#8221; theme_builder_area=&#8221;post_content&#8221; sticky_enabled=&#8221;0&#8243;]Most Alicat devices measure and control the mass flow rate of a gas. As gas flows through an Alicat, it passes through a flow channel with temperature and pressure sensors. These sensors measure the instantaneous temperature and pressure of the gas stream and use that information in combination with known gas properties to calculate a mass flow rate.\n\nThis mass flow rate is really a volumetric flow rate standardized to a specific set of temperature and pressure conditions.\n<h2>Calculating mass flow using instantaneous temperature and pressure readings<\/h2>\nImagine flowing argon through an Alicat mass flow instrument. The sensors within the flow stream read 23\u00b0C and 20 PSIA, and these values are shown on the screen of the device. These values are not directly used to calculate the mass flow rate, however.\n\nEach Alicat device is loaded with gas tables containing values from 3-dimensional gas properties data. These tables chart NIST-traceable gas compressibility and viscosity data against pressure and temperature across the entire usable range of the mass flow device. The mass flow rate shown on screen is the volumetric flow rate of the gas\u00a0<em>if it was flowing at standard temperature and pressure (STP) conditions.\u00a0<\/em>\n\nThe simple steps are as follows:\n<ol>\n\t<li>The device uses the actual temperature and pressure of the gas to calculate the instantaneous volumetric flow rate.<\/li>\n\t<li>The device uses an algorithm to calculate what the flow rate would be if the gas were at 25\u00b0C and 1 atm.<\/li>\n\t<li>The device outputs a standardized volumetric flow rate, or mass flow rate.<\/li>\n<\/ol>\n<iframe title=\"How a Laminar Flow Differential Pressure Meter Works - Alicat Scientific\" width=\"1080\" height=\"608\" src=\"https:\/\/www.youtube.com\/embed\/Yp7hRo7clUs?feature=oembed&rel=0\"  allow=\"accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture; web-share\" allowfullscreen><\/iframe>\n<h3>STP conditions<\/h3>\nWhether flowing at 23\u00b0C and 20 PSIA, or -10\u00b0C and 56 PSIA, or 42\u00b0C and 14 PSIA\u2026 the mass flow rate shown on screen will always be the same value. All measurements are converted to a standardized volumetric flow rate using STP conditions. The default STP conditions are 25\u00b0C and 1 atm (14.6959 PSIA), however this is adjustable.\n\nGoing back to the example above, a standardized volumetric flow rate will be calculated for argon at 23\u00b0C and 20 PSIA. However, at 25\u00b0C and 1 atm, argon has the following properties:\n<ul>\n\t<li><span style=\"color: #000000;\">Absolute viscosity: 226.23990<\/span><\/li>\n\t<li><span style=\"color: #000000;\">Density: 1.63387<\/span><\/li>\n\t<li><span style=\"color: #000000;\">Compressibility: 0.9993656<\/span><\/li>\n<\/ul>\nNo matter what temperature or pressure you are flowing the argon, the value shown on screen will always be as if the gas was flowing at 25\u00b0C and 1 atm.\n<div class=\"link-with-icons-wrap m-b\"><strong><a href=\"https:\/\/www.alicat.com\/support\/stp-ntp-tutorial\/\">Adjusting STP\/NTP conditions<\/a><\/strong><\/div>\n<h2>Units of mass flow<\/h2>\nBecause mass flow rate is a standardized volumetric flow rate, the units are typically expressed as such. Examples include SLPM (standard liters per minute), SCCM (standard cubic centimeters per minute), and SCFH (standard cubic feet per hour).\n\nThese are volumes per time, not units of mass. However, a mass flow rate can easily be converted to a true mass flow rate using the following equation: True mass flow = (mass flow rate)(gas density at STP or NTP). All you need is the mass flow rate and the gas density.\n\nSome mass flow instruments output a true mass flow measurement directly, such as Coriolis instruments.\n\n<iframe title=\"How a Coriolis Flow Meter Works - Alicat Scientific\" width=\"1080\" height=\"608\" src=\"https:\/\/www.youtube.com\/embed\/h8JbMrNhq-w?feature=oembed&rel=0\"  allow=\"accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture; web-share\" allowfullscreen><\/iframe>\n<h2>When to use mass flow<\/h2>\nA mass flow rate is standardized such that you can confidently flow exact numbers of particles through your system without having to worry about temperature or pressure fluctuations. Mass flow devices are commonly used for applications requiring high accuracy, precision measurement and control of specific amounts of gas.\n\nImagine you need to flow argon through a mass flow controller at exactly 5 SLPM. When you begin flowing, the temperature and pressure of the gas are 23\u00b0C and 20 PSIA. However, someone turns on a furnace nearby and the temperature climbs up to 27\u00b0C. The device will always correct the values to STP conditions,\u00a025\u00b0C and 1 atm, and the exact right amount of particles will be flowed.\n\nMany applications benefit from measuring and controlling mass flow, including bioreactor outgassing, <a href=\"https:\/\/www.alicat.com\/support\/fuel-cell-regulation-and-testing-solutions\/\">fuel cell membrane testing<\/a>, and <a href=\"https:\/\/www.alicat.com\/support\/framergy-case-study\/\">natural gas monitoring<\/a>.\n<div class=\"link-with-icons-wrap m-b\"><strong><a href=\"https:\/\/www.alicat.com\/support\/what-is-the-difference-between-mass-flow-and-volumetric-flow\/\">When to use volumetric flow or mass flow<\/a><\/strong><\/div>\n<h2>Does mass flow rate change with density?<\/h2>\nMass flow rate depends on the density of the gas that is being flowed. For laminar differential pressure devices, it is important to know the exact composition of the gas being flowed so that precise density corrections can be made.\n\nFortunately, Alicat <a href=\"https:\/\/www.alicat.com\/products\/gas-flow\/mass-flow-meter\/laminar-dp-mass-flow-meters\/\">differential pressure meters<\/a> and <a href=\"https:\/\/www.alicat.com\/products\/gas-flow\/mass-flow-controller\/laminar-dp-mass-flow-controllers\/\">differential pressure controllers<\/a> are pre-loaded with <a href=\"https:\/\/www.alicat.com\/documentation\/gas-select-gas-list\/\">98+ gases<\/a> containing gas density information. A bonus of calculating and reporting at standard conditions is that it is fairly easy to <a href=\"https:\/\/www.alicat.com\/support\/correcting-flow-data-after-choosing-the-wrong-gas-in-gas-select\/\">apply correction factors<\/a> to your flow data if you accidentally flow with the wrong gas selected.\n\nTrue mass flow measurements also depend on density. <a href=\"https:\/\/www.alicat.com\/products\/gas-flow\/mass-flow-meter\/gas-low-flow-coriolis-mass-flow-meters\/\">Coriolis mass flow meters<\/a> and <a href=\"https:\/\/www.alicat.com\/products\/gas-flow\/mass-flow-controller\/gas-low-flow-coriolis-controllers\/\">Coriolis mass flow controllers<\/a>, however, do not use known gas properties to calculate flow rates. They are able to measure fluid densities themselves and accurately output true mass flow rates, even when flowing process fluids of unknown composition.[\/et_pb_text][\/et_pb_column][\/et_pb_row][\/et_pb_section]\n","protected":false},"featured_media":46458,"parent":0,"template":"","meta":{"_acf_changed":false,"_et_pb_use_builder":"on","_et_pb_old_content":"","_et_gb_content_width":"1920","content-type":"","_searchwp_excluded":""},"categories":[],"class_list":["post-37949","support","type-support","status-publish","has-post-thumbnail","hentry"],"acf":[],"yoast_head":"<!-- This site is optimized with the Yoast SEO Premium plugin v27.3 (Yoast SEO v27.3) - https:\/\/yoast.com\/product\/yoast-seo-premium-wordpress\/ -->\n<title>What is Mass Flow? - Alicat Scientific<\/title>\n<meta name=\"description\" content=\"Most Alicat devices measure and control the mass flow rate of a gas. As gas flows through an Alicat, it passes through a flow channel with temperature and pressure sensors. These sensors measure the instantaneous temperature and pressure of the gas stream and use that information in combination with known gas properties to calculate a mass flow rate.\" \/>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/www.alicat.com\/de\/unterstutzung\/was-ist-der-massendurchfluss\/\" \/>\n<meta property=\"og:locale\" content=\"de_DE\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"What is Mass Flow?\" \/>\n<meta property=\"og:description\" content=\"Most Alicat devices measure and control the mass flow rate of a gas. As gas flows through an Alicat, it passes through a flow channel with temperature and pressure sensors. These sensors measure the instantaneous temperature and pressure of the gas stream and use that information in combination with known gas properties to calculate a mass flow rate.\" \/>\n<meta property=\"og:url\" content=\"https:\/\/www.alicat.com\/de\/unterstutzung\/was-ist-der-massendurchfluss\/\" \/>\n<meta property=\"og:site_name\" content=\"Alicat Scientific\" \/>\n<meta property=\"article:publisher\" content=\"https:\/\/www.facebook.com\/alicatscientific\/\" \/>\n<meta property=\"article:modified_time\" content=\"2026-03-12T17:53:07+00:00\" \/>\n<meta property=\"og:image\" content=\"https:\/\/www.alicat.com\/wp-content\/uploads\/2026\/01\/featured-alicat.png\" \/>\n\t<meta property=\"og:image:width\" content=\"1200\" \/>\n\t<meta property=\"og:image:height\" content=\"630\" \/>\n\t<meta property=\"og:image:type\" content=\"image\/png\" \/>\n<meta name=\"twitter:card\" content=\"summary_large_image\" \/>\n<meta name=\"twitter:label1\" content=\"Est. reading time\" \/>\n\t<meta name=\"twitter:data1\" content=\"4\u00a0Minuten\" \/>\n<script type=\"application\/ld+json\" class=\"yoast-schema-graph\">{\"@context\":\"https:\\\/\\\/schema.org\",\"@graph\":[{\"@type\":\"WebPage\",\"@id\":\"https:\\\/\\\/www.alicat.com\\\/support\\\/what-is-mass-flow\\\/\",\"url\":\"https:\\\/\\\/www.alicat.com\\\/support\\\/what-is-mass-flow\\\/\",\"name\":\"What is Mass Flow? - Alicat Scientific\",\"isPartOf\":{\"@id\":\"https:\\\/\\\/www.alicat.com\\\/#website\"},\"primaryImageOfPage\":{\"@id\":\"https:\\\/\\\/www.alicat.com\\\/support\\\/what-is-mass-flow\\\/#primaryimage\"},\"image\":{\"@id\":\"https:\\\/\\\/www.alicat.com\\\/support\\\/what-is-mass-flow\\\/#primaryimage\"},\"thumbnailUrl\":\"https:\\\/\\\/www.alicat.com\\\/wp-content\\\/uploads\\\/2026\\\/01\\\/featured-alicat.png\",\"datePublished\":\"2024-01-30T21:23:20+00:00\",\"dateModified\":\"2026-03-12T17:53:07+00:00\",\"description\":\"Most Alicat devices measure and control the mass flow rate of a gas. 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