{"id":51828,"date":"2013-08-04T14:30:00","date_gmt":"2013-08-04T14:30:00","guid":{"rendered":"https:\/\/discover.restek.com\/uncategorized\/to-15-canister-relative-humidity-part-ii-examples-and-calculations\/"},"modified":"2025-12-12T20:26:02","modified_gmt":"2025-12-12T20:26:02","slug":"to-15-canister-relative-humidity-part-ii-examples-and-calculations","status":"publish","type":"post","link":"https:\/\/discover.restek.com\/ja\/blogs-de\/gnbl4834\/to-15-canister-relative-humidity-part-ii-examples-and-calculations","title":{"rendered":"TO-15 Canister Relative Humidity: Part II (Examples and Calculations)"},"content":{"rendered":"\n<p>In my last&nbsp;blog&nbsp;I left you hanging on how to calculate the theoretical relative humidity (% RH) in a canister. So to help us learn, I will use the two following example scenarios under which we may look at canister RH, and how the calculations are done: 1) we know how much water was put in a canister and what pressure and temperature the canister is at \u2013 so what is the relative humidity? 2) we know what relative humidity we desire and at what pressure and temperature &#8211; so how much water do we need to add to the canister?<\/p>\n\n\n\n<div style=\"height:20px\" aria-hidden=\"true\" class=\"wp-block-spacer\"><\/div>\n\n\n<div class=\"wp-block-image\">\n<figure class=\"aligncenter\"><img decoding=\"async\" src=\"https:\/\/discover.restek.com\/wp-content\/uploads\/blog-to-15-canister-relative-humidity-part-ii-examples-and-calculations-01.gif\" alt=\"relativehumidity\" class=\"wp-image-9263\" title=\"-\"><\/figure>\n<\/div>\n\n\n<div style=\"height:20px\" aria-hidden=\"true\" class=\"wp-block-spacer\"><\/div>\n\n\n\n<p>Recall from my first&nbsp;blog&nbsp;that relative humidity is defined as the ratio of the partial pressure of water vapor to the saturated vapor pressure of water at a set&nbsp;<em>temperature<\/em>. Temperature is italicized, as it is important to note that with increasing temperature (for a constant volume of air) saturation vapor pressure increases. The following figure is excellent for understanding the relationship between temperature and RH:<br role=\"presentation&quot;\" data-uw-rm-sr=\"\"><\/p>\n\n\n\n<p>This is the relationship between vapor denisty and temperature:<\/p>\n\n\n<div class=\"wp-block-image\">\n<figure class=\"aligncenter\"><img decoding=\"async\" src=\"https:\/\/discover.restek.com\/wp-content\/uploads\/blog-to-15-canister-relative-humidity-part-ii-examples-and-calculations-02.gif\" alt=\"humidity-graph\" class=\"wp-image-9264\" title=\"-\"><\/figure>\n<\/div>\n\n\n<p><br role=\"presentation\" data-uw-rm-sr=\"\"><\/p>\n\n\n\n<p>Now\u2026 time for us to visit physics 101 with our two examples:<\/p>\n\n\n\n<p><strong>Example 1:<\/strong>&nbsp;If 200 \u00b5L of H2O is injected into an evacuated 6 L canister @ 22.5 \u00b0C and then filled to a final pressure of 30 psig\u2026 what is the theoretical relative humidity?<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Recall: Saturation Vapor Density = 19.99 g\/m<sup>3<\/sup>\u00a0@ 22.5 \u00b0C<\/li>\n\n\n\n<li>Recall: Density of H<sub>2<\/sub>O = 0.99765874 g\/cm<sup>3<\/sup><\/li>\n<\/ul>\n\n\n\n<p>Calculation steps:<\/p>\n\n\n\n<ol start=\"1\" class=\"wp-block-list\">\n<li>Units conversion: 200 \u00b5L \u00f7 1000 \u00b5L\/cm\u00b3 = 0.200 cm\u00b3<\/li>\n\n\n\n<li>Mass of water in canister = density of water x volume: 0.99765874 g\/cm<sup>3\u00a0<\/sup>x 0.200 cm\u00b3 = 0.20 g<\/li>\n\n\n\n<li>Volume of gas in canister = size of canister x # of atmospheres: 6 L \u00f7 1000 L\/m<sup>3<\/sup>\u00a0x 3 atmospheres (30\u201d HG to 30 psig) = 0.018 m<sup>3<\/sup><\/li>\n\n\n\n<li>Vapor density in canister = mass of water \u00f7 volume of air (taken from 2 &amp; 3): 0.20 g \u00f7 0.018 m<sup>3<\/sup>\u00a0= 11.11 g\/m<sup>3<\/sup><\/li>\n\n\n\n<li>% Relative Humidity = vapor density \u00f7 saturation vapor density x 100: 11.11 g\/m<sup>3<\/sup>\u00a0\u00f7 19.99 g\/m<sup>3<\/sup>\u00a0x 100 = 55.77% RH<\/li>\n<\/ol>\n\n\n\n<p><strong>Example 2:<\/strong>&nbsp;If the desired theoretical relative humidity is 75% in an evacuated 6 L canister @ 22.5 \u00b0C filled to a final pressure of 30 psig\u2026 what volume of H2O needs to be injected into the canister?<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Recall: Saturation Vapor Density = 19.99 g\/m<sup>3<\/sup>\u00a0@ 22.5 \u00b0C<\/li>\n\n\n\n<li>Recall: Density of H<sub>2<\/sub>O = 0.99765874 g\/cm<sup>3<\/sup><\/li>\n<\/ul>\n\n\n\n<p>Calculation steps:<\/p>\n\n\n\n<ol start=\"1\" class=\"wp-block-list\">\n<li>Desired humidity (not relative, hence no %) is desired vapor density = ratio x saturation vapor density: 0.75 x 19.99 g\/m<sup>3<\/sup>\u00a0= 14.99 g\/m<sup>3<\/sup><\/li>\n\n\n\n<li>Volume of gas in canister = size of canister x # of atmospheres: 6 L \u00f7 1000 L\/m<sup>3<\/sup>\u00a0x 3 atmospheres (30\u201d HG to 30 psig) = 0.018 m<sup>3<\/sup><\/li>\n\n\n\n<li>Required mass of water in canister = desired vapor density x volume of gas in canister (taken from 1 &amp; 2): 14.99 g\/m<sup>3\u00a0<\/sup>x 0.018 m<sup>3<\/sup>\u00a0= 0.2699 g<\/li>\n\n\n\n<li>Required water injection volume = mass of water x density of water: 0.2699 g x 0.99765874 g\/cm<sup>3\u00a0<\/sup>= 0.2692 cm<sup>3<\/sup><\/li>\n\n\n\n<li>Units conversion: 0.2692 cm<sup>3\u00a0<\/sup>x 1000 \u00b5L\/cm\u00b3 = 269.2 \u00b5L<\/li>\n<\/ol>\n\n\n\n<p>So&#8230; considering that the majority of individuals who are interested in canister RH are probably going to be faced with scenario 2, I have gone ahead and put together this sophisticated RH calculator for those that are interested:<\/p>\n\n\n\n<p><a title=\"Canister RH Calculator - V1.01\" href=\"https:\/\/docs.google.com\/spreadsheet\/ccc?key=0AlmJdqxaWFzAdEtWWmZBTktGRUlqTFN5N2FGdU5Sb1E&amp;usp=sharing\" data-uw-rm-brl=\"false\" target=\"_blank\" rel=\"noopener\">Canister RH Calculator &#8211; V1.01<\/a><\/p>\n\n\n\n<p>Feel free to copy and paste into your own Excel workbook, just please keep in mind that this is strictly for 22.5 \u00b0C. In the meantime stay tuned for part III of this series, where we learn how canister RH can affect our results\u2026<\/p>\n\n\n\n<div style=\"height:100px\" aria-hidden=\"true\" class=\"wp-block-spacer\"><\/div>\n","protected":false},"excerpt":{"rendered":"<p>In my last blog I left you hanging on how to calculate the theoretical relative humidity (% RH) in a canister. So to help us learn, I will use the two following example scenarios under which we may look at&#8230;<\/p>\n","protected":false},"author":25,"featured_media":0,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"_kad_blocks_custom_css":"","_kad_blocks_head_custom_js":"","_kad_blocks_body_custom_js":"","_kad_blocks_footer_custom_js":"","_kadence_starter_templates_imported_post":false,"_kad_post_transparent":"","_kad_post_title":"","_kad_post_layout":"","_kad_post_sidebar_id":"","_kad_post_content_style":"","_kad_post_vertical_padding":"","_kad_post_feature":"","_kad_post_feature_position":"","_kad_post_header":false,"_kad_post_footer":false,"footnotes":""},"categories":[792],"tags":[],"industries-application":[2254,2253],"post-badge":[],"resource-type":[],"product-library":[],"resource-technique":[2331,2332,2336],"hf_cat_post":[623],"ppma_author":[445],"class_list":["post-51828","post","type-post","status-publish","format-standard","hentry","category-blogs-de","industries-application-analisi-dellaria","industries-application-ambientale","resource-technique-campionamento-dellaria","resource-technique-gascromatografia-gc","resource-technique-spettometria-di-massa-ms"],"acf":[],"taxonomy_info":{"category":[{"value":792,"label":"Blogs"}],"industries-application":[{"value":2254,"label":"Analisi dell\u2019Aria"},{"value":2253,"label":"Ambientale"}],"resource-technique":[{"value":2331,"label":"Campionamento dell\u2019Aria"},{"value":2332,"label":"Gascromatografia (GC)"},{"value":2336,"label":"Spettometria di Massa (MS)"}]},"featured_image_src_large":false,"author_info":{"display_name":"Jason S. Herrington, PhD","author_link":"https:\/\/discover.restek.com\/ja\/author\/jason-s-herrington-phd\/"},"comment_info":0,"category_info":[{"term_id":792,"name":"Blogs","slug":"blogs-de","term_group":0,"term_taxonomy_id":792,"taxonomy":"category","description":"","parent":0,"count":442,"filter":"raw","cat_ID":792,"category_count":442,"category_description":"","cat_name":"Blogs","category_nicename":"blogs-de","category_parent":0}],"tag_info":false,"authors":[{"term_id":445,"user_id":25,"is_guest":0,"slug":"jason-s-herrington-phd","display_name":"Jason S. Herrington, PhD","avatar_url":{"url":"https:\/\/discover.restek.com\/wp-content\/uploads\/people-herrington-jason.png","url2x":"https:\/\/discover.restek.com\/wp-content\/uploads\/people-herrington-jason.png"},"0":null,"1":"","2":"","3":"","4":"","5":"","6":"","7":"","8":""}],"_links":{"self":[{"href":"https:\/\/discover.restek.com\/ja\/wp-json\/wp\/v2\/posts\/51828","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/discover.restek.com\/ja\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/discover.restek.com\/ja\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/discover.restek.com\/ja\/wp-json\/wp\/v2\/users\/25"}],"replies":[{"embeddable":true,"href":"https:\/\/discover.restek.com\/ja\/wp-json\/wp\/v2\/comments?post=51828"}],"version-history":[{"count":3,"href":"https:\/\/discover.restek.com\/ja\/wp-json\/wp\/v2\/posts\/51828\/revisions"}],"predecessor-version":[{"id":74108,"href":"https:\/\/discover.restek.com\/ja\/wp-json\/wp\/v2\/posts\/51828\/revisions\/74108"}],"wp:attachment":[{"href":"https:\/\/discover.restek.com\/ja\/wp-json\/wp\/v2\/media?parent=51828"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/discover.restek.com\/ja\/wp-json\/wp\/v2\/categories?post=51828"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/discover.restek.com\/ja\/wp-json\/wp\/v2\/tags?post=51828"},{"taxonomy":"industries-application","embeddable":true,"href":"https:\/\/discover.restek.com\/ja\/wp-json\/wp\/v2\/industries-application?post=51828"},{"taxonomy":"post-badge","embeddable":true,"href":"https:\/\/discover.restek.com\/ja\/wp-json\/wp\/v2\/post-badge?post=51828"},{"taxonomy":"resource-type","embeddable":true,"href":"https:\/\/discover.restek.com\/ja\/wp-json\/wp\/v2\/resource-type?post=51828"},{"taxonomy":"product-library","embeddable":true,"href":"https:\/\/discover.restek.com\/ja\/wp-json\/wp\/v2\/product-library?post=51828"},{"taxonomy":"resource-technique","embeddable":true,"href":"https:\/\/discover.restek.com\/ja\/wp-json\/wp\/v2\/resource-technique?post=51828"},{"taxonomy":"hf_cat_post","embeddable":true,"href":"https:\/\/discover.restek.com\/ja\/wp-json\/wp\/v2\/hf_cat_post?post=51828"},{"taxonomy":"author","embeddable":true,"href":"https:\/\/discover.restek.com\/ja\/wp-json\/wp\/v2\/ppma_author?post=51828"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}