Determining whether the pre-filter (primary or secondary) needs to be replaced is quite simple. Just remember the 4 criteria and you can make the decision by observing and testing on-site without having to guess.
\n1. Check the pressure difference (the most accurate and standard method)
\nThis is the most common method used in HVAC and cleanroom systems:
\nWhen installing, record the initial pressure difference.
\nIf the pressure difference reaches twice the initial pressure difference, it’s time to replace it.
\nCommon experience values (for quick judgment only):
\nPrimary filter: Final resistance 90-150 Pa
\nSecondary filter: Final resistance 150-250 Pa
\nAs long as the pressure difference reaches this level, regardless of whether it’s dirty or not, it is recommended to replace it. Otherwise, the lifespan of the subsequent high-efficiency filter will be significantly shortened.
\n2. Check the appearance (the most intuitive)
\nWithout using instruments, you can also make the judgment:
\nThe filter material is obviously blackened, yellowed, or covered with dust
\nThe filter screen is deformed, collapsed, or bulging
\nThe frame, sealing area has chips, damage, or air leakage
\nThe surface has mold spots, water stains, or corrosion
\nIf any of these conditions occur, replace it immediately.
\n3. Feel the wind speed (simple and practical)
\nThe air volume at the outlet has significantly decreased
\nCompare the wind speed at the same outlet before and after, and it has decreased significantly
\nThe pressure difference and air change rate of the cleanroom do not meet the design requirements
\nThis basically indicates that the pre-filter is blocked.
\n4. Check the usage time (backup reference)
\nIf there is no pressure difference meter, make a conservative judgment based on time:
\nPrimary filter: 1-3 months<\/p>","protected":false},"excerpt":{"rendered":"
Determining whether the pre-filter (primary or secondary) needs to be replaced is quite simple. Just remember the 4 criteria and you can make the decision by observing and testing on-site without having to guess. 1. Check the pressure difference (the most accurate and standard method) This is the most common method used in HVAC and […]<\/p>","protected":false},"author":3,"featured_media":5290,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[92],"tags":[],"class_list":["post-5298","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-industry-technology"],"acf":[],"_links":{"self":[{"href":"https:\/\/www.bacintl.com\/es\/wp-json\/wp\/v2\/posts\/5298","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.bacintl.com\/es\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.bacintl.com\/es\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.bacintl.com\/es\/wp-json\/wp\/v2\/users\/3"}],"replies":[{"embeddable":true,"href":"https:\/\/www.bacintl.com\/es\/wp-json\/wp\/v2\/comments?post=5298"}],"version-history":[{"count":1,"href":"https:\/\/www.bacintl.com\/es\/wp-json\/wp\/v2\/posts\/5298\/revisions"}],"predecessor-version":[{"id":5299,"href":"https:\/\/www.bacintl.com\/es\/wp-json\/wp\/v2\/posts\/5298\/revisions\/5299"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.bacintl.com\/es\/wp-json\/wp\/v2\/media\/5290"}],"wp:attachment":[{"href":"https:\/\/www.bacintl.com\/es\/wp-json\/wp\/v2\/media?parent=5298"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.bacintl.com\/es\/wp-json\/wp\/v2\/categories?post=5298"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.bacintl.com\/es\/wp-json\/wp\/v2\/tags?post=5298"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}