{"id":19820,"date":"2026-11-06T18:36:04","date_gmt":"2026-11-06T15:36:04","guid":{"rendered":"https:\/\/azeidkgroup.com\/sa\/media-center\/"},"modified":"2026-11-10T16:31:19","modified_gmt":"2026-11-10T13:31:19","slug":"concealed-sprinkler-head","status":"publish","type":"post","link":"https:\/\/azeidkgroup.com\/en\/sa\/media-center\/concealed-sprinkler-head\/","title":{"rendered":"Concealed Sprinkler (Concealed Sprinkler Head): Cover Plate, Temperature Ratings and Suspended Ceiling Installation"},"content":{"rendered":"\t\t<div data-elementor-type=\"wp-post\" data-elementor-id=\"19820\" class=\"elementor elementor-19820 elementor-19819 elementor-bc-flex-widget\" data-elementor-post-type=\"post\">\n\t\t\t\t<div class=\"elementor-element elementor-element-b5d83b5 e-con-full az-el-article e-flex e-con e-parent\" data-id=\"b5d83b5\" data-element_type=\"container\" data-e-type=\"container\">\n\t\t\t\t<div class=\"elementor-element elementor-element-09a48af elementor-widget elementor-widget-text-editor\" data-id=\"09a48af\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t<div class=\"elementor-widget-container\">\n\t\t\t\t\t\t\t\t\t<p class=\"az-intro\">A <strong>concealed sprinkler<\/strong> (concealed sprinkler head) is a pendent fire sprinkler whose body sits above the <strong>suspended ceiling<\/strong>, hidden by a flat cover plate that drops at a lower temperature than the sprinkler&#8217;s own operating temperature; the deflector then drops and the sprinkler operates. It is chosen for architectural ceilings in hotels, offices and hospitals, provided it is closely coordinated with the ceiling and used only with the cover plate listed for it.<\/p>\n<p>This guide focuses on the concealed sprinkler specifically: how it works, the role of the cover plate and its two temperatures, how it is coordinated with the suspended ceiling during construction, its pros and cons against an exposed pendent sprinkler, and what is checked during maintenance. For K-factor, bulb colours and response type across all sprinkler types, see <a href=\"\/en\/sa\/media-center\/sprinkler-head-types-k-factor-temperature\/\">Sprinkler Head Types: K-Factor, Temperature Rating and Response<\/a>.<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-05861e4 elementor-widget elementor-widget-text-editor\" data-id=\"05861e4\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t<div class=\"elementor-widget-container\">\n\t\t\t\t\t\t\t\t\t<div class=\"az-keybox\"><h2>Key points<\/h2><ul><li>A concealed sprinkler has two temperatures: the cover plate&#8217;s and the sprinkler&#8217;s, and both are ordered together as shown in the datasheet.<\/li><li>The cover plate is part of the listed sprinkler, so it must not be swapped for another model&#8217;s plate or painted on site.<\/li><li>Correct installation depends on the distance from the sprinkler fitting to the ceiling surface, so coordination with the ceiling contractor is a requirement, not a detail.<\/li><li>It gives a clean look and better protection against tampering, at a usually higher cost and with more sensitivity to installation and maintenance errors.<\/li><li>NFPA 25 (2026 edition) requires missing or deficient cover plates to be replaced with listed plates from the same sprinkler assembly.<\/li><\/ul><\/div>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-f1bfc24 elementor-widget elementor-widget-text-editor\" data-id=\"f1bfc24\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t<div class=\"elementor-widget-container\">\n\t\t\t\t\t\t\t\t\t<h2>What is a concealed sprinkler and how does it work?<\/h2>\n<p>A concealed sprinkler is essentially a pendent sprinkler whose body is hidden in a cup fixed in the ceiling opening and covered by a flat round plate, so only a smooth surface close to the ceiling colour is visible. The datasheet for TYCO Series RFII (Royal Flush II) sprinklers describes the operating sequence in this order:<\/p>\n<ol><li>Heat softens the solder points holding the cover plate to the retaining ring.<\/li><li>The plate separates and falls away from the sprinkler.<\/li><li>The deflector drops into its operating position on guide pins.<\/li><li>Heat continues to act on the glass bulb until it breaks at its rating.<\/li><li>The seal assembly releases, water flows and the deflector distributes it over the coverage area.<\/li><\/ol>\n<p>In other words, the sprinkler does not operate just because the plate falls; the plate dropping is the first step that exposes the sprinkler, which then operates at its own rating. That is why the two temperatures differ.<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-4373c20 elementor-widget elementor-widget-text-editor\" data-id=\"4373c20\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t<div class=\"elementor-widget-container\">\n\t\t\t\t\t\t\t\t\t<h2>What are the temperature ratings of a concealed sprinkler and its cover plate?<\/h2>\n<p>Each cover plate is listed with a specific sprinkler rating. For TYCO RFII models TY3531 and TY3551, as published on AZEIDK&#8217;s product page:<\/p>\n<div class=\"az-table-wrap\"><table><thead><tr><th>Sprinkler rating<\/th><th>Cover plate rating<\/th><th>Note<\/th><\/tr><\/thead><tbody><tr><td>68\u00b0C (155\u00b0F)<\/td><td>59\u00b0C (139\u00b0F)<\/td><td>Ordinary rating for most offices, hotels and corridors<\/td><\/tr><tr><td>93\u00b0C (200\u00b0F)<\/td><td>74\u00b0C (165\u00b0F)<\/td><td>For spaces with higher ambient temperature, per the design<\/td><\/tr><\/tbody><\/table><\/div>\n<p>The rule: do not fit a plate whose rating does not match the sprinkler, and do not mix plates from different models even if the diameter matches. The operating temperature is set from the maximum ambient temperature of the space under the adopted reference, as explained in the <a href=\"\/en\/sa\/media-center\/nfpa-13-sprinkler-systems-standard-guide\/\">NFPA 13 standard guide<\/a>.<\/p>\n<p>The TY3531 page includes an important note: the model is Quick Response under UL and C-UL listings, but FM does not approve concealed sprinklers as &#8220;quick response&#8221;. If the project specification requires QR with an FM reference, check with the consultant before selecting a concealed sprinkler.<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-a4a7ce4 elementor-widget elementor-widget-text-editor\" data-id=\"a4a7ce4\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t<div class=\"elementor-widget-container\">\n\t\t\t\t\t\t\t\t\t<h2>What does the cover plate do?<\/h2>\n<p>The cover plate is not a decorative cap that can be changed freely; it is part of the listed sprinkler, and its solder rating, shape and gap from the ceiling affect how quickly heat reaches the sprinkler. Requirements published on AZEIDK&#8217;s RFII page include:<\/p>\n<ul><li>Use only original cover plates from the same series with factory finish.<\/li><li>Do not paint the sprinkler or cover plate on site.<\/li><li>Maintain the nominal air gap between plate and ceiling (3\/32 in on this model).<\/li><li>Do not install the plate in a way that lifts the ceiling tile out of position.<\/li><li>Do not use the sprinkler where air pressure above the ceiling is higher than below it.<\/li><li>Replace the plate immediately if it is detached in service.<\/li><\/ul>\n<p>Plates are available in several factory colours and finishes, so order the colour with the supply rather than painting it later to match the ceiling.<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-15f5e9d elementor-widget elementor-widget-text-editor\" data-id=\"15f5e9d\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t<div class=\"elementor-widget-container\">\n\t\t\t\t\t\t\t\t\t<h2>How is a concealed sprinkler coordinated with the suspended ceiling?<\/h2>\n<p>This is where most concealed sprinkler problems arise on site. The sprinkler is fitted to the branch line before the ceiling is closed, the cup sets the body position, and the plate is fitted after finishing. Each model has published installation limits. For TYCO RFII, for example:<\/p>\n<ul><li>Distance from the sprinkler fitting face to the ceiling surface: 1.75 to 2.25 in (about 44 to 57 mm).<\/li><li>Ceiling hole diameter: 2.375 to 2.625 in (about 60 to 67 mm).<\/li><li>Cover plate diameter: 3.25 in (about 83 mm).<\/li><li>Vertical adjustment up to 1\/2 in (12.7 mm) through the plate&#8217;s engagement with the cup.<\/li><\/ul>\n<p>In practice, the suspended ceiling level must be fixed in the shop drawings before the drop <strong>pipes<\/strong> to the sprinklers are cut. If the ceiling level changes after installation by more than the adjustment range, the fix is to modify the drop, not to over-tighten or loosen the sprinkler; the product page prohibits compensating for incorrect height by changing the tightening.<\/p>\n<p>A benefit of this two-part design, as the product page notes, is that the sprinkler can be installed and the network pressure-tested before the ceiling is fitted, and the ceiling finished without the final plate, with a temporary protective cap preventing damage during plaster and paint work. The cap must be removed after the ceiling is complete and before the plate is fitted. The <a href=\"\/en\/sa\/services\/shop-drawings-coordination\/\">shop drawings and coordination<\/a> service helps settle these levels early.<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-b66671d elementor-widget elementor-widget-text-editor\" data-id=\"b66671d\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t<div class=\"elementor-widget-container\">\n\t\t\t\t\t\t\t\t\t<h2>What are the pros and cons of a concealed sprinkler versus a pendent sprinkler?<\/h2>\n<div class=\"az-table-wrap\"><table><thead><tr><th>Criterion<\/th><th>Concealed sprinkler<\/th><th>Exposed pendent sprinkler<\/th><\/tr><\/thead><tbody><tr><td>Appearance<\/td><td>Flat surface close to the ceiling colour<\/td><td>Body and deflector visible below the ceiling<\/td><\/tr><tr><td>Exposure to tampering and impact<\/td><td>Lower, because the body is inside the ceiling<\/td><td>Higher, especially with low ceilings<\/td><\/tr><tr><td>Temperature ratings<\/td><td>Two: plate and sprinkler<\/td><td>Sprinkler only<\/td><\/tr><tr><td>Installation sensitivity<\/td><td>High: ceiling level, hole and plate gap<\/td><td>Lower, with the listed escutcheon still important<\/td><\/tr><tr><td>Cost<\/td><td>Usually higher for sprinkler and plate<\/td><td>Usually lower<\/td><\/tr><tr><td>Listing limitations<\/td><td>Such as FM QR limits and air pressure above the ceiling<\/td><td>Usually fewer<\/td><\/tr><tr><td>Maintenance<\/td><td>Inspect plates and replace defective ones with matching plates<\/td><td>Inspect sprinkler, escutcheon, paint and corrosion<\/td><\/tr><\/tbody><\/table><\/div>\n<p>Neither is better in absolute terms. The concealed type suits spaces where the interior design calls for a clean ceiling or where tampering is a concern, while the exposed pendent remains the practical choice in service areas and simple suspended ceilings. The recessed sprinkler is a middle option in which the deflector stays visible.<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-09a6b8f elementor-widget elementor-widget-text-editor\" data-id=\"09a6b8f\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t<div class=\"elementor-widget-container\">\n\t\t\t\t\t\t\t\t\t<h2>Where are concealed sprinklers used?<\/h2>\n<p>AZEIDK&#8217;s product pages list applications such as hotels, restaurants, offices, hospitals, shopping centres, educational facilities and airport corridors. The TYCO range AZEIDK offers includes three concealed models for different purposes:<\/p>\n<ul><li><a href=\"\/en\/sa\/products\/tyco-series-rfii-royal-flush-ii-concealed-pendent-sprinklers-ty3531-and-ty3551\/\">Royal Flush II models TY3531 and TY3551<\/a>: standard coverage, K5.6, quick or standard response.<\/li><li><a href=\"\/en\/sa\/products\/tyco-rfii-c-concealed-corridor-sprinkler-ty3582\/\">RFII-C concealed corridor sprinkler TY3582<\/a>: for long narrow light hazard corridors, with coverage up to 28 \u00d7 10 ft (about 8.5 \u00d7 3.1 m) under its listing conditions.<\/li><li><a href=\"\/en\/sa\/products\/tyco-rfii-mri-non-magnetic-concealed-pendent-sprinkler-ty3537\/\">RFII-MRI sprinkler TY3537<\/a>: non-magnetic for MRI rooms, with extended coverage up to 20 \u00d7 20 ft, installed in the room ceiling, not inside the scanner.<\/li><\/ul>\n<p>Model, rating and finish follow the hydraulic calculations, occupancy and consultant specification. For other TYCO sprinklers, see <a href=\"\/en\/sa\/media-center\/tyco-sprinkler-selection\/\">selecting TYCO sprinklers for projects<\/a>.<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-7b67790 elementor-widget elementor-widget-text-editor\" data-id=\"7b67790\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t<div class=\"elementor-widget-container\">\n\t\t\t\t\t\t\t\t\t<h2>What is inspected on a concealed sprinkler during maintenance?<\/h2>\n<p>During periodic inspection you see the plate, not the sprinkler. So the technician focuses on what the plate surface shows:<\/p>\n<ul><li>Missing or misaligned plates, or plates stuck to the ceiling by paint.<\/li><li>Plates painted on site, dirty or corroded.<\/li><li>Plates lifted off the ceiling or recessed more than permitted.<\/li><li>Any new ceiling work that changed levels or added insulation above the sprinklers.<\/li><\/ul>\n<p>NFPA 25 (2026 edition, section 5.2.1.1.5) requires concealed sprinkler cover plates that are missing, or that show deficiencies such as damage, corrosion or paint applied by someone other than the manufacturer that harms performance, to be replaced with listed plates that are part of the listed sprinkler assembly, and plates found stuck to the ceiling to be replaced as well. The <a href=\"\/en\/sa\/media-center\/nfpa-25-itm-water-based-systems-guide\/\">NFPA 25 guide to inspecting, testing and maintaining water-based systems<\/a> covers the remaining items.<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-165d6dd elementor-widget elementor-widget-text-editor\" data-id=\"165d6dd\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t<div class=\"elementor-widget-container\">\n\t\t\t\t\t\t\t\t\t<h2>FAQ<\/h2>\n<div class=\"az-faq\"><details class=\"az-faq__item\"><summary><h3>Does a concealed sprinkler operate when the cover plate drops?<\/h3><\/summary><p>No. The plate dropping only exposes the sprinkler; the sprinkler operates when its bulb breaks at its rating, which is higher than the plate&#8217;s.<\/p><\/details><details class=\"az-faq__item\"><summary><h3>Can I paint a concealed sprinkler cover plate to match the ceiling?<\/h3><\/summary><p>Not on site. The RFII page prohibits painting the sprinkler or plate; factory colours and finishes can be ordered with the supply.<\/p><\/details><details class=\"az-faq__item\"><summary><h3>Can I fit another company&#8217;s plate if the diameter matches?<\/h3><\/summary><p>No. The plate is part of the listed sprinkler, and NFPA 25 requires a replacement plate to be listed as part of the same sprinkler assembly.<\/p><\/details><details class=\"az-faq__item\"><summary><h3>What is the difference between concealed and recessed sprinklers?<\/h3><\/summary><p>In a recessed sprinkler part of the body sits in the ceiling and the deflector stays visible; a concealed sprinkler is covered by a flat plate that drops before it operates.<\/p><\/details><details class=\"az-faq__item\"><summary><h3>Are concealed sprinklers suitable for warehouses?<\/h3><\/summary><p>They are usually not used there; warehouses need storage sprinklers chosen for storage type and height, and the corridor and MRI models shown here are intended for light hazard per their pages.<\/p><\/details><\/div>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-73ee4f0 elementor-widget elementor-widget-text-editor\" data-id=\"73ee4f0\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t<div class=\"elementor-widget-container\">\n\t\t\t\t\t\t\t\t\t<h2>Summary<\/h2>\n<p>A concealed sprinkler suits architectural ceilings provided three things are respected: the cover plate matches the sprinkler and its rating, the suspended ceiling level is fixed before installation, and plates are inspected and defective ones replaced with matching listed plates during maintenance.<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-3b59836 elementor-widget elementor-widget-text-editor\" data-id=\"3b59836\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t<div class=\"elementor-widget-container\">\n\t\t\t\t\t\t\t\t\t<p class=\"az-cta\"><strong>Need concealed sprinklers for a hotel, office or healthcare project?<\/strong> AZEIDK supplies the TYCO concealed sprinklers shown in its <a href=\"\/en\/sa\/products\/\">product catalogue<\/a>, and our <a href=\"\/en\/sa\/solutions\/fire-fighting-systems\/\">fire fighting systems<\/a> team can review the model, operating temperature and ceiling coordination before supply. <a href=\"\/en\/sa\/contact\/\">Request a quotation<\/a><\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-d130bf4 elementor-widget elementor-widget-text-editor\" data-id=\"d130bf4\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t<div class=\"elementor-widget-container\">\n\t\t\t\t\t\t\t\t\t<div class=\"az-source\"><strong>References:<\/strong> <a href=\"\/en\/sa\/products\/tyco-series-rfii-royal-flush-ii-concealed-pendent-sprinklers-ty3531-and-ty3551\/\" rel=\"noopener\" target=\"_blank\">TYCO RFII TY3531\/TY3551<\/a> (AZEIDK), <a href=\"\/en\/sa\/products\/tyco-rfii-c-concealed-corridor-sprinkler-ty3582\/\" rel=\"noopener\" target=\"_blank\">TYCO RFII-C TY3582<\/a> (AZEIDK), <a href=\"\/en\/sa\/products\/tyco-rfii-mri-non-magnetic-concealed-pendent-sprinkler-ty3537\/\" rel=\"noopener\" target=\"_blank\">TYCO RFII-MRI TY3537<\/a> (AZEIDK), <a href=\"https:\/\/www.nfpa.org\/codes-and-standards\/nfpa-25-standard-development\/25\" rel=\"noopener\" target=\"_blank\">NFPA 25<\/a> (NFPA), and <a href=\"https:\/\/blog.qrfs.com\/p23-when-do-i-need-to-replace-a-fire-sprinkler-escutcheon-or-cover-plate-new-rules\/\" rel=\"noopener\" target=\"_blank\">explanation of NFPA 25 cover plate replacement changes<\/a> (QRFS)<\/div>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t","protected":false},"excerpt":{"rendered":"<p>Concealed sprinkler guide: how it works, sprinkler and cover plate ratings, suspended ceiling coordination, pros and cons vs pendent, and NFPA 25 checks.<\/p>\n","protected":false},"author":0,"featured_media":22285,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[221],"tags":[],"azeidk_region":[223],"class_list":["post-19820","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-azeidk-articles"],"acf":[],"_links":{"self":[{"href":"https:\/\/azeidkgroup.com\/en\/wp-json\/wp\/v2\/posts\/19820","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/azeidkgroup.com\/en\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/azeidkgroup.com\/en\/wp-json\/wp\/v2\/types\/post"}],"replies":[{"embeddable":true,"href":"https:\/\/azeidkgroup.com\/en\/wp-json\/wp\/v2\/comments?post=19820"}],"version-history":[{"count":1,"href":"https:\/\/azeidkgroup.com\/en\/wp-json\/wp\/v2\/posts\/19820\/revisions"}],"predecessor-version":[{"id":19833,"href":"https:\/\/azeidkgroup.com\/en\/wp-json\/wp\/v2\/posts\/19820\/revisions\/19833"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/azeidkgroup.com\/en\/wp-json\/wp\/v2\/media\/22285"}],"wp:attachment":[{"href":"https:\/\/azeidkgroup.com\/en\/wp-json\/wp\/v2\/media?parent=19820"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/azeidkgroup.com\/en\/wp-json\/wp\/v2\/categories?post=19820"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/azeidkgroup.com\/en\/wp-json\/wp\/v2\/tags?post=19820"},{"taxonomy":"azeidk_region","embeddable":true,"href":"https:\/\/azeidkgroup.com\/en\/wp-json\/wp\/v2\/azeidk_region?post=19820"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}