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Fault 1: PAO leakage alarm at the frame, no leakage detected on filter paper<\/p>\n
No leak points are found on the filter medium, and leakage is concentrated at the sealing position around the filter frame, which belongs to bypass leakage. It can be divided into two types: glue leakage at the frame of the filter itself; leakage at the sealing interface of the complete assembly.<\/p>\n
Step 1: Troubleshoot the assembly sealing interface. For knife-edge structure: Check the locking state of compression blocks or buckles. Insufficient compression results in unsealed joints; over-compression at a single point causes frame warping and local gaps. Lift out the filter and check whether the sealing ring is damaged or displaced, and whether sheet metal debris or dust is trapped inside the sealing ring groove. Aging of the sealing ring and insufficient compression can also lead to leak points. Handling: Clean the sealing groove, replace the aged sealing ring, place the filter smoothly, compress evenly on all sides, and re-perform leakage test.<\/p>\n
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For gel seal structure: Check whether the knife edge has burrs or deformation, whether impurities are trapped between the knife edge and gel, and whether the filter is fully seated under its own weight. Replace the filter directly if burrs scratch the gel.<\/p>\n
Step 2: Troubleshoot glue injection on the filter frame. If leakage still exists after eliminating assembly issues, lift out the filter and check the glue injection area where filter medium connects to the frame for broken glue or bubble gaps. Glue injection defects are inherent manufacturing faults and cannot be repaired on site; replace the filter directly.<\/p>\n
Fault 2: PAO leakage detected on filter medium<\/p>\n
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Leakage alarm occurs on filter medium. Inducing factors include inherent defects of filter medium from factory; filter medium punctured by hard objects during transportation and installation; adhesive line peeling and filter pleat cracking caused by wind pressure impact. Lift out the filter and visually inspect the filter medium surface for holes or scratches; check whether large areas of hot melt adhesive lines peel off and whether filter pleats tear. Damaged filter medium cannot be repaired and the filter shall be scrapped and replaced immediately. Meanwhile, review transportation and installation procedures to avoid bump damage to subsequent equipment. Note: Distinguish real alarm from instantaneous false alarm caused by too fast probe movement. Slow down the probe speed and repeat scanning at the alarm position for confirmation.<\/p>\n
Fault 3: Rapid pressure drop rise within a short time, insufficient air volume and air change rate in cleanroom<\/p>\n
Prioritize checking the upstream pre-filtration system. If primary and medium efficiency filters are not replaced upon expiry and lose interception capacity, a large amount of dust directly impacts HEPA filter medium and causes rapid clogging of HEPA filters. This is the most common cause in new energy workshops. Replace upstream pre-filters in a timely manner. Verify the actual operating conditions of air conditioner and FFUs, confirm the fan speed has not been reduced. Fan frequency reduction will synchronously lower pressure drop readings, creating a false impression of low filter resistance while actual supply air volume is insufficient. Such pressure drop data cannot be used for judgment. Check whether the air inlet side of the filter is partially covered by thermal insulation debris or sheet metal dust, which reduces effective filtration area and leads to abnormal high pressure drop. Clean upstream debris to resolve the issue. Improper model selection can also trigger this fault: Using thin 50mm separatorless HEPA filters with low dust holding capacity in high-dust conditions leads to insufficient filter medium area, poor dust holding capacity and drastically shortened service life. Evaluation shall be conducted for replacement with thicker filter products in later stage.<\/p>\n
Fault 4: Large resistance dispersion among filters of the same batch, uneven air volume after parallel connection<\/p>\n
In large-scale FFU projects with hundreds of filters in parallel, some filters have high resistance and corresponding FFUs deliver low air volume, resulting in insufficient local air change rate; filters with low resistance operate under overloaded air flow and disturb airflow pattern. Root cause: Only sampling inspection is conducted instead of individual testing for every filter before delivery, leading to large performance dispersion of batch products. Handling: Check individual factory test reports and replace filters with excessive resistance deviation. Clarify requirements of individual testing and acceptance indicators for resistance dispersion at the tender stage of new projects to avoid risks from the supply side.<\/p>\n
Fault 5: Hot melt adhesive line peeling and collapse of filter pleats<\/p>\n
Symptoms: Intermittent leakage during on-site filter leakage test; gradual abnormal rise of pressure drop. After disassembly, filter pleats lean against each other and adhesive lines break and peel off. Three inducing factors:<\/p>\n
Poor hot melt adhesive process during manufacturing with sparse adhesive lines and insufficient bonding strength;<\/p>\n<\/li>\n
Poor-quality hot melt adhesive loses bonding performance under long-term high humidity in cleanrooms;<\/p>\n<\/li>\n
Severe pulse impact of system wind pressure repeatedly pulls the adhesive lines. Peeling of adhesive lines is irreversible damage and the filter shall be replaced directly. For projects under high humidity conditions, specify products with moisture-resistant hot melt adhesive technology during model selection. For working conditions with violent wind pressure fluctuation, evaluate switching to higher mechanical strength separators HEPA filters.<\/p>\n<\/li>\n<\/ol>\n
Fault 6: Leakage test passes at initial operation stage, but intermittent leakage occurs after a period of operation<\/p>\n
Intermittent leak points appear and disappear with changes of system wind pressure. For knife-edge sealing applications, the problem is mostly caused by permanent compression deformation of aging sealing rings or slight frame warping due to temperature variation. For gel seal type, microcracks form on aging gel. For separatorless filters, partial detachment of adhesive lines makes pleats open and close with wind pressure variation, resulting in variable leak points. Troubleshooting: Check operation logs, review cleanroom temperature, humidity and VHP disinfection frequency. Remove filters during overhaul window, visually inspect the condition of sealing rings, adhesive lines and gel. Replace aged components and filters directly, and do not continue operation with hidden risks.<\/p>\n
General Principles for Fault Troubleshooting<\/p>\n
Check external factors before filter body; check system conditions, frame accessories and installation assembly before confirming filter manufacturing defects. Do not directly conclude product quality faults once leakage alarm occurs. A large number of on-site faults originate from supporting accessories and operation procedures.<\/p>\n
Bacclean provides technical support for fault troubleshooting after project delivery. The complete system of separatorless HEPA filters includes filter body, sealing rings, air outlet \/ FFU frame, storage & transportation, installation, maintenance and disinfection. Weakness in any link will trigger faults. Full-process control is required to guarantee long-term stable operation of equipment.<\/p>","protected":false},"excerpt":{"rendered":"
Separatorless HEPA filters frequently suffer from three major faults during commissioning and long-term operation: PAO leakage detection failure, fluctuating pressure drop, and hot melt adhesive line failure. Fault root causes fall into three categories: manufacturing defects of the filter itself; issues with supporting FFUs, air supply frame, sealing rings; improper storage, transportation, installation and maintenance operations. Similar fault symptoms may stem from entirely different root causes. If the filter quality is directly judged as defective and repeated disassembly is carried out blindly, it will further damage the equipment and delay project commissioning progress. This article sorts out frequent on-site faults, analyzes inducing factors, and provides step-by-step troubleshooting and handling solutions to help engineering, validation and maintenance personnel quickly locate problems.<\/p>","protected":false},"author":3,"featured_media":6130,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[91],"tags":[],"class_list":["post-6129","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-industry-news"],"acf":[],"_links":{"self":[{"href":"https:\/\/www.bacintl.com\/ar\/wp-json\/wp\/v2\/posts\/6129","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.bacintl.com\/ar\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.bacintl.com\/ar\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.bacintl.com\/ar\/wp-json\/wp\/v2\/users\/3"}],"replies":[{"embeddable":true,"href":"https:\/\/www.bacintl.com\/ar\/wp-json\/wp\/v2\/comments?post=6129"}],"version-history":[{"count":2,"href":"https:\/\/www.bacintl.com\/ar\/wp-json\/wp\/v2\/posts\/6129\/revisions"}],"predecessor-version":[{"id":6134,"href":"https:\/\/www.bacintl.com\/ar\/wp-json\/wp\/v2\/posts\/6129\/revisions\/6134"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.bacintl.com\/ar\/wp-json\/wp\/v2\/media\/6130"}],"wp:attachment":[{"href":"https:\/\/www.bacintl.com\/ar\/wp-json\/wp\/v2\/media?parent=6129"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.bacintl.com\/ar\/wp-json\/wp\/v2\/categories?post=6129"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.bacintl.com\/ar\/wp-json\/wp\/v2\/tags?post=6129"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}