Negative pressure weighing booths are core local isolation equipment in GMP pharmaceutical workshops. They prevent dust escape and cross-contamination during weighing, sampling, material splitting and sieving of high-potency drug powders, hormones, cytotoxic anti-tumor drugs and allergenic powders. Proper selection helps meet GMP regulations, operational safety, cleanroom validation and long-term operation & maintenance costs. Poor selection often leads to failed validation, powder leakage, frequent filter clogging and excessive personnel exposure. This article provides a practical selection framework covering user requirement specification (URS), core technical parameters, powder hazard classification, structural configuration, GMP compliance validation and common pitfalls.

Bacclean vertical flow clean benches achieve ISO Class 5 (Class 100) cleanliness with vertical unidirectional laminar airflow. All units comply with GMP and ISO 14644 standards. They are widely used in hospital clinical laboratories, pharmaceutical QC labs, aseptic compounding, microbial testing, cell culture, precision electronics assembly, cosmetic sterility inspection and other applications. Besides standard stock models, custom non‑standard solutions are available according to on‑site space and user requirement specification (URS). Each unit is delivered with PAO leak test and wind speed uniformity test reports, and supporting documents for IQ/OQ validation.

In hot air purification systems such as clean ovens, pharmaceutical dry heat depyrogenation, lithium battery sintering, coating curing ovens and semiconductor high-temperature processes, separated HEPA filters serve as the core terminal filtration components for high-temperature sections. Many on-site failures are not caused by filter media breakdown, but by the sealing adhesive aging, embrittlement and debonding under alternating cold and hot conditions or continuous high temperatures, resulting in bypass leakage and direct filter failure. Therefore, understanding the overall temperature resistance limits of separated HEPA filters, the material characteristics of different high-temperature adhesives, as well as the key points for selection and operation, is critical to ensuring stable operation of high-temperature purification systems and meeting PAO leak test and GMP validation requirements.

A horizontal flow clean bench is a local unidirectional laminar purification device. It delivers clean airflow horizontally to form an ISO Class 5 (Class 100) clean working zone. Unlike vertical flow clean benches where air flows downwards, the horizontal flow bench discharges clean air from the rear HEPA filter and blows forward in parallel. It features a short airflow path, uniform wind speed and low resistance, and is suitable for applications such as electronics assembly, optical component inspection, wafer testing and sample packaging where product protection is the priority. Nevertheless, the horizontal airflow blows directly toward the operator, and aerosols may drift toward the human body, so its application scope has clear limitations. To keep cleanliness stable and prevent particle overrun and product contamination, operators must strictly follow startup procedures, operation specifications, maintenance schedules and safety requirements.

In the clean purification industry, HEPA filters serve as the core terminal components for controlling particulate contaminants in the air. According to the internal support structure, they can be divided into separated HEPA filters and non-separated HEPA filters. Among them, the separated HEPA filter is a classic filter structure with early development and high technical maturity. Featuring high temperature resistance, large air volume, high dust holding capacity and strong stability, it remains the preferred filtration product for many demanding working conditions. It is widely used in clean systems for GMP pharmaceutical manufacturing, lithium battery, semiconductor, high-temperature ovens, coating, hospital clean operating departments and other fields.

As the most widely used local unidirectional flow purification equipment, the clean bench relies on fans and HEPA filters to form stable laminar flow and build a local clean environment inside the open operation chamber. Many buyers only distinguish between vertical flow and horizontal flow during selection, while lacking understanding of cleanliness standards and index differences. Improper selection may lead to unnecessary cost overrun, product contamination or failed validation. Combined with ISO14644 and EN1822 standards, this article introduces the classification, particle indicators, advantages and applicable scenarios of clean benches, to support selection for pharmaceutical, medical, electronics and laboratory projects.

Both automatic lift pass boxes and standard pass boxes are used for transferring small items between clean areas, or between clean and non-clean areas. They share the same core feature: a double-door interlock system that prevents both doors from opening simultaneously, so as to minimize air convection and cross-contamination. Their main differences lie in door opening mode, automation level, safety performance, optional purification functions and applicable scenarios.

The automatic roller shutter air shower pass chamber integrates cargo dedusting air shower and rapid isolation functions. It is a key equipment for clean workshops, logistics corridors and buffer rooms. Its operational stability directly affects the dedusting performance of the clean area, equipment service life and operation safety. Daily maintenance shall focus on four modules: roller shutter system, air shower dedusting system, electric control system and structural safety components, following the principle of “prevention first, regular maintenance and complete record keeping”.

Separated HEPA filters are core filtration components for cleanroom terminal air supply, laminar flow hoods, air shower tunnels, negative pressure weighing exhaust and other high-load applications. There is a substantial price gap across the market. Many low-cost alternatives only match the outer dimensions, while significant differences exist in filter media, workmanship, sealing, pressure drop and dust holding capacity. Such inferior products are prone to dust leakage, sharp pressure drop rise, short service life and failed PAO leak tests. When selecting premium filters, focus on the five core indicators below, and verify them against operating conditions and sealing configurations.

The HEPA filter of a horizontal laminar flow clean bench shall not be replaced merely according to service time. Its replacement should be comprehensively determined in combination with airflow velocity, pressure resistance, leak test results and cleanliness variation. Under normal operating conditions, the general replacement cycle of the HEPA filter ranges from 12 to 36 months. The cycle will be greatly shortened in dusty environments, with high operation frequency, continuous long-time running, or inadequate maintenance of the pre-filter.

Separated HEPA filters are core filtration components for cleanroom terminal air supply, laminar flow hoods, air shower tunnels, negative pressure weighing exhaust and other high-load working conditions. There is a large price gap among products on the market. Many low-cost products only match the external dimensions, while obvious gaps exist in filter media, manufacturing process, sealing, pressure drop and dust holding capacity. Problems such as dust leakage, rapid pressure drop rise, short service life and failed PAO leak test tend to occur in the later stage. When selecting premium products, focus on the five core indicators below, and verify them together with working conditions and matching sealing forms.

In GMP pharmaceutical workshops, QC laboratories, raw material dispensing, high-potency powder handling, and pathogenic microorganism testing, both negative pressure weighing booths and biological safety cabinets feature negative pressure protection. Many users confuse the two and mistakenly substitute one for the other, which may lead to cross-contamination of products, personnel exposure, and non-compliance during qualification audits. Although both rely on negative pressure airflow to contain aerosol dispersion, they differ completely in design orientation, protected targets, airflow patterns, protection levels and applicable working conditions. This article analyzes the equipment from core principles, protection objectives, classification, application scenarios, key distinctions and selection guidelines.