Introduction
In pharmaceutical raw material handling, weighing active pharmaceutical ingredients (APIs), excipients, and hazardous fine chemicals creates significant airborne dust. Uncontrolled powder dispersal not only compromises product purity through cross-contamination but also exposes operators to active substances, violating Occupational Exposure Banding (OEB) guidelines.
To maintain sterile working environments and safeguard personnel, pharmaceutical processing plants rely on Powder Dispensing & Sampling Booths powered by Reverse Laminar Air Flow (RLAF) technology.
1. What Is Reverse Laminar Air Flow (RLAF) and How Does It Work?
Unlike standard vertical or horizontal Laminar Air Flow (LAF) units that blow purified air outward toward the operator, a Reverse Laminar Air Flow (RLAF) Booth operates under a recirculating negative pressure environment.
+---------------------------------------+
| RLAF AIR CIRCULATION FLOW |
+---------------------------------------+
| 1. HEPA Filtered Vertical Air Down |
| ↓ ↓ ↓ ↓ ↓ ↓ ↓ ↓ ↓ ↓ ↓ ↓ ↓ |
| 2. Powder Workstation / Weigh Scale |
| ↓ ↓ ↓ ↓ ↓ ↓ ↓ ↓ ↓ ↓ ↓ ↓ ↓ |
| 3. Low-Level Return Air Grilles |
| (Captures 90% Airborne Dust) |
| 4. Pre-Filter -> Intermediate Filter |
| -> HEPA Filter Recirculation |
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The 90/10 Air Balance Rule:
An RLAF booth continuously draws 90% of the air back through bottom-level return grilles for filtration, while bleeding off 10% of purified air to the surrounding room. This 10% air bleed creates a localized negative pressure zone inside the booth, preventing any chemical powder from escaping into the open warehouse or cleanroom corridor.
2. Comparing Dispensing & Sampling Booth Configurations
Depending on the stage of raw material handling, containment booths are configured for specific operational goals:
| Feature / Metric | Powder Dispensing Booth | Sampling Booth |
| Primary Function | Dispensing active powders into batch containers | Extracting small test samples from raw material drums |
| Material Handling | Large volume weighing & batching | Micro-sampling for QA/QC chemical analysis |
| Containment Level | OEB 3 to OEB 4 safety standards | OEB 2 to OEB 3 safety standards |
| Airflow Pattern | Vertical Reverse Laminar Airflow | Vertical Reverse Laminar Airflow |
| Filtration Setup | 3-Stage: Pre-filter (G4), EU9, HEPA (H14) | 3-Stage: Pre-filter (G4), EU9, HEPA (H14) |
3. Essential Features for USFDA & GMP Compliance
- Three-Stage Filtration: Primary G4 pre-filters, F9 secondary filters, and terminal H14 HEPA filters (99.995% efficiency at 0.3 microns).
- Differential Pressure Monitoring: Dedicated Magnehelic gauges mounted across each filter stage to track clogging and pressure drops in real time.
- Air Velocity Control: Auto-balancing centrifugal blowers that maintain a uniform downflow velocity of 0.45 m/s ± 20% (90 fpm ± 20%).
- SS 304 / SS 316L Heavy Duty Construction: Seamless, cGMP-compliant stainless steel housing with coved internal corners for quick wiping and cleaning.
Safeguard Your Personnel with Audit-Ready Dispensing Booths
Protect your operators from active chemical dust and maintain total containment during raw material sampling with custom-engineered equipment from SR Air System (Pass Box MFG). We design and manufacture SS 304 / SS 316L Reverse Laminar Air Flow (RLAF) Dispensing & Sampling Booths fitted with 3-stage filtration, flameproof motor options, and automated PLC controls built to conform to USFDA, EU-GMP, and ISO standards.
Need a custom powder containment booth for your raw material warehouse?
Speak directly with our containment engineers at +91-7984145193 or email your specifications to info@passboxmfg.com.
