A laminar flow hood creates a particle-free work environment by drawing air through a High-Efficiency Particulate Air (HEPA) filter. This filter removes airborne contaminants like dust and microorganisms. The filtered air moves across the workspace in a steady, unidirectional stream, either horizontally or vertically, preventing external air from compromising the work area. This consistent airflow protects sensitive materials, such as cell cultures or electronic components, from contamination during critical procedures. Regular cleaning is necessary to maintain the integrity of this sterile zone and ensure the hood functions as intended.
Necessary Safety Protocols and Supplies
Before cleaning, the hood should run for 15 to 30 minutes to purge existing airborne particles from the workspace. All items must be removed from the interior to expose the entire work surface. If the hood has a germicidal ultraviolet (UV) light, turn it off to prevent skin and eye exposure, and allow the unit to cool before handling components.
Personal Protective Equipment (PPE) is necessary to prevent contamination and protect the user from cleaning agents. This includes wearing a clean lab coat, eye protection, and sterile, non-shedding gloves. The appropriate cleaning agent is 70% isopropyl alcohol or 70% ethanol. This concentration effectively kills microorganisms without leaving harmful residues on the stainless steel surface. Use only lint-free wipes or cleanroom-grade cloths, as standard paper towels shed fibers that compromise the clean environment.
Step-by-Step Surface Cleaning Procedure
Cleaning the primary work area requires a systematic approach to prevent contamination redistribution. Apply the disinfectant solution directly to the lint-free wipe, never spraying the liquid onto the hood surfaces. Spraying can force contaminants into crevices, damage electrical components, or compromise the HEPA filter located behind the grille.
The wiping motion must be unidirectional and overlapping, moving from the cleanest area toward the dirtiest area. For most hoods, this means starting at the back wall, closest to the filter, and working toward the front opening. Use linear strokes to wipe the surface in sections, ensuring the entire area is covered.
Change the wipe frequently, folding it to expose a fresh surface or discarding it when soiled. This prevents the transfer of microorganisms and debris, which would negate the cleaning effort. After physical cleaning, apply a second application of the 70% alcohol solution. Allow it to remain wet for the recommended disinfectant dwell time to ensure maximum microbial inactivation before the solution evaporates.
Cleaning Specific Interior Components
Interior areas beyond the main work surface must be cleaned carefully. Side walls should be cleaned using the same unidirectional motion, typically wiping from top to bottom or back toward the front. Pay close attention to corners and seams where dust and debris accumulate.
The perforated grille or plenum cover, which protects the intake or exhaust path, must be cleaned with caution. Never spray cleaning agents directly onto this grille, as the liquid could damage the HEPA filter media positioned behind it. Instead, thoroughly dampen a lint-free wipe and gently swab the grille surface to remove accumulated particulate matter.
If the hood has a UV light bulb, wipe it down only when the unit is powered off and cool. Gently wipe the bulb with a dry or lightly dampened cloth to remove dust, as a dusty bulb reduces the UV light’s germicidal effectiveness. The HEPA filter itself is not meant to be cleaned by the user; wiping or spraying the filter will result in irreparable damage.
Establishing a Regular Cleaning Schedule
Consistency in cleaning is essential to maintaining a sterile environment. The work surface should be wiped down with disinfectant immediately before and after every use. This daily routine prevents the buildup of contaminants introduced during work procedures.
A comprehensive deep cleaning, including all interior surfaces, side walls, and the plenum cover, should be performed weekly or bi-weekly, depending on usage frequency. Laboratories working with sensitive materials may require daily deep cleaning to maintain sterility.
Beyond user efforts, a formal, regular maintenance schedule involving professional certification is necessary. The hood’s performance, including airflow velocity and HEPA filter integrity, must be tested and certified at least annually by a qualified technician. Maintaining a log of all cleaning activities, including the date, time, and the individual responsible, is a practice for quality control and compliance purposes.