Laboratory Safety Services
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Testing, Inspection and Repair Services

Laboratory Safety Services Inc. offers testing, inspection, and repair services for all types of H.E.P.A. filtered equipment. Some of the equipment we work on:

Biological Safety Cabinets

Biological Safety Cabinets or BSC’s are divided into three classes based both on design and protection. Personnel protection is provided by face or inflow velocity. It carries air away from the operator of the device. Product protection is provided by Supply air. It floods the work zone of the BSC with HEPA filtered air protecting from particle contamination.

Class I BIOLOGICAL SAFETY CABINETS provide protection to personnel in the laboratory and H.E.P.A. filter air before exhausting it. The minimum face velocity of Class 1 BSC’s is 75 fpm.

Class II BSC’s are divided into four types based on design and exhaust characteristics. All types except the A1 must have contaminated positive pressure plenums surrounded by negative pressure zones. This insures that should the positive pressure plenum leak it will be contained within the unit and not escape into the laboratory. Types A2, B1 and B2 must be exhausted outside. Many Class II cabinets are built to meet National Sanitation Foundation Standard 49 (NSF 49) This standard provides specific construction and testing requirements.

Class II Type A1: These units have contaminated positive pressure plenums (not surrounded by negative plenums) Provides HEPA filtered supply air to protect the product in the unit. Has a minimum face velocity is 75 FPM to provide personnel protection. These units recirculate 70% of air and exhaust 30% back into the laboratory through a HEPA filter.

Class II Type A2 (formerly Class II type B3): this type of BSC has contaminated positive pressure plenums surrounded by negative plenums. Supply air is HEPA Filtered protecting the product from particle contamination. 70% of the air is recirculated within the unit, and the remaining 30% is HEPA filtered and exhausted to the outside environment through an exhaust duct. The minimum face velocity is 100 fpm. Connections to ducts should be by a thimble or canopy type transition.

Class II Type B1 Cabinets: This cabinet must have all contaminated positive pressure plenums surrounded by negative pressure zones. Supply air is HEPA filtered. HEPA filtered air is exhausted to the outside through a dedicated building exhaust system. In contrast to the A1 & A2 types 70% of the air is exhausted while only 30% is recirculated. These units can be used with small amounts of volatiles in the rear of the work zone. Minimum Face velocity is 100 FPM

Class II Type B2: These units are also known as “Total Exhaust Bio Safety Cabinets” because they do not recirculate any air within the unit. 100% of the air is exhausted. All contaminated plenums are under negative pressure. Supply air is HEPA filtered. Exhaust air is HEPA filtered and removed to the outside through a dedicated building exhaust system.

Class II Type B3: These units are now designated Class II Type A2. In the past some manufacturers posted A/B3 on the front of these units. This indicates that unit can stand alone in the lab as a type A or be connected to ductwork and exhausted to the outdoors to operate as a type B3 unit.

Class III Biological Safety Cabinet: These units are completely enclosed. Work in the unit is performed through gloves. The unit is under 0.5” Wg of negative pressure. Exhaust air is incinerated and HEPA filtered or double HEPA filtered prior to being exhausted.

Barrier Isolators: There are currently two types of these units.

Positive Pressure Barrier Isolators are for use in preparing non-hazardous pharmacy preparations. They provide a H.E.P.A. filtered environment to mix preparations usually through gloves or glove ports.

Negative Pressure Barrier Isolators are for use in the preparation of hazardous pharmaceutical preparations. They provide a H.E.P.A. filtered work area maintained under negative pressure to protect personnel and the surrounding environment from exposure to the agent.

Laminar Flow Clean Benches

These units provide a “clean” or greatly reduced particle loaded work zone. They may be horizontal or vertically oriented. Clean benches provide product protection only. No environmental or personnel protection is afforded.

Please note that in the past some parts of the industry attempted to differentiate Clean Benches from Biological Safety Cabinets by describing them as “horizontal laminar flow units” or “Vertical laminar flow units”. A clean bench in the horizontal or vertical orientation does not provide personnel protection in either orientation.

Clean Rooms

A “Clean Room “ is an early term for what are now better known as Controlled Environments. Generally these areas were designed to reduce the number of particulates in the room. Classifying particle levels in a designated area were described in a series of U.S. Federal Standards known as Federal Standard 209. The last version 209E, was not updated and has been replaced by an International Standard know as ISO 14644.

Equivalent particle classes are listed below:

Fed std 209Iso Class

In addition to Particle counting Pressure differentials between different particle cleanliness zones are important. Controlled environments often have several different levels of particle-reduced areas. It is important the areas with the lowest particle requirements be the highest in a stepped pressure scheme. That way particles are driven outward toward less stringently controlled areas.

Air volume and Room turnover rates are important aspects for keeping reduced particle zones in specification. As particles are generated room turnover rates keep particle levels in check.

Temperature, humidity and lighting may also be of consideration.

Containment Suites

These zones are also known as BL-3 Laboratories. These laboratories are built conduct research on hazardous airborne agents. They are designed with a decreasing pressure gradient intended to keep agents in the lab. The most hazardous areas are maintained at the lowest pressure. Air that is exhausted from these labs is often HEPA filtered. Supply air is also often HEPA filtered.

Fume Hoods (standard, bypass, auxiliary air, or H.E.P.A. filtered)

Fume Hood is a term used to describe a variety of units designed to protect personnel from vapors, fumes, aerosols and particulates. There are many different designs, which attempt to accomplish this goal.

Fume Hoods may be Constant Air Volume (CAV) or Variable Air Volume (VAV). CAV’s maintain a set volume of exhaust air independent of sash opening, while VAV’s change the volume of exhausted dependant on sash opening.

A Standard Fume Hood has a vertical sash that is positioned to provide worker protection and a set face velocity.

Bypass Fume Hoods have an additional opening that allows lab air to enter the unit through an alternate location to mitigate the face velocity at the work level.

Auxiliary Air Fume Hoods introduce outside air into the face area of the hood to reduce energy costs. They are less common now as it is difficult to introduce the air in such a way as to maintain adequate containment.

Walk in Hood. This term is a misnomer in that one should never walk into a large fume hood. The term often describes a hood with a very large face opening to accommodate drums or equipment.

Low Volume or Low velocity Fume Hoods are offered to save on energy costs by exhausting less HVAC treated laboratory air.

Another characteristic of a fume hood is the sash configuration. A fume hood sash may adjust vertically, horizontally or be compound in that it can be adjusted both ways. Other configurations are also seen.

Operating Room Walls

We inspect and service Hepa Filter Walls in Operating Rooms

Supply Systems and Walls

Details Coming Soon.

Oven and Vent H.E.P.A. Filters

Details Coming Soon.


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