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Improving Chemists’ Safety in Research and Development Laboratories:��By Eliminating all Bench-Level Obstructions with a MAC Hood Support Safety Device

Tim McKibben

Synthcon, LLC

SERMACS 2023

SERMACS 2023 copyright @Synthcon LLC T. McKibben

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Why Develop the Safety Device?

Immediate need to ensure maximum safety in the lab due to:

Contract manufacturing of highly toxic materials.
Self employed, owned the company – increased liability with no other entity responsible for safety.
Developed and utilized the device for more than 6 years while patent process continues.

SERMACS 2023 copyright @Synthcon LLC T. McKibben

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Individual Fume Generators Used to Videotape Chemical Fume Patterns

SERMACS 2023 copyright @Synthcon LLC T. McKibben

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Best Method�to Study Chemical Fume Flow Patterns is Slow-Motion Video

SERMACS 2023 copyright @Synthcon LLC T. McKibben

Dry Ice in Warm Water

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What happens to the fumes

when the sash is closed?

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Goal is to Prevent Fumes From Escaping the Hood

SERMACS 2023 copyright @Synthcon LLC T. McKibben

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Chemical Vapor Density is Very Important

313 chemical vapor densities compared (94% of those chemicals have a density heavier than air).
4.1% vapor densities are lighter than air
0.9% = vapor densities are equal to air
94.8% vapor densities are heavier than air

SERMACS 2023 copyright @Synthcon LLC T. McKibben

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Dense Fume Behavior With Sash Open then Closed - 2017

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Fume Hood Prior to MHS Installation – Left Side

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Fume Hood Prior to MHS Installation –�Right Side�

SERMACS 2023 copyright @Synthcon LLC T. McKibben

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Intended Exit Pathway (Blocked), Internal Airflow Patterns Change When Sash is Closed

SERMACS 2023 copyright @Synthcon LLC T. McKibben

When blocked, fumes can easily exit locations that

span the entire width of the hood (e.g., underneath

the sash or underneath the airfoil).

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Academic Research Hood in Use

SERMACS 2023 copyright @Synthcon LLC T. McKibben

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SERMACS 2023 copyright @Synthcon LLC T. McKibben

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Chemicals/Equipment Simultaneously Elevated off of the Bench Surface

SERMACS 2023 copyright @Synthcon LLC T. McKibben

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Only Small Items Remain on the Bench Surface

SERMACS 2023 copyright @Synthcon LLC T. McKibben

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The View Underneath the MHS – All Portable Obstructions Elevated Off the Bench Surface Except the Rubber Collar & Cords

SERMACS 2023 copyright @Synthcon LLC T. McKibben

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SERMACS 2023 copyright @Synthcon LLC T. McKibben

NO MHS INSTALLED - Air velocity is much lower than the desired set point value. Exit routes are impeded resulting in reduced fume exhaustion. Characterized by TURBULENT, LOW AIR FLOW – BOTTOM BAFFLE EXIT SEVERELY BLOCKED.

MHS CREATES LAMINAR FLOW - CONTINUOUSLY ENHANCED FUME EXHAUSTION – INCREASED SAFETY

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Air Velocity Testing an Analytical Chemistry Fume Hood

SERMACS 2023 copyright @Synthcon LLC T. McKibben

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Provides hundreds of spaces to temporarily hold� equipment.

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SENSOR-CONTROLLED (VAV) HOOD FOCUSES ON

ENERGY EFFICIENCY AT THE EXPENSE OF SAFETY

SLOW BLOWER MOTOR RESPONSE LEADS TO

DELAYED FLUCTUATIONS IN AIR VELOCITIES WHEN

PERSON IS DETECTED OR TIME EXPIRES

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Years of Use and Testing¹

Increases air/fume exhaustion efficiency in all fume hoods tested (both CAV and VAV).
Provides many configuration scenarios for various types of equipment being used.
Used and tested in various types of laboratories in the last six years.

Independent testing lab – 41% increase in performance (MHS installed compared to no MHS installed); 116% increase in performance (fully loaded MHS vs MHS installed and empty); 207% increase in performance (fully loaded MHS installed vs empty hood w/ no MHS). When comparing location of the equipment loads (front, middle, rear) there were performance increases in all regions when using a MHS-equipped fume hood vs a non-equipped fume hood in the same load scenario: [front (66%); middle (177%); and rear (53%)]. For the fume hood not equipped with a MHS a decrease of 22% over all three regions combined relative to the stated certification value was observed.

Forensic lab – 35% increase in performance (with MHS installed and empty compared to MHS not installed); 21% increase in performance (with load as found on MHS compared to empty MHS). *These types of hoods perform more poorly because of the delay in blower speed response when a person is sensed at the hood and their lower velocity in general. The time lag and changing velocity makes them less likely to be at or above their set face velocity.

Chemical production lab - 41% increase in performance (MHS equipped hood vs non-equipped hood).

Academic organic research lab – 63% increase in performance (fully loaded and in use). Note without the MHS installed, this hood’s performance decreased 25% relative to its last certification value.

Academic analytical chemistry lab - 34% increase in performance (when equipped with a MHS vs. an empty hood) and a 44% increase over the last certification value.

¹Most measurements taken over 60 seconds at a rate of 1 measurement per 0.8 seconds (75 measurements averaged).

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Acknowledgements

Thanks to the American Chemical Society and to Samuella Sigmann for the opportunity to speak today.

Contact Information:

Tim McKibben, Manager Synthcon LLC

(719) 429-5376

Website: Forensicdrugstandards.com

Email: Synthcon@drugspectra.com