Date: 28/07/2022
Categories: let's build a lab

laminar flow-hood / biosafety cabinet

Next, I had to take place where all the biology/genetics stuff will be happening in a clean, non-contaminated area. This is the tougher one to solve.

I had a few options:

  1. using a clean tent

    + could be sterile and work best for keeping sterile, if the ventilation system of the closed tent could incorporate HEPA filtering
    + easy to build
    + cheapest variant

    – might need a decontamination chamber added, also the process of going in/ out of a tent while keeping the hygiene of person in between the entrance
    – not other people friendly (you just can’t demonstrate/show it to another person, other than camera and display outside of the tent, which decreases joy of both parties involved


  2. building a laminar flow cabinet (either „desktop“ box one, or a fume-hood-like structure with HEPA)

    + construction is almost the same as in fume-hood I have already just built
    + can have both parties involved feel the joy of not staring into displays

    – fumes and stuff goes into your face, so you would need to work with non-breathable chemicals inside the fume-hood, leading to multiple transfers between boxes


  3. biosafety cabinet, class II A2 (winner)

    after more internet search, this one has it all for me:

    + biosafety cabinets do not blow fumes/ contaminants into your face
    + can be used in different modes
    + has HEPA

    – HEPA has to be replaced every 6 months of use, can’t be cleaned
    – ?

build

Firstly, I opted for commercial design brochures and noted the dimensions and ratios. This is what I came up with:

biosafety cabinet (azure colored box is a HEPA filter)

The design has changed a bit later and I have also realized that I need to switch to Fusion360 software so it could communicate with my CNC machine better because I will be needing it this time for sure, as cutting precise angles with hand for me is always not as precise as to satisfy my compulsive part.

final design:

final design in fusion360

photos from the build process:

cnc-ing the side-profile
precision angles!
removable HEPA holder
HEPA double sealing
HEPA
one intake to filter, other 30% out
grills
a velvet sealing for a glass
axial ventilator flexible harness with a sealing
counterweigths for sliding glass and vent recycle system



caviats & challenges:

  1. everything must be sealed
  2. air path-way is more complicated, in this design, not all air is recycled, but 30% goes out (as you can have greater „sucking“ power at the bottom but still not push too much into the filter to destroy it, this also removes fumes instead of them just cycling

finished result:

how it works

a few diagrams images to explain basic idea can explain it better than I could:

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