Author Options:

HEPA flow hood? How to build one for my green house. I don't want contaminants getting in at research. Answered



8 years ago

Funnily enough, we are building one at work at the moment, into a laminar air flow cabinet. We need to assemble parts that must have no dust.contamination at all.

You'll need a good fan, one that is happy to blow into a pressure restriction. That means you need a "snail fan", probably, if its like ours, about 400Watts.

We bought the filters from a supplier in the UK, where we are. They consist of a pre-filter, and then the HEPA unit.

You want a filter the same length as your proposed cab, we made ours around 1metre (39") long. There is a perspex panel over most of the front, leaving a 150mm gap to put your hands in.

Air enters the top of the cab, and gently wafts from the slot.



8 years ago

If you wish to build your own I suggest you get a working understanding of the use of the Bernoulli Equations. They will aid you in understanding and overcoming your pressure losses and required ducting for assmbling the filter and selecting a fan.

Aside from that you will probably want to learn how to seal things to make them airtight as even the slightest leak around the filter at inlet will introduce contaminants into your enclosure.

The manufacturer of whatever filter you use should be able to supply you with values for pressure drop of both an empty and loaded filter. You should aim to calculate for a half loaded filter as using fully loaded ones is both extremely inefficient and can put a very heavy load on your fan.