How To Design and Build A Laminar Flow Hood: Part 1 - Design
Building a Laminar Flow Hood for Growing Mushrooms
In this video, Tony from Fresh Cap Mushrooms shows the process of building and designing a laminar flow hood for growing mushrooms. He explains what a laminar flow hood is and why it's important, breaks down the three basic steps to building one, and provides tips on choosing an adequate filter.
What is a Laminar Flow Hood?
- A laminar flow hood is essentially a big wooden box with a HEPA filter in the front and a squirrel cage blower fan on top.
- The purpose of the laminar flow hood is to blow air through the filter and provide a clean stream of air with no contaminants that you can work in front of during mycological work.
Three Basic Steps to Building a Laminar Flow Hood
- Choosing an Adequate Filter
- Choose an adequate filter size based on your needs.
- Find HEPA filters specially designed for laminar flow with efficiency ratings of at least 99.99% at 0.3 micron.
- Keep in mind pressure drop ratings when selecting filters.
- Finding a Blower Fan
- Find a blower fan strong enough to push air through your chosen filter at the specified rate.
- Building the Box
- Build the wooden box to house your HEPA filter and blower fan.
- Wire up your components properly.
Tips for Choosing an Adequate Filter
- Consider getting at least a 24 inch by 24 inch or even 24 inch by 48 inch filter if you plan on doing inoculations or working with mushroom grow bags.
- Choose HEPA filters specially designed for laminar flow with efficiency ratings of at least 99.99% at 0.3 micron.
- Keep in mind pressure drop ratings when selecting filters and add on about 0.1 to 0.3 inches of water gauge for the pre-filter.
Conclusion
Building a laminar flow hood can be broken down into three basic steps: choosing an adequate filter, finding a blower fan, and building the box. When selecting a filter, consider size, efficiency rating, and pressure drop rating. With these tips in mind, you can build your own laminar flow hood for growing mushrooms and improve your mycological work.
Sizing the Fan
In this section, the speaker explains how to size a fan for a laminar flow hood.
Calculating Volumetric Flow Rate
- To calculate the volumetric flow rate of air needed for a laminar flow hood, multiply the area of your filter by 100 feet per minute.
- For example, if your filter is 24 inches by 48 inches (about 8 square feet), you need a fan that can provide 800 cubic feet per minute (CFM) of air.
Finding the Right Fan
- The pressure drop of your filter affects the flow rate of your fan. You need to find a fan curve from the manufacturer to determine what flow rate you'll get at a specific pressure.
- Look at different fans and find one that fits your needs.
- The speaker uses a Dayton one TD tube fan for his laminar flow hood.
Assembling the Fan
In this section, the speaker explains how to assemble and wire up a blower fan for use in a laminar flow hood.
Wiring and Mounting
- Blower fans typically don't come wired or with mounting hardware.
- You'll need to do some electrical work to wire it up with a switch and plug so you can use it.
- Some blowers have flanges that make them easy to mount on top of your cabinet, but others won't have any mounting hardware at all.
Conclusion
In this section, the speaker concludes his video series on building a laminar flow hood.
Final Thoughts
- With all necessary components assembled, constructing an actual working laminar flow hood is straightforward.
- The speaker will cover materials used and construction in his next video.