Category: 24x24 flow hood design

A laminar flow hood is a piece of equipment which makes sterile working procedures in mushroom cultivation easier and reliable. A flow hood consists of a coarse pre-filter, a blower and a very fine filter the so called HEPA High Efficiency Particulate Air filter which filters particles from the air to a high degree.

This makes the air coming out of the HEPA filter nearly sterile which allows doing transfers in this stream of sterile air without worrying about contaminants entering from the air and contaminating the cultures.

24x24 flow hood design

The HEPA filter size depends on how big you want to have your working space. The smallest filter size you can reasonably use for home scale cultivation is 1ft x 1ft, better though 1ft x 2ft or 2ft x 2ft if you are going to inoculate filter bags.

USA Filter search web site. Once you decided on the size of the HEPA filter, you have to match a suitable blower to this particular filter. This is a very important step, so make sure to study the directions thoroughly. Every filter has a "resistance" when air blows through it at a certain speed, this resistance is called the "static pressure". Press your hand against your mouth. Now try to blow through it.

Dependant on how firm you press it against your mouth, you will have some difficulties blowing air out and you will feel some resistance, this is the static pressure. Every filter has a different static pressure at the working point. The working point is where the amount of the air flowing through the filter is sufficient to meet the requirement of the laminar flow.

The static pressure is expressed in inch of water column in the English units, a typical value would be 1", the SI unit for pressure is Pa Pascal. Each filter has a data sheet consult the manufacturer if this is not the case with your filter where the static pressure at the working point is entered. Before the air enters the blower it is usually pre-filtered by a furnace filter around 1" 2. It can be assumed that the static pressure for this prefilter at the working point is around 0.

According to Stamets Paul Stamets and J. Chilton: The Mushroom Cultivator p. Determining the correct blower for a filter consists of several steps:.

Find out the area of your filter by multiplying the width and the hight in feet for instance the smallest reasonably usable filter would be 2ft x 1ft. So if you use the above filter with 1" Pa static pressure and a furnace prefilter with a static pressure of 0. Each blower has a data sheet consult the manufacturer if this is not the case with your blower where the correlation between the volumetric flow and the static pressure is represented by a graph or table.

Here is such a set of curves for 4 blowers numbered NOTE: Each model of a blower has his own characteristic curve. This chart shows the curves for 4 different particular models of axial duct blowers.Click any link below and If you've done any checking into hoods, you know most places charge an arm and a leg for them.

These plans are for a 12"x24" Flow Hood like the one pictured below. The two largest costs are the fan blower and the HEPA filter. If you can get a hold of a used squirrel cage style blower that would be perfect.

Laminar Flow Hood

These are used in furnaces and industrial applications mostly. If you know anyone in HVAC they can get you one for practically nothing.

Otherwise, a good place is HERE. You will need at least a cfm blower to power a 12"x24" HEPA filter figuring. Skill saw or table saw jig saw even, anything to make a straight cut. If you have a Lowe's, Menard, Home Depot or any other large home store, check there.

Most of these places have pre-cut wood in their lumber sections that work perfect for this project with very minimal cutting. If you have access to a saw, then it's way cheaper to buy a large sheet and cut it yourself. To get started, you need to cut all the pieces for the box itself. When you have these pcs. It helps to have someone to hold pcs.

Drill pilot holes for all screws so as not to split the wood. Put together sides, top and bottom first. Don't tighten the screws all the way tight, you may need some room to slide the back in. When the sides, top and bottom are together, slide the back in either end, it doesn't matter yet. Before you screw the back in, tighten the rest of the screws holding the box together.

Make sure it's lined up flush and screw it in place. The purpose of the 1x1's is to create a flange 6" deep to push the filter against so a tight seal is created.

Once the box is complete and the flange is in, it's time to cut a hole in the top for the blower to push air through. Measure the hole in your blower, and draw it out on the top of your hood about 1" from the back a bit more if your blower needs. Center it from side to side.

Then cut this out. Once the hole for the blower is cut, you need to clean out any sawdust real well. Next, you need to seal all the seams on the inside of the box.

24x24 flow hood design

Use your silicone sealant to run a bead on every seam. Then smooth it with your finger. Once the box is sealed, you can put on your blower. Put a small bead of silicone around the edge of the hole for the blower. Place the blower over the hole and screw it in place it helps to center blower before silicone, then mark where the holes need to be and predrilled.

After the blower is mounted, you can plug it in and it'll blow out any stuff dust, etc. A cheap way to set this up, is to get a six plug power strip, and mount it in front of the blower on top of the hood. Lastly, you need to cut your trim pieces so that you have 4 pcs. Drill pilot holes through your trim pcs.One equipment I wanted most but beyond my reach was a Laminar Flow Hood. A Laminar Flow Hood provides a small sterile work area, where you can carry out all your culture works without the risk of contamination, simply by flowing completely purified air at a specified rate.

Laminar Flow Hoods

However, the cost of the simplest form of the equipment is very prohibitive The alternative? Construct your own equipment In a horizontal type, the purified air is blown from the back and moves towards the front of the working area. This Instructable will provide you step-by-step instructions on how to build your own portable Laminar Flow Hood without any compromise on standard specifications. Did you use this instructable in your classroom?

Add a Teacher Note to share how you incorporated it into your lesson. I could lay my hands on a slightly larger sized HEPA filter used in window air conditioners. I have removed it from the original frame, reduced it to 29 centimeters by 15 centimeters size and mounted the filter to frame work made of Plexiglas. This frame work is further fixed to the center of another frame of size 40 centimeters by 25 centimeters by cutting out the center portion to the required size.

This frame is also made from Plexiglas. You can see the entire assembly of the HEPA filter in the first picture. Plexiglas comes with protective covering on both sides to prevent any scratches. Do not remove these protecting covering while working with Plexiglas.

As the main body is completed with press board, we can easily measure the top and front cover portions of the flow chamber. Cut the Plexiglas to the required sizes. Here, I have cut the top cover in to two pieces, one covering the air chamber and another for the work area. Do not fix them to the body Remove this covering only when you are satisfied that your work will not cause any damage to the Plexiglas surface. If you already won a good quality vacuum cleaner, then you will have to spend about Rupees only for the other materials.

Please offer your comments and suggestions for any improvement in the above design. Sorry but this is a total waste of time and money. For laminar flow you need the proper hepa filter matched with the proper blower to achieve cfm. Anything else wont proved true lamiar flow. Also pressurized glove boxes defeat the purpose and increase contaminants.Potential hazardous and polluting applications requires special solutions.

24x24 flow hood design

Always check local regulations before design. Capture velocity - v 1 - for an exhaust hood can be estimated with the empirical equation. Required air volume flow for a exhaust hood with circumference 3 m located 1.

The units don't match since the equation is empirical a result of experiments. Add standard and customized parametric components - like flange beams, lumbers, piping, stairs and more - to your Sketchup model with the Engineering ToolBox - SketchUp Extension - enabled for use with the amazing, fun and free SketchUp Make and SketchUp Pro.

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AddThis use cookies for handling links to social media. Please read AddThis Privacy for more information. If you want to promote your products or services in the Engineering ToolBox - please use Google Adwords. Exhaust Hoods Sizing exhaust hoods - air volume flow and capture velocities - online exhaust hood calculator Sponsored Links. Exhaust hoods are essential in kitchens, laboratories and industrial application for removing fumes mists vapors aerosols particulates hazardous substances polluting contaminants before they "escapes" to from the surrounding air.

In general for an exhaust hood to be efficient the height - y - should not exceed 1. Exhaust Hood with Side Walls The exhaust hood efficiency can be further improved by adding side walls.

Privacy We don't collect information from our users. Citation This page can be cited as Engineering ToolBox, Exhaust Hoods. Modify access date. Scientific Online Calculator. Make Shortcut to Home Screen?The laminar flow hood provides an aseptic work area while allowing the containment of infectious splashes or aerosols generated by many microbiological procedures. Note: You clicked on an external link, which has been disabled in order to keep your shopping session open.

Laminar Flow Hood

Search Thermo Fisher Scientific. Search All. Laminar Flow Hood. See Navigation. Classes of Laminar Flow Hoods. Class I laminar flow hoods offer significant levels of protection to laboratory personnel and to the environment when used with good microbiological techniques, but they do not provide cultures protection from contamination. They are similar in design and air flow characteristics to chemical fume hoods. Class II laminar flow hoods are designed for work involving BSL-1, 2, and 3 materials, and they also provide an aseptic environment necessary for cell culture experiments.

A Class II biosafety cabinet should be used for handling potentially hazardous materials e. Class III biosafety cabinets are gas-tight, and they provide the highest attainable level of protection to personnel and the environment.

Cell Culture Hood Layout. A cell culture hood should be large enough to be used by one person at a time, be easily cleaned inside and outside, have adequate lighting, and be comfortable to use without requiring awkward positions. Keep the work space in the cell culture hood clean and uncluttered, and keep everything in your direct line of sight.

The arrangement of items within the cell culture hood usually adheres to the following right-handed convention, which can be modified to include additional items used in specific applications. A wide, clear work space in the center with your cell culture vessels Pipettor in the front right, where it can be reached easily Reagents and media in the rear right to allow easy pipetting Tube rack in the rear middle holding additional reagents Small container in the rear left to hold liquid waste.

How to Make a Clean Air Enclosure (for HDD repair etc)

Thermo Fisher Scientific Inc. Laminar flow hoods protect the working environment from dust and other airborn contaminants by maintaining a constant, unidirectional flow of HEPA-filtered air over the work area. The flow can be horizontalblowing parallel to the work surface, or it can be verticalblowing from the top of the cabinet onto the work surface.

Depending on its design, a horizontal flow hood provides protection to the culture if the air flowing towards the user or to the user if the air is drawn in through the front of the cabinet by negative air pressure inside.

Vertical flow hoodson the other hand, provide significant protection to the user and the cell culture. These devices only provide product protection.

Portable Laminar Flow Hood

Clean benches can be used for certain clean activities, such as the dust-free assembly of sterile equipment or electronic devices, and they should never be used when handling cell culture materials or drug formulations, or when manipulating potentially infectious materials.

Figure 2. Left-handed workers may switch the positions of the items laid out on the work surface.Keeping mold spores, bacteria, and other nastiness out of your mushroom spawn is a constant fight for the cultivator. You could use a glove box with a pretty high rate of success, but anyone who wants to get serious about growing mushrooms needs to consider using a laminar flow bench. Having a clean stream of air to work in is way more comfortable and much easier to use than an awkward glove box.

A properly constructed laminar flow bench can allow for ultra clean laboratory conditions even in a not so clean environment such as your kitchen or basement, greatly increasing chances of success for a home cultivator.

The idea is to provide a smooth and constant flow of clean air over a work bench. Working within this flow using proper techniques should allow for petri dishes and spawn jars to be open without risking mold spores or other contaminants getting in.

The end result is easier and more successful inoculations, grain to grain transfers and agar work. The main consideration when choosing a filter is size.

Bigger filters, however, require a more powerful and more expensive fan to push through the required amount of air. You want the filter to have an efficiency rating of at least This means that the filter will stop Another consideration when choosing a filter is the static pressure.

Most HEPA filters will have between 0. This is simply a measure of the amount of friction between the filter media and the air being pushed through the filter. You will also want to add a pre-filter, which is cheaper and easier to replace than a HEPA and will stop big particles from clogging up your filter.

It is generally installed at the intake of the blower fan. You can use cut-to-fit vent filters to customize the pre-filter to the size you need. This pre-filter will have a static pressure of 0. This is actually quite a lot of static pressure and requires an adequately sized fan in order to provide a sufficient stream of clean air over your work area.

The information for both the efficiency and the static pressure of the filter should be provided by the manufacturer. You are unlikely to find this type of HEPA filter locally, however, there are many sources online, offering a number of different sizes. NOTE : Make sure you get a proper deep seated filter, such as the ones listed above in order to get smooth laminar flow through the face of the filter.

Laminar flow hoods typically use a squirrel cage type blower fan that is mounted on top of the hood. These fans are rated based on the volume of air that they produce at zero static pressure in cubic feet per minute CFM. As the static pressure increases, the amount of air the fan can produce decreases. For mushroom cultivation, it is generally suggested that the stream of clean air should flow over the workbench at a speed of feet per minute.Easy-to-read, question-and-answer fact sheets covering a wide range of workplace health and safety topics, from hazards to diseases to ergonomics to workplace promotion.

Download the free OSH Answers app. Search all fact sheets:. This document is part of a series of documents on industrial ventilation, and provides general information about hoods. A hood - correctly called a local exhaust hood - is the point where contaminated air is drawn into the ventilation system.

The sizes and shapes of hoods are designed for specific tasks or situations. The air speed velocity at the hood opening and inside the hood must be enough to catch or capture and carry the air contaminants. To be most effective, the hood should surround or enclose the source of contaminant or be placed as close to the source as possible. Enclosing hoods, or "fume" hoods, are hoods surrounding the process or point where the contaminants are generated.

Examples of completely enclosed hoods all sides enclosed are glove boxes and grinder hoods. Examples of partially enclosed two or three sides enclosed hoods are laboratory hoods or paint spray booths. The enclosing hood is preferred whenever possible. These hoods are designed to "receive" or catch the emissions from a source that has some initial velocity or movement. For example, a type of receiving hood called a canopy hood receives hot rising air and gases as shown in Figure 2.

An example is a canopy hood located over a melting furnace. These hoods are located next to an emission source without surrounding enclosing it. Examples are a rectangular hood along the edge of a tank as shown in Figure 3 or a hood on a welding or grinding bench table figure 4 or a downdraft hood for hand grinding bench figure 5. The ventilation system removes contaminants by "pulling" the air and the contaminant into the exhaust hood and away from the worker or the source.

Airflow toward the hood opening must be fast or high enough to "catch and transport" the contaminant until it reaches the hood and ducts. The required air speed is called the "capture velocity".

Any air motion outside of the hood and surrounding area may affect how the air flows into the hood. The ventilation system will require a higher airflow speed to overcome air disturbances. As much as possible, the other sources of air motion should be minimized or eliminated for the ventilation system to work effectively.