|Posted on Friday, October 26, 2001 - 04:56 am:||
Photo below, Da Hood.
Below, the blower box and controls. Note clasps.
Below, view of workspace.
Below, HEPA filter and workspace.
Below, Prefilters on top of blower box
Below, Prefilters removed, blower in box.
The two "big" items on your shopping list are the HEPA filter and the motor and blower. The filter is 24x24" and cost right around $300.00 with the shipping. The blower and motor were bought as a kit from Graingers and cost about $150.00 with the shipping. Buying them as a preassembled unit will double the cost. We used Catalog No. 7F735, a 1/5 HP motor and 9.5" squirrel cage blower with housing. In the future we'll probably find that a 1/2 HP motor will better serve us. Be aware that if you're going to use a rheostat to control the fan speed, your motor must be of the split capacitor type.
The casing is made entirely of 3/4" Malmar, which is a pre-covered plywood product.
We are using (3) 1x26x16 fiberglass filters stacked on top of each other as pre-filters. These are used to filter dust and other particulates, saving the HEPA filter for filtering bacteria and fungal spores.
There are two lights in the top of the work area. One is a cool white florescent, the other an Ultra Violet to sterilize the work area before use. The unit has a Malmar cover over the work area to prevent dust from entering as well as to prevent UV radiation from leaking into the room. The cover has two pegs set into the inside edge which match holes on the rim of the workspace. The cover is simply pulled off or pushed on.
The unit is rather large, and though it was built elsewhere, it had to be disassembled and reassembled in the lab..no way would it fit in the door.
The unit casing consists of 2 pieces, a base which contains an air chamber, the filter and the workspace, and the blower-box. The base has a dimension of 41" long x 29.5" wide x 25.5" high. If you note in the first picture below, the front is cut at an angle at the workspace. The length of the unit along the short line is 34.5".
The blower box is 21" long x 29.5" wide x 18.5" high and contains the blower and motor unit as well as a "tray" built into the top for the prefilters.
The actual workspace where work is done is 28" wide x 24" deep. The HEPA filter is just beyond a divider between the workspace and the air chamber. In essence, air is pulled down thru the prefilters in the top of the blower box, forced down into the air chamber below, thru the HEPA filter,and into the workspace.
Lastly, the electronics: Two toggle switches (One for each light) and one rheostat to control the speed of the fan. Appropriately, the white switch is for white light, the black switch is for UV.
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