What I Want to Do
Building on a conversation that @NShapiro, @Warren, and @DanBeavers and I have been having in Nick's note on his DIY Formaldehyde testing kit and our desire to lower the barriers to testing by mailing around air pumps in our lending library.
My goals are three-fold: make the kit robust and easily shippable, prevent user error with automatic shutoff, and (potentially) remove the most expensive component, the flow control valve.
My additions
In addition to @nshapiro's parts list I've added:
- an arcade-style big red button
- a timed relay
- a hard case (Seahorse SE300)
- a laser-cut 1/4" thick case panel file (the red lines are cut lines, blue are markings)
The panel is held on with 3/4" long #4 screws, the relay is held in place with 1" #4 bolts, and the formaldehyde tube is held in place with a 3/8" screw hook.
Unfinished bits:
- there is a place for a 3" x 5" info card but no card. *there should be a thermometer and hygrometer in the lower right
- there is no flow-restrictor on the intake valve, as I discussed in @nshapiro's note's comments
- Ionically, the material I had around to laser cut was MDF, a material well-known to off-gas formaldehyde. I'll find something else soon.
5 Comments
This looks great! What does it weigh? I wonder if loosing the blue plastic shell on the pump would lighten the load in any more cost-efficient way.
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To be a little more precise about "(potentially) remove the most expensive component, the flow control valve." I have not priced them but an aquarium pump control valve or a hardware store needle valve should control the flow cheaply. The problem is flowing 9 L of air thru the tube in roughly 30 minutes in an accurate, inexpensive, reliable, and easy manner.
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