Selecting a Workspace
Good Candidate Workspaces
Places that make good workspaces for supercritical drying include:
- A high school or college chemistry lab (best)
- An industrial floor (good)
- A garage, ideally with a temperature between 50 and 80°F (good)
- A basement with lots of space (okay)
Your workspace should not be outside–it should be sheltered. The supercritical dryer has components which could be damaged by weathering, rain, and snow.
Ventilation
The most important feature your workspace should have is adequate ventilation. You will be venting a lot of CO2 when you do flushes prior to supercritical drying and you will want to make sure the vented gas is pulled away adequately. Carbon dioxide can asphyxiate if it is not properly vented away.
Consider what would happen if an entire tankful of CO2 were to vent all at once (either 20 lbs. or 50 lbs. of CO2, depending on how big of a tank you select) and whether or not your workspace would provide adequate ventilation for that much gas.
In an industrial setting in the United States there are OSHA guidelines for calculating airflow exchange that must be observed.
Lighting
You’ll want to make sure that you can see everything clearly in your workspace, as attention to fine details such as looking for detritus on pipe threads, monitoring gauges, and inspecting for cracks will be important.
Sturdy Floor
A sturdy floor is necessary to ensure the supercritical dryer is not knocked over, especially while it’s pressurized. Additionally, your supercritical dryer will need to get picked up and positioned from time to time and so a floor that can withstand scuffs from metal is better. Cement or flat title are good.
Delivering and Storing Gas Tanks
Last but definitely not least, you will need to consider if it is possible to deliver gas cylinders into and out of your workspace and where you can store and secure them once you deliver them. If your workspace is up or down any stairs, remember you will have to have a way of lifting the tank up and down these stairs, which is generally not recommended. If you do have to carry a tank up or down stairs, you’ll have to settle for a “20-pound” tank, which contains 20 lbs. of liquid CO2 but weighs about 45 lbs.
If working in a garage, be aware that the outside temperature will affect your process since the vapor pressure of the CO2 inside the tank changes with temperature. Although there’s no risk storing the tank where the temperature can fluctuate, it will complicate the supercritical drying to operate it in such a workspace.
Wherever your workspace is, make sure you have a place you can secure the gas tank from tipping over.