Respirometer cap
20mm diameter
The main limitation of such a small respirometer is ensuring that the cap openings are wide enough to allow enough water flow without compromising the recirculation pump. At these small diameters, physics and drag really start to play against you. Keeping openings wide enough is a challenge because we have very little space to work with. However, with some clever sheet stacking tricks, we can increase our working space considerably, as you will see below.
Materials required
Before looking at the list below, it is important for you to consider that the parts you have access to will change depending on where you are in the world. I designed these while in Canada, where imperial units prevail. Depending on where you are, you can adapt the schematics to fit the commercial parts available to you.
- Access to a laser cutter
- 1/8in (3 mm) acrylic sheet
- 2/8in (6 mm) acrylic sheet
- 3/16in (4.7 mm) plywood sheet
- 2× straight connectors (3/16in barb × 1/8in NPT)
- 2× 90° elbow connectors (3/16in barb × 1/8in NPT)
- NPT thread tap matching the connectors
- 3 mm × >3 cm nylon screws
- 3 mm thread tap
- ¾ in (20 mm) ID clear PVC tube
- Viton O-rings (OD just under the ID of the clear PVC tube)
- Clamps
- Masking tape
- sand paper