Pop bottle rainfall gauge
A rainfall gauge needs to collect rainfall in an open cylinder with a sharp edge. The water collected in this cylinder falls into a smaller collection cylinder below. The design should limit evaporation from the collection cylinder. The greater the difference in the cross-sectional area between the top and bottom cylinder, the greater the accuracy in the measurement. The pop bottle rain gauge provides about a 15 to 1 ratio between top and collection cylinders.
Materials
1 @ 1 liter clear plastic pop bottle
1 @ 3 inch length of 4 inch PVC sewer pipe
1@ 4 inch PVC end cap
1 @ flat bottom clear ¾ inch pill bottle
Instructions
A rainfall gauge needs to collect rainfall in an open cylinder with a sharp edge. The water collected in this cylinder falls into a smaller collection cylinder below. The design should limit evaporation from the collection cylinder. The greater the difference in the cross-sectional area between the top and bottom cylinder, the greater the accuracy in the measurement. The pop bottle rain gauge provides about a 15 to 1 ratio between top and collection cylinders.
Materials
1 @ 1 liter clear plastic pop bottle
1 @ 3 inch length of 4 inch PVC sewer pipe
1@ 4 inch PVC end cap
1 @ flat bottom clear ¾ inch pill bottle
Instructions
- Cut the barrel part of the pop bottle away from the top and bottom. Keep both the barrel and top.
- Bevel an end of the 4” PVC pipe so that there is a sharp edge.
- Insert and glue with PVC solvent the bottom end of the PVC into the remaining rim on the top. This makes a funnel with a PVC top with a sharp lip.
- Glue the end cap onto the pop bottle barrel. This makes the bottom of the collection unit.
- Set the pill bottle in the collection unit under the funnel part of the collection unit.
- Calibrate the unit by first measuring and calculating the cross sectional area both the top and bottom cylinders. This gives the ratio between top and bottom collection units. If the ratio was 20 to 1, then 1 cc of water poured in the top would rise 20 times higher in the bottom collection cylinder. The calibrations should be marked on the pill bottle.
- If the bottle overflows, then repeatedly measure, empty and refill from the larger collection base.