How to determine the maximum size of a hole that can keep ink/water stay in an ink-cartridge for fountain pens?
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And the amount of water that the surface tension can hold depends on the depth of the water. If the hole in your cone is small enough to hold the water above it, adding more water will cause it to come through the hole
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Hello mate here is your answer.
To calculate the hole size you need to work out the pressure at the bottom of the cone and equate this to the pressure calculated using the expression above. The pressure at the bottom of the cone depends on the depth of the water, not the total volume of water in the cone. If the depth of water in the cone is hh then the pressure is ρghρgh, where ρρ is the density of the water at the temperature you're working at, and ggis the acceleration due to gravity (≈≈9.81 m/sec22). Equating this to the first expression gives:
ρgh=2γrρgh=2γr
or:
r=2γρghr=2γρgh
For example at STP γ≈7.3×10−2γ≈7.3×10−2N/m and ρ≈ρ≈1000kg/m33, so if the depth of the water in your cone is 10cm the maximum radius of the hole is 0.1mm.
Note that this is the maximum radius for which there is no flow at all. For holes a bit bigger than this the flow may be so slow it's difficult to measure.
Hope it helps you.
To calculate the hole size you need to work out the pressure at the bottom of the cone and equate this to the pressure calculated using the expression above. The pressure at the bottom of the cone depends on the depth of the water, not the total volume of water in the cone. If the depth of water in the cone is hh then the pressure is ρghρgh, where ρρ is the density of the water at the temperature you're working at, and ggis the acceleration due to gravity (≈≈9.81 m/sec22). Equating this to the first expression gives:
ρgh=2γrρgh=2γr
or:
r=2γρghr=2γρgh
For example at STP γ≈7.3×10−2γ≈7.3×10−2N/m and ρ≈ρ≈1000kg/m33, so if the depth of the water in your cone is 10cm the maximum radius of the hole is 0.1mm.
Note that this is the maximum radius for which there is no flow at all. For holes a bit bigger than this the flow may be so slow it's difficult to measure.
Hope it helps you.
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