I need to connect a 3mm inside-diameter tube from a solenoid valve to a plastic box. The box wall thickness is 4.5mm. The purpose is to empty water in the box when needed.
How should I connect it so that it is water-tight (very low pressure - around 70mm water depth)?
The photo shows the valve and the plastic box.
If you don't care it being a little flimsy and just want quick, and the plastic is not too brittle:
Use a barbed fitting with a straight thread on the outside, e.g. #10-32 of M5x.8 (these sizes happen to be interchangable), and a sealant.
SUMMARY:
drill 4.2mm (work up size in small increments to avoid cracking)
tap hole M5x.8 (or #10-32) (with great care, again b/c cracking)
install fitting M5x.8 (or #10-32) x barb
(type intended for 3mm (or 1/8" = 3.2mm) tube)
add silicone sealant (but make sure gasket is not silicone)
(may need to abrade and clean surface to get sealant to stick well)
Illustration of fitting type ... you can probably find something for $1 if you try
If the plastic is brittle, as is pretty common for optically clear materials, a glue-in barb fitting or a bulkhead type retained by a nut on the far side, should be used instead.
If you don't want to drill a hole on the box and mess around with nozzles and sealants, a solution would be to siphon water like
The only difference is that that valve is going to be at the bottom side.
The only "problem" is that you need to fill the hose. A common solution to that is
