Why do eyewash bottles squirt their contents?

Just a reminder that a weep hole or loose cap for flammable vapours might be hazardous.

PS But then there already is the original outlet ........doh.
 
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Tozguy said:
Just a reminder that a weep hole or loose cap for flammable vapours might be hazardous.

Best not to attach them directly to the furnace cabinet, But many of us are really just a bunch of irresponsible hooligans at heart. Cheers, Mike
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Boswell said:
Not a big deal but I think the cause is less temperature cycling than air pressure changes. This configuration of a closed bottle with a tube to the bottom of the bottle, is essentially a barometer. If the vertical squirt tube is clear, you can see the changes in air pressure. The solution is the same , loosen the cap or like MrWhoopee says, add a small weep hole to allow the air pressure in the bottle to equalize with ambient air pressure.
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Actually there is a third thing at work here a lot of people don't consider. But I will get to that in a minute.

Temperature causes air pressure to vary by about 1/3 over the range of normal outdoor air temps. So the temperature cycling present in an unheated shop over the winter will work a squeeze bottle like a pump. The fuller the bottle is the less pronounced this effect will be because the volume of air is reduced. So, if you fill your bottles to the top they will not weep as much.

Air pressure variation as a result of barometric pressure by comparison is far less of an issue. Typical variation in pressure is less than 3% between high and low absent some major weather system like a tornado or hurricane. And the period of those changes is much longer than 1 day as the temperature changes from day to night and with the seasons.

The 3rd thing I mentioned is the effect of vapor pressure differences between the air in the bottle and the air in the atmosphere. If you seal the bottle up when the humidity is high the amount of water vapor in the air will be higher while the pressure will be lower. In effect it is even less than the barometric pressure only. But any change in humidity will have an effect on the volume in the container and will also push oil out.

To prevent the temperature variation from pumping the bottles the volume of air needs to be minimized and the tube needs to be full of air to the bottom of the bottle. A larger diameter tube will help too with a nozzle shaped into the end to give you the size orifice at the end of the tube to give the flow you want.
 
I realize solvents could eat the plastic, but I don't think that's happening here. I did try loosening the caps, and they still pumped anyway, but not as bad. I'll try adding weep holes. At least I'm reassured now that I'm not crazy, and this is a thing that happens.
 
You are definitely not crazy, at least not more so than the rest of us.
 
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