need to fill a pipe half full

I'm experimenting with heat pipes. I want to fill a foot of 1/4" copper pipe half full of freon. I don't have any way to recapture the freon, so I can't just over fill it and vent it till it gets to the right level. If it works I'll be building a bunch of 'em.
Way too many pipes hanging off the thing to do it by weight. Only thing I can think to do is an ice bath on the bottom half and wait.
Ideas how to determine the liquid level within half an inch or so while still hooked up to the manifold?
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Calculate the internal volume of the heat pipe. (I'm assuming you want it 1/2 full of liquid) Using a sealed glass charging cylinder, bleed just enough refrigerant from your supply to put liquid up to the required level in the charging cylinder. Evacuate all the air from the heat pipe. Transfer the refrigerant into the heat pipe. Seal the charging port.
There is no need to vent ANY refrigerant into the atmosphere...(and it would be illegal to do so.. not to mention foolish.)
You need to invest in a refrigerant handlers license.. and a refrigerant recycler machine. They arn't that expensive.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.