Opening a vacuum port.

[Justincase]

I have a Vacuum desiccator.
But it seems no one has ever opened up its port.
It has a nice threaded cap and fitting.
But the glass was blown and no hole made to allow for a port and valve to be fitted.
I am unsure whether to use a diamond drill to try and grind an opening which would leave some stress points.
Or whether to use an Oxigen torch to melt a small hole.
How would you approach such a job?

 

[Justincase]

I still have not decided how to do this.
Tempted to try a small chisel and hammer.
Has anyone opened up one of these?

 

[Martijn]

Drill it with a diamond tip drill bit under water.
I've made holes in aquaruim glass like that. Support the bottom side of the glass with a piece of wood to prevent the last edge from shattering too much.
You can make a guide for the drill from a piece of wood with a large hole that slides exactly over the neck and drill out the center guide hole to the right size you want to drill.
Trickle feeding water into the guide would be enough to lubricate and keep glass splinters from flying around.
Martijn.

 

[Justincase]

Yes I have been thinking about drilling it.
I had not thought about doing it underwater.
Lab glass is one of those things that when you know, you know.
There will be an old way that once tried works 100% is simple and seems very obvious once you know it works.
The problem is when you only have one unit and several options, no room for experiment.
I remember being fascinated the first time My Chemistry teacher cut a simple glass tube and made a pipette, one small scratch, and you get a clean break.
An expensive bit of glass to shatter. :lol:

 

[butcher]

just a thought instead of drilling the glass, can you make a thick gasket, with a vacuum port included in the construction of the gasket materials.

 

[Justincase]

just a thought instead of drilling the glass, can you make a thick gasket, with a vacuum port included in the construction of the gasket materials.

I suppose you could cast a thick latex or other rubber like gasket with a port built in, The problem would be the more robust and chemically resistant a material you used, the more demanding the production.
This has been blown and deliberately manufactured with a nice neat screw thread and cap.
It seems strange that they would then ship it with the port obscured by a thin bit of glass.
Do you think this is standard with such equipment, or an oversight in quality control?

 

[butcher]

Diamond drill bits can make drilling glass fairly easy.

I have no idea about the piece of lab glass equipment you have, could the thin glass be something similar to a safety relief valve breaking on over vacuum something similar to the weighted safety on a pressure vessel pert, or the soft metal plugs that melt under heat or blow upon overpressure f the vessel?

Could these be used with a center section of glass insert with a port? In another thread of the topic of lab glass there is a picture of something similar, a round glass cylinder made to seal on both ends with a side glass port connection?

 

[Justincase]

It appears to be a totally standard vacuum desiccator as you can buy of the shelf.
Except of Corse the port has not been drilled.
I think it was left sealed, so you could use it as a standalone desiccator with a descant, but with the option to upgrade to a vacuum pump if you wanted.
I bought it second hand as the person who had it had used it chose a desiccating agent which seemed to absorb so much of the internal moisture and other volatiles as to form a vacuum.
He had tried for several years to get the two bits to part with no success.
When I got it they slid quite readily apart with a good bit of lateral force, he had been pulling all the time.

 

[Lou]

Not all desiccators are made for vacuum use.

You can use that one with a desiccant and store things needing to be dry for analytical work (porcelain ware, Gooch crucibles).

Best desiccant probably is P4O10.

 

[Justincase]

Not all desiccators are made for vacuum use.

You can use that one with a desiccant and store things needing to be dry for analytical work (porcelain ware, Gooch crucibles).

Best desiccant probably is P4O10.

I have another one with a Knob on top, I use it to keep my pawn-broker test acids in.
But this one quite clearly was intended to have a port fitted.
I was hoping someone would say simply scoring and tapping out would work. That is how most other glass is cut.
But I will look for a diamond drill.
Maybe a local business would have a cutting gig for glass.
Thanks.
J

 

[butcher]

You can get different sizes of diamond bits made to drill holes.
You could also take it to your local glass dealers who cut and drill glass for a living.