Parker Aerometric Converter

[mboschm]

I guess the topic explains it pretty much.

Thanks a lot!

[OldGriz]

The 21 does not have a converter.... it has a fixed squeeze bar filler system...

The 45 has a removable converter... and it is not an aerometric...

[Sasha Royale]

I have made this same mistake, too. The flexible metal device, squeezing a bladder,

does not, in itself, make an Aerometric filler. Will someone please explain what

internal function actually makes the mechanism Aerometric ?

 

Thanks.

[OldGriz]

Two descriptions from Richard Binder's website....

 

Anatomy of a Fountain Pen IV: The Parker "51" (Aero-metric Version)

 

Aerometric ~ http://richardspens.com/images/ref/fillers/aero.pngParker's name (colloquially "aerometric") for the system (U. S. Patent Nº 2,612,867) by which its Foto-Fill squeeze-type filling system (introduced in 1948 and illustrated here by a Parker "51") operated. The basis of the Aero-metric ("air-measuring") system is a breather tube that is essentially the full length of the squeeze-filling sac, has a very carefully calibrated inside diameter that is smaller than in other pens' breather tubes, and has a very small hole (also calibrated) in its side near the feed. Whatever differs from this, to the extent of the difference, fails to meet the specifications of Parker's patent for the Aero-metric system and is merely a squeeze-filling pen, not an Aero-metric one. Parker later dropped the Foto-Fill name, using Aero-metric to denominate the filler itself.

Edited November 11, 2012 by OldGriz

[Mike 59]

Hi All, I had never read that description of what 'Aerometric' means.

I thought it was that the breather tube running inside the ink reservoir was a way of getting air above the ink level so that the pressure did not become low, (a vacuum) and cause ink feed problems.

Maybe there is more to it than that, as cartridges have no breather tube yet still work well.

I own one '51' which did not write when I bought it, and I had to push a 22SWG piano wire through the breather tube as it was completely full of dried ink.

It was bought as 'not working', but it just had not been used for many years. Now is working and writes as it should.

[MCameron]

Hi All, I had never read that description of what 'Aerometric' means.

I thought it was that the breather tube running inside the ink reservoir was a way of getting air above the ink level so that the pressure did not become low, (a vacuum) and cause ink feed problems.

Maybe there is more to it than that, as cartridges have no breather tube yet still work well.

I own one '51' which did not write when I bought it, and I had to push a 22SWG piano wire through the breather tube as it was completely full of dried ink.

It was bought as 'not working', but it just had not been used for many years. Now is working and writes as it should.

 

Interesting comment about why the cartridge doesn't have a breather tube yet still works well. I believe, and this is about as scientific as a tall guess, is that the breather tube has more to do with filling the reservoir than it does with writing. As long as the ink level is below the top of the breather tube when you squeeze the sac, air is expelled instead of ink. For writing, all that is necessary to avoid a vacuum lock is that there be air behind the ink. That's why ink cartridges are never completely full--there has to be a little air to create a positive pressure differential between the cartridge and the feed.

 

Like I said, this is all based on a little bit of science and a lot of tall guessing. If anyone can provide a better answer, please do!

[Ernst Bitterman]

All right. This is taken from my own site, and I happily granted myself permission to repost it here:

 

Here’s how the trick {of ink movement} works. When the pen is turned nose down, the feed channel is filled up, blocking air movement. As the ink moves towards the end of the point, this movement of ink out of the reservoir creates the necessary vacuum to hold the whole fluid mass up against gravity, while capillary action ensures that there’s ink at the end of the slit by the time the point touches down. As writing draws more ink out, the interior pressure continues to fall until the point that the resistance of surface tension is no longer enough to keep the high-pressure exterior air from forcing the fluid out of the way in the broader channel of the feed. The narrow channels are a different story, since the closer walls give capillary action more say, and as the high pressure air flows up the feed into the reservoir, ink continues to flow downward, and as the equilibrium is restored between interior and exterior pressure the ink is able to reclose the feed to air.

 

http://dirck.delint.ca/beta/wp-content/uploads/2011/05/drawflow.jpg

 

You're entirely right about...

I believe, and this is about as scientific as a tall guess, is that the breather tube has more to do with filling the reservoir than it does with writing. As long as the ink level is below the top of the breather tube when you squeeze the sac, air is expelled instead of ink.

...because it's easier to push air out of the way than fluid. Edited November 13, 2012 by Ernst Bitterman