I hadn’t given breather tubes a second thought until I unexpectedly ran into one in a 1951 Park Parkette. I got to thinking “what are breather tubes and why are they only in some pens?”
What is a breather tube you ask? Welp, it is added to a filling system whose mechanism will not completely fill the ink reservoir with one cycle of compression and vacuum.
The breather tube is a thin tube inserted into a hole in the back end of the feed and extends into the ink reservoir; it permits complete filling in pens that require multiple operations of the filling mechanism.
They also control the airflow within the barrel, thus immediately balancing the pressure of the air inside the ink reservoir with that of the external air, because the breather tube provides a way for air to transition between inside and outside, thus reducing or eliminating the tendency of leakage at high altitudes, sometimes!
What? How does it work?
When a filler mechanism is engaged, it pushes air out of the reservoir up the ink channel in the feed and out through the breather hole and slit in the nib. The nib of the pen is submerged in ink, as the compression stage ends, a vacuum is created and the evacuated air is replaced with the ink drawn up through the same channel in the feed.
Breather tubes require modification to the feed. A hole is drilled into the reservoir end of the feed, in to which the breather tube is inserted. Perpendicular, a “blowhole” is added via the ink channel or the dorsal side of the feed connecting with the breather tube hole.
A breather tube (26), effectively extends the ink channel deep into the reservoir. Thus, when the filler mechanism is engaged, the air is forced out through the tube and the “blowhole” in the feed (16). The vacuum draws ink up the ink channel into the blowhole. As the blowhole is attached to the breather tube, the distance ink travels is farther so a better vacuum is created. As ink exits the breather tube it fills the reservoir while maintaining a vacuum. Once the ink level in the reservoir reaches the end of the breather tube (A), the vacuum is equalized and the pen is “full.”
This sounds great – right, well it does come with a significant aggravation. The breather tube makes it difficult to completely empty the pen thus cleaning the reservoir is problematic.
Not all breather tubes address the issue of leakage and excess ink flow associated with high altitudes or air travel. The Parker patent 2,400,768 claims to address this issue. Breather tubes extending to the rear of the ink reservoir are prone to leakage caused by air pressure differential. The aft opening of these excessively long tubes is submerged in ink until the reservoir is almost empty – when carried nib up. The pressure differential associated with altitude changes causes the higher pressure in the reservoir to force ink out through the breather tube. Who knew patent applications could be interesting to read?
Contemporary Pens with Breather Tubes
Basically, any pen with a fixed squeeze filler, which is pretty uncommon, will use a breather tube, such as many of the Hero, the Bahadur, and the Dux models.
Chronicles of a Fountain Pen 
Interesting read. I’m going to look at one of my ‘bought a fair few months ago’ pens now. Not a high pressure issue as I don’t live on top of a mountain here in Wales! But I know I have a fixed filler on the cheap Smoothline pen I bought which leaked all the time. I got fed up with it and threw it in a draw. It was a beautiful writer. No nib leakage. Leaked within the pen barrel. I’ll revisit it and check it out……if I can find it! Cheers.
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The 1951 Parkette leaked over the weekend. My fault let it lie horizontally and a monsoon weather front rolled through. All kinds of pressure changes. When you live at 2100 m things can be interesting.
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Interesting stuff. Damage or small circumstantial changes due to how they are positioned for long periods! Who knows what pens go through in ebay (or equivalent) transit too. Packaging at times leaves a lot to be desired. I bought an acoustic dreadnought Eko 1970’s guitar that was wrapped in a bit of bubble wrap and a dustbin/trash can bag. Needless to say it had a huge crack to one of the joints. Vintage pens and nibs ought to be posted with consideration. Some of our alternative/cheaper postal service warehouses/delivery personnel, (not the Royal Mail), have been known to ‘Handle with (no) Care. Monsoons! All we get is rain and a few strong gales here in Wales. Result? Green as green nature wise. Cheers.
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What. I didn’t know this. At first I thought you were going to talk about the likes of the Sheaffer Snorkel. I thought it’d be practical at first, but upon further inspection, I think breather tubes would be a bad feature for workhorse pens. And I’m all about that practical usage. Anyway, thanks for this post!
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I know what a surprise – right. BTW the breather tubes in the Parker Vacumatic and 51 work great. Thanks for commenting
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