Airflow Restriction in Tobacco Smoking Pipe

[Mookie27]

Hi everyone! Forgive me if this is posted in the wrong part of the forum and thanks in advance for any insight here.

I'm a pipe smoker and I just received a very nice artisan pipe that has an issue that is completely unique in my experience (and that of the pipemaker). Basically, when drawing air through the pipe the airflow starts out smooth and open but very quickly starts to feel restricted, almost as if something were caught in the airway. It's doing this without anything being packed in the bowl and it happens every single time when pulling on the pipe directly straight.

If I manipulate the way the air is being pulled through the pipe by changing the angle that the pipe is facing my mouth, the draw seems to open back up. I have double checked that the airway is clear by shining a light into the bowl and there is nothing obstructing it. It feels almost as if there is a sort of suction being created somehow when air is pulled directly through the pipe but my understanding of physics is too elementary (read nonexistent) to know why that might be happening or even if that is what's happening.

The pipemaker is similarly perplexed so I figured I'd reach out to a group much more well versed in physics than myself. It's a long shanked Lovat style pipe and the airway is drilled at 4 mm. My suspicion is that the dimensions of the pipe happen to be in a sort of "sweet spot" that is creating the issue. Does anyone know what might be going on? If so, anything that might be a simple fix? Thanks for any help!

 

[Bystander]

Sounds more like manufacturing residue, take a pipe-cleaner to it. It might also be polycythemia, nature's own cure for smoking.

 

[Mookie27]

Ignoring the unnecessary snarky comment, the airway is bare briar--there is no "manufacturing residue" or stain of any kind and the airway is totally clear.

 

[dlgoff]

As @Bystander says. Use a pipe cleaner.

 

[Bystander]

the airway is bare briar-

Not charred/seasoned? Pre-stroke pipes were billiards, bulldogs, and one bulldog meerschaum (never did get it "ripened"/colored); memory is they all, excepting the meerschaum, were blackened/seasoned/charred when I bought them new in Lawrence, KS. They all had to be further "broken in," condensers thrown away, before they could handle full bowls without plugging on crumbs.

New pipe, no tobacco, won't draw? There's loose briar chips/stem material somewhere.

 

[dlgoff]

... when I bought them new in Lawrence, KS.

Lawrence is the town I use to live in. Which shop did you buy them in?

 

[Bystander]

Which shop did you buy them in?

Main St., SW corner, couple blocks south of the bridge, got it on the tip of my tongue ....

 

[dlgoff]

Main St., SW corner, couple blocks south of the bridge, got it on the tip of my tongue ....

Main St or Massachusetts St? Smokers Depot maybe?

 

[Bystander]

Massachusetts St?

"Doh."

 

[Mookie27]

Not charred/seasoned? Pre-stroke pipes were billiards, bulldogs, and one bulldog meerschaum (never did get it "ripened"/colored); memory is they all, excepting the meerschaum, were blackened/seasoned/charred when I bought them new in Lawrence, KS. They all had to be further "broken in," condensers thrown away, before they could handle full bowls without plugging on crumbs.

New pipe, no tobacco, won't draw? There's loose briar chips/stem material somewhere.

It's not that the pipe won't draw, it's that the draw feels slighty restricted when drawing on it from straight down the pipe. If I draw on it at a slight angle in any direction it does not feel restricted at all and that's why I'm wondering if there is something about the dimensions that are creating a sort of vacuum or something when air is drawn straight through it.

This is indeed bare wood. While many pipes do come with a bowl coating there are also many (usually from higher end artisans) that come with no coating at all. Some people prefer one or the other but pipes definitely come both ways. Same thing with condensers/stingers. In fact, the vast majority of tobacco pipes don't have these things. The big one that does is Kaywoodie and there are a few others but they're the exception to the rule.

As @Bystander says. Use a pipe cleaner.

Have used a pipe cleaner but I can also look straight down it with a light shining through the bowl and see the entire airway through to the bowl. There is nothing in the airway or bowl except for smooth, bare wood all the way down.

Here's a photo showing the lack of coating on the bare wood that goes all the way down the pipe.

 

[dlgoff]

It's not that the pipe won't draw, it's that the draw feels slighty restricted when drawing on it from straight down the pipe. If I draw on it at a slight angle in any direction it does not feel restricted at all and that's why I'm wondering if there is something about the dimensions that are creating a sort of vacuum or something when air is drawn straight through it.

This is indeed bare wood. While many pipes do come with a bowl coating there are also many (usually from higher end artisans) that come with no coating at all. Some people prefer one or the other but pipes definitely come both ways. Same thing with condensers/stingers. In fact, the vast majority of tobacco pipes don't have these things. The big one that does is Kaywoodie and there are a few others but they're the exception to the rule.Have used a pipe cleaner but I can also look straight down it with a light shining through the bowl and see the entire airway through to the bowl. There is nothing in the airway or bowl except for smooth, bare wood all the way down.

Here's a photo showing the lack of coating on the bare wood that goes all the way down the pipe.

View attachment 338394

That's a mystery to me.

 

[Baluncore]

Drilled wood will have many bare fibres at the surface. I expect that will cause a restriction when the pipe switches to turbulent flow. At some critical flow rate, the pipe will gag like you describe.

To eliminate the irregular fibre surface, push a close-fitting red-hot wire along the bore. That will char the surface fibres, allowing a laminar flow to be maintained at higher flow rates. It will also reduce the ability of particles to be caught in the bore.

 

[sophiecentaur]

Don't try this at home, folks.

(It had to be said as the risk to life is a lot more significant than some of the activities that PF doesn;t like being discussed.)

 

[berkeman]

Ignoring the unnecessary snarky comment

So you're new here, right? ...

Anyway, have you tried your experiment on each half of the pipe individually?

https://pipesmagazine.com/forums/threads/taking-apart-a-kaywoodie.27274/

 

[jack action]

I quote Messrs. Matlick and Ivarsson from this article: “Unrestricted airflow through the entire channel is essential for an easy-smoking pipe ... ’Once you pick the shape and size of pipe you like, test the airflow,’ says Lars Ivarsson. ‘Draw in through the empty pipe at normal smoking force. There should be no sound or, at most, a deep, hollow sound. This means the airflow is not restricted, an essential element of a good-smoking pipe. If you have any whistling sounds, ... meaning restricted airflow, you will probably have trouble keeping it lit and it will probably smoke wet. According to Lars, ‘You’re getting turbulence in the airstream when you exceed a certain speed. The sound of that turbulence indicates that the smoke will get separated. Smoke is actually microdrops of moisture containing hot air and aroma. When air passes quickly through a restricted passageway, turbulence moves the heavy particles, including the moisture, to the perimeter, like separating cream from milk. This can be caused by too small a diameter or sharp corners in the smoke passage [which is] an extremely important issue ... [T]he physics of the boring of your pipe will definitely have an impact on the taste of the pipe and your smoking pleasure. For all of his pipes, Lars uses a four millimeter [3] channel from one end of the pipe to the other. This may vary with the pipe maker, but the sound test will still hold true.”

I know you said you already have a 4 mm channel but you should check for sharp corners and eliminate them. Setting a chamfer - a fillet is even better - at any inlet or outlet will also help reduce turbulences.

Also, check for misaligned channels between pieces. In the image below, the inside bore at 4 should be perfectly aligned with the inside bore at 6.

 

[emac-917]

Basically, when drawing air through the pipe the airflow starts out smooth and open but very quickly starts to feel restricted, almost as if something were caught in the airway. It's doing this without anything being packed in the bowl and it happens every single time when pulling on the pipe directly straight.

What an interesting problem. On pipesmokersden, I came across a hypothesis about the effect of a flat-faced tenon on laminar flow within the draft hole. The gentleman (Sasquatch) proposed beveling/funneling the end of the tenon to reduce turbulence.

It seems logically sound though I don’t have any personal experience with this type of modification.

Original post on pipesmokersden:
https://pipesmokersdens.com/threads/savinelli-autograph.6369/page-2#post-274556

 

[Rive]

drawing air through the pipe the airflow starts out smooth and open but very quickly starts to feel restricted

By any chance, is there any whistle- or flute- like sound/vibration/noise appearing when the 'restriction' starts?
Could you please check it with a microphone (connected to a PC, which running some sound analysing SW)?

 

[emac-917]

Setting a chamfer - a fillet is even better - at any inlet or outlet will also help reduce turbulences.

I just learned about chamfering the tenon in this context. Setting a fillet sounds interesting. Would you say a convex or concave fillet would work best?

 

[jack action]

I just learned about chamfering the tenon in this context. Setting a fillet sounds interesting. Would you say a convex or concave fillet would work best?

Compared to this:

A chamfer like this:

represents 50% less losses.

A fillet like this:

represents at:

• $^r /_D = 0.02:\ \$ 44% less losses;
• $^r /_D = 0.04:\ \$ 52% less losses;
• $^r /_D = 0.06:\ \$ 70% less losses;
• $^r /_D = 0.10:\ \$ 82% less losses;
• $^r /_D = 0.15+:$ 92% less losses.

(source)