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Three problems:

  1. Internal friction due to stuffing materials. - Why does it not matter? If it does then there must be some limits like rpm etc.

  2. Not entirely leak proof. - Why are we supposed to keep it leaking (installation)

  3. Have o-rings eliminated stuffing boxs?

Edit: Stuffing box is a dynamic sealing mechanism --like o rings (static and dynamic sealing). They are used as seals in rotating, translating mechanisms.

To better understand here are 2 examples.

  1. Steam engines: if there was no stuffing box, all the steam would leak out of the piston rod side-- not creating pressure. In petrol/diesel engines, SB is replaced by piston rings. From SB in Steam Engine

enter image description here

  1. Boats: if there was no SB, water will start filling the boat from the hole -used for the propeller shaft. From Stuffing Box:

SB in Boat

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In Africa they use borehole pumps which are maintained with stuffing boxes. It is cheaper and easier to maintain than tight tolerance o-ring systems which require specialist imports. In countries like Zimbabwe the boreholes are very old and there are no imports available due to the nation's economics.

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  • $\begingroup$ i think it is also because they provide lubrication as well. maybe I am wrong since I've never seen one. $\endgroup$ – VIVEK SINGH Aug 30 at 13:10
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Yes they are still relevant. They are cheaper than mechanical seals, and the installed base is filled with them. No one likes the water drips, but it is what it is.

O-rings are not a solution.

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  • $\begingroup$ What are your thoughts on internal friction due to stuffing materials? $\endgroup$ – VIVEK SINGH Aug 30 at 7:30
  • $\begingroup$ @VIVEKSINGH friction is either an advantage (really handy for brakes on cars) or an inconvenience (so lubrication is required for bearings), either way it has to be designed for. $\endgroup$ – Solar Mike Aug 30 at 13:14
  • $\begingroup$ @VIVEKSINGH, clearly it's a disadvantage. I believe the constant water flow is as much for lubrication as to ensure the gland isn't tightened down too much. $\endgroup$ – Tiger Guy Aug 31 at 12:16
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It depends on the application... Your second picture is a typical stuffing box installation on a propeller shaft - probably on a sailboat.

One huge advantage of stuffing boxes on boats vs dripless shaft seals is that stuffing boxes usually don't fail catastrophically, they just start dripping more or leaking slowly. By contrast, a mechanical seal that fails will immediately start flooding the boat.

https://www.passagemaker.com/technical/dripless-shaft-seals

In other cases, the possible contamination due to the drips from a stuffing box could be a bigger concern (some pumping applications):

https://blog.chesterton.com/sealing/pump-sealing-options-packing-vs-mechanical-seals/

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