Choosing rotating shaft seal for submerged water application
Choosing rotating shaft seal for submerged water application
(OP)
Hi,
I'm trying to specify seals for an application as follows:
- submerged, freshwater (river water; not many particulates; some chance of suspended sand)
- max pressure: 3 psi
- max vacuum: 8 psi
- shaft speed: 520 RPM, continuous, single-direction (non reversing)
- surface speed: 1.4 m/s (4.5 ft/s)
- shaft hardness: 25-27 Rc
- desired life: at least 2 years continuous operation
I'm having trouble figuring out what seal to choose; it seems a mechanical seal is overkill given the low pressure and speed. Packing is leaky and maintenance-heavy. I've heard O-rings "are not good in dynamic situations". And lip seals damage the shaft and wear very quickly.
What is a good suggestion for the main shaft seal?
By the way, the shaft bearings (ball) are on the "dry" sides of the shaft (think of the application as a shaft going through a box filled with water under the above pressure). Should I specify both shaft seals at the "box walls" as well as bearing isolators?
Thanks for your help.
P.S. I posted this in the "Mechanical Seal Engineering" forum a few days ago, but haven't received any replies. Sorry if I offended anyone by re-posting in this forum.
I'm trying to specify seals for an application as follows:
- submerged, freshwater (river water; not many particulates; some chance of suspended sand)
- max pressure: 3 psi
- max vacuum: 8 psi
- shaft speed: 520 RPM, continuous, single-direction (non reversing)
- surface speed: 1.4 m/s (4.5 ft/s)
- shaft hardness: 25-27 Rc
- desired life: at least 2 years continuous operation
I'm having trouble figuring out what seal to choose; it seems a mechanical seal is overkill given the low pressure and speed. Packing is leaky and maintenance-heavy. I've heard O-rings "are not good in dynamic situations". And lip seals damage the shaft and wear very quickly.
What is a good suggestion for the main shaft seal?
By the way, the shaft bearings (ball) are on the "dry" sides of the shaft (think of the application as a shaft going through a box filled with water under the above pressure). Should I specify both shaft seals at the "box walls" as well as bearing isolators?
Thanks for your help.
P.S. I posted this in the "Mechanical Seal Engineering" forum a few days ago, but haven't received any replies. Sorry if I offended anyone by re-posting in this forum.





RE: Choosing rotating shaft seal for submerged water application
Don
Kansas City
RE: Choosing rotating shaft seal for submerged water application
Since you have bi-directional pressure, you may need 2 seals at each sealing point.
By far your best resource for information on this will be seal manufacturers such as Parker or Bal Seal.
RE: Choosing rotating shaft seal for submerged water application
Best Regards,
Heckler
Sr. Mechanical Engineer
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