×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

pump packing

pump packing

pump packing

(OP)
I have a vertical peerless turbine pump ,it was supplied with rope packing cut on a 45 degree angle packing container is greased with grease zerk .is this proper?

RE: pump packing

For services where a small amount of leakage is acceptable, this is common.  The packing will leak a small amount continuously, even if it is well greased.  If the leakage is unacceptable, it could be converted to a mechanical seal.  However, depending on the particular pump design, there is often inadequate shaft seperation to allow the seal to be replaced without removing the motor driver.  We have installed split mechanical seals in some similar installations.  A split seal may leak a few drops per minuted, but it should leak much less than packing.  In addition the seal will consume less power and will not result in wear to the shaft like packing.

RE: pump packing

We have substituted what we call "Teflon Rope" packing for the standard packing.  We got it at WW Grainger.  Stuff is pure teflon and looks like teflon tape wound into a rope configuration.  Works much better than standard rope, allows you to tighten the packing down a little more with less heating, lasts longer without frequent adjustment.

JJPellin is correct though.  If you can go to a mechanical seal successfully you are better off.

PUMPDESIGNER

RE: pump packing

One company i represent has developed an aftermarket ' zero maintenance stuffing box" to replace the standard packing / shaft arrangement.  It incorporates a separate sleeve that slips over the drive shaft, on which packing seals.  The advantage is the sleeve is made to resist wear, and when eventually it needs replacement, the shaft does not require replacement, which involves lifting the pump.  
This arrangement is beneficial where the water being pumped has particulates, such as in spring run-off.  We also installed one where the shaft had been badly scored by over enthusiastic packing tightening, and the customer preferred to not lift the pump (difficult access for crane etc)
I believe that Peerless markets a similar arrangement as an option.

RE: pump packing

The seal system you have is usually more than adequate for most aplications unless a small amount of leakage is a problem. For a "packed gland" as you have, the correct packing selection is important and you should request detail from a reliable source together with detail on proper maintenance proceedure.

RE: pump packing

Fred9,
    This type of packing configuration is very common in vertical turbine pump units. A few years ago I stumbled on a type of Graphite Packing that works exceptionally well. It is called Palmetto Pinnacle Packing made by Tweed & Co. 25 Engerman Ave Denton, MD. Phone-410-479-2244. This packing is the only packing I have on the shelf in our repair facility. Because it is made of 100% graphite it is a pure lubricant and will not burn when tightened to zero leakoff. It also has the lowest drag co-efficient of all the packings I have researched. Used in conjunction with ceramic coating at wear areas of sleeves and shafts,I have had pumps with over 4years use with zero or no wear at the packing area. Ceramic coating should be applied by a reputable vendor to an RMS finish not to exceed 15.
    The only draw back with this packing is that it is soft. In systems with high concentrations of suspended solids, metal in particular, the abrasiveness tends to tear the packing apart. Unless a clean flush at the lantern ring placed in the bottom of the packing gland us used. This configuration will keep a clean water barrier between product and packing.
    The Teflon rope packing Pumpdesigner mentions is fairly good, but. Teflon will burn if not lubricated properly or tightened too much. Once teflon burns it forms a hard abrasive crust at the point of burning. This will increase wear at either the sleeve area or shaft.
    If a split mechanical seal is decided on insure you install a steady bearing on the shaft if your motor is of the hollow shaft design. If not, the vibration of the shafting between the coupling hub at the top of the motor and the mechanical seal will shorten the life of the mechanical seal. These steady bearings can be gotten from the motor manufacturer.

Poppeye

RE: pump packing

Poppeye,

I'm impressed and very well said.  I agree with you 100% packing has always been a nitemare but compared to mechanical seals the cost savings is tremendous.

Split seals are OK but have speed restrictions and when the pump is being overhauled don't install the split faces buy the one-piece seals.  Later should you have a failure of the mechanical seal (only) you can split the solid face seals and install the two-piece split ones.  Solid faces are always better than split no matter what anyone tells you.  

All you guys did a good job on this packing issue its one of my favorites I fight with in the field all the time.

wlovison@toyopumps.com

RE: pump packing

Mechanical seals are good for pumps designed for them. Be careful if you wish to change from packing to sealed pump, though. Some of the old designs effectively use the packing as a sort of auxiliary bearing. An ill thought out change from packing to mech seal can lead to other forms of mechanical unreliability.
 Also, bear in mind with vertical pumps, you can get a gas pocket under a seal which results in the faces running dry. This can lead you to needing an external lubrication or tandem seal.
 There are traps for the unwary, and seal vendors sometimes don't have the full picture.

RE: pump packing

Fred9
   Like Tonyh said in vertical turbine mechanical seal installations there can be an air or gas pocket under the seal chamber. Although this pocket normally will not last for long after start-up, just a couple minutes of run time can damage the seal faces from heat stress. Most single cartridge seals have a vent or flush port incorporated to provided seal flush or cooling at the seal faces. Normally the flow into this flush port is from clean product discharge into the flush port and then it enters the pump through the mechanical seal and the gland housing. On vertical turbine pumps the flow can sucesfully be piped to have trapped air or gas in the pump head to be vented through the seal with a small pipe or tube attached to the vent/flush port of the seal then have that discharge into the fluid sump through holes either drilled in the pumps base or on most units there are plugged holes for packing leakoff to be directed through the base from the gland housing. Or a separate seal flush can be piped into the vent/flush port, keeping in mind the seal flush pressure will have to be higher than the discharge pressure of the unit. This will ensure proper flow across the seal faces. Also keep in mind where the pump is located in relation to outside temperatures. Should the pump be exposed to freezing temps, this vent line can and will become blocked with ice thus making it useless. In this case, heat tracing is a must.

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources