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# Slurry pump seals

## Slurry pump seals

(OP)
All:

My experience with slurry pumps is zero…  I’m getting ready to search the net for crash course info.  If anyone knows some good links I would appreciate it.

The current problem:

Within the next several days or weeks I have to review some slurry pumps that are operating in series due to the head required.  As I currently understand it the problem that has been experienced with the pumps so far is the seals or packing not lasting.  At this time I don’t have much information and will probably repost in the next couple weeks.  Any ideas of what to look for or possible solutions to consider while I’m collecting data would help.

The slurry pump manufacture will be at this meeting, so it is going to be a team sport…  I just want a little insight before we get there.

Thanks!

### RE: Slurry pump seals

Sounds as tho you are going to Fort McMurray ! Take your thermal underwear.  Seriously, I supply aftermarket sleeves into this and other mining markets with series pumping applications with those problems. One item is gland water quality and supply. Item 2 is  when there are pressure spikes in the delivery line which cause back up into the stuffing boxes.  The pressure requirement for the later stages puts a real load on the packing / sleeve arrangement and it had better be done right and broken in correctly or they will not last.  Feel free to call Mac 403 278 7604.

### RE: Slurry pump seals

d23,

I agree with macmil.  Whether this is at Syncrude, Suncor or any other mining operation the same problem exists.  Sealing an abrasive liquid is extremely difficult.  The key solution is to provide sufficient clean water flush to keep the packing (or seal faces)cool and clean.  In other words, if you can provide a flush at pressures above the pump stuffing box pressure (and in excess of the spikes indicated by macmil), you will overcome most of the problem.  In effect, what is required is to actually have some flow of the flushing liquid into the pump housing.

The sealing problem is multiplied by the pumps installed in series and the resultant high differential pressure across the stuffing box.

mac

### RE: Slurry pump seals

Kawartha et al
In my previous post re COS I should have included that the opinion expressed was purely personal, and that there is no intention to recommend the purchase or sale of any security. I am not registered or licensed to offer investment advice, and anyone considering any investments should perform their own due diligence.
mac

### RE: Slurry pump seals

Thanks macmil. Are you a lawyer???

I own some too.

Regards

### RE: Slurry pump seals

D23:

Okay- I wrote the following last week, but now that I’ve come back and read that you’re supplying the water support system for the plan 32…  well- that follows the parenthesis.

(I’ll give you the lowdown about shaft sealing.  First, choose a pump with a large bore stuffing box.  This will make it so much easier to get a seal to work.  More room for components, more area for cooling…
I know that several makers of ANSI sized pumps make a vortex generator that is part of the cast of the back-plate that really helps with slurries.  Goulds calls it VPI and Flowserve- Durco calls it FML, I think.
If the OEM you like does not there are aftermarket vortex generators that can be installed, Sealmate comes to mind.

Slurry seals get a bad rap.  They do.  It can be done.  If the solids concentration is about 10% or so look into the plain old elastomer bellows pusher seals with hard face materials, ex, John Crane Type 1, Flowserve Pac Seal…  These work famously, a single spring won’t clog easily, the elastomer bellows holds up well in slurries too.  If the solids content is higher there are two other types to look into, metal bellows seals, or the seals touted as slurry seals.

Metal bellows seals work well because the edges of the bellows “knife” through the solids, and windage is created around the bellows helping to increase flow around the seal as the bellows rotates.  Metal bellows seals also have the advantage of a stationary secondary seal element.  The o-ring doesn’t have to move, so no O-ring hang-up.

The seals promoted as slurry seals are generally made to work with the special stuffing boxes listed above.  These designs generally use a stationary O-ring to wipe against the seal face to exclude solids from the springs that move this same seal face.  The seals are made with a profile that tries to create a smooth flat profile around the faces to minimize the turbulence around the faces and reduce the chances that they’ll be abraded.  This is partly why they are designed to work without a flush.

A Plan 32 Flush with a throat bushing is the easiest way to make a seal work in a slurry service.  The flush rate is adjusted to cool the faces with clean fluid and to create enough pressure and flow through the stuffing box and the bushing to exclude the abrasives.  Heck, the bushing is a plus if your bearings ever go to pot.  Hard faces are a must; the solids can be crushed and spat out the atmospheric side.  If you are really concerned, a Plan 62, or quench can be used to both cool the seal faces from the atmospheric side, and flush solids away from the faces.

If the solids are heavy enough and you want to try, a Plan 31 is the use of a cyclone separator off the discharge, with the clean fluid to the stuffing box, and the dirty fluid back to suction.  These can be tricky, because they have to be “tuned”, the losses through the tubing have to be considered for these to work best.  Cyclones can also plug and be a real pain in the keester.

I’ve just had really good experience with a double metal bellows seal in service at a Calcium Chloride unit.  A Galagher pump with a stuffing box that used to be packed with aramid packing, a lantern ring, and what the other vendor called an excluder packing ring (just a solid teflon packing ring cut on a bias so it closes in on itself as you tighten the packing gland- a bushing).  The pump pulls the “mud” from the bottom of a clarifier and sends it to a filter press.  We installed this back to back metal bellows seal with a modified plan 52, or a 54, plant water piped in to the area between the seals at 20 or so pounds above the stuffing box pressure and back out to the sewer.  This thing has run like a champ.)

Now for the rest-

What is the current configuration?  If the water is clean I suppose the problem is keeping it at a constant pressure or at the pressure required to exclude the slurry from the stuffing box.  Consider some kind of accumulator or N2 bottle system to boost the pressure with a regulator.  I know that at least one company offers what looks like a reservoir, but has a disc and rod so that on one side of the disc the reservoir is at the discharge pressure, and the other side, due to the difference in area of the disc because of the rod (Pressure= Force/Area), is at some constant ratio higher. (check this link out- http://www.colossusgroup.com/products/zyg_english.htm )

If the pressure isn’t the issue, what is?

Josh

p.s.-  Just remember that the Venezuelans are having their own problems with strikes and politics too.  And even if they do get past those issues and boost production, Venezuelan crude is higher in Sulfur.  More of that means more maintenance, more down time, and decreased profit margins.

### RE: Slurry pump seals

(OP)
longeron, all:

Thank you for all the info.  I actually printed this post for future reference.

The slurry problem was identified and repaired before I got there.  That was good too, because I didn't have to look like an idiot!!!

FYI

I knew the seal water pump was not the problem; I designed it!

Thanks again!

### RE: Slurry pump seals

Don't leave us hanging, what was the issue?

### RE: Slurry pump seals

(OP)
longeron

This was a people thing.  The slurry pump problem was identified and corrected before I got to the site.  We had several other problems to deal with so this didn't bother me.

One of the engineers in my office has a bumper sticker on his car:

You just can't fix STUPID

I am still quite impressed with your post!  Information plus...

Thanks

### RE: Slurry pump seals

The reason for seal or the packing not lasting could be a fault in the shaft alignment.Hence it would be worthwhile checking the alignment of the shaft and the load distribution on it.

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