High-Banking Simply Stated

Mechanical Water Pump Seals

About the greatest problem you will encounter in wet water prospecting is Mechanical Seal failure on your water pump. This will happen not if but when! How you will pick if your seal is a shot duct your pump may start sucking air and you will get a very noticeable performance drop. And or a water leak along the main drive shaft. Below will give you an idea just what a Mechanical Seal is and what they do.

Mechanical Seals for Water and Wastewater Pumps

By Allan R. Budris

Because mechanical shaft seal failures are the number one cause of pump downtime, the writer decided to dedicate this column to mechanical seal basics.

Years ago, most pump shafts were sealed using rings of soft packing, compressed by a packing gland, but this type of shaft seal required a fair amount of leakage just to lubricate the packing and keep it cool. Then came the development of the mechanical seal, which accomplishes the job of restraining product leakage around the pump shaft with two very flat surfaces (one stationary and one rotating). Even though these mechanical seal faces also require some (very small) leakage across the faces, to form a hydrodynamic film, this leakage normally evaporates and is not noticeable. Most pump shafts today are sealed by means of mechanical seals. However, because of the delicate components used for this new sealing method, mechanical seal failures are the greatest cause of pump down time. This begs for a better understanding of this seal type and its application.

Main elements of a mechanical seals

All mechanical seals are constructed with the following basic sets of parts: A set of (very flat) machined and lapped primary sealing faces: The very close (near) contact between these two flat mating surfaces, which are perpendicular to the shaft, minimizes leakage. Dissimilar materials are usually used for the faces, one hard and one softer, in order to prevent adhesion of the two faces. One of the faces is usually a non-galling material such as carbon-graphite. The other surface is usually a relatively hard material like silicon-carbide, or ceramic. However, when handling abrasive, two hard surfaces are normally used:
One face is held stationary in a housing
The other face is fixed to, and rotates with the shaft.
A set of secondary static seals, typically O-rings, wedges and/or V-rings.
One static seal, seals stationary component(s) to the housing
The other seal, seals the rotating component(s) to the shaft (it normally moves axially on the shaft or shaft sleeve)
A spring member to maintain face contact, such as a single spring, multiple springs or metal bellows.
Other mechanical seal hardware, which includes shaft sleeves, gland rings, collars, compression rings, and/or pins.

Mechanical seals require clean water, or other compatible liquid, for the lubrication of the seal faces. The faces in a typical mechanical seal are lubricated with a boundary layer of gas or liquid between the faces. Lubrication can be provided from the pumped liquid itself or from an external source, depending on system requirements.

http://www.waterworld.com/articles/...cal-seals-for-water-and-wastewater-pumps.html

replacement of the mechanical seal on the water pump

https://youtu.be/_baA-Nj22iU

[video=480,360]https://youtu.be/_baA-Nj22iU[/video]

https://youtu.be/Ntu1K-22gFo

[video=480,360]https://youtu.be/Ntu1K-22gFo[/video]

Jemba great videos on pump maintenance, one other thing to use if you don't have a soft hammer is use a brass drift but it has to be brass so you don't damage the impellor.
I rechecked the water rate on my 2" hidels pump & it is actually 8000gph- used 5 ltrs per gal not 4.5 for imp gals.

That is a very good tip thanks mate. cheers Jemba

Lot of judgement here but heat the impeller quickly until water or spit just fizzles off then crack them undone.
Reasons are first, If the impeller is heated quickly, Not much heat is transferred to the shaft hence it expands
just that little bit.
If you use too much heat, You will stuff the seal on your motor or melt the impeller if it is aluminum.
.
Final big point is, The threads for the impeller and or shaft are usually left hand. Not right hand.

Thanks mate never knew that. cheers Jemba

Good tip on heat but heat should only ever be a last resort, another old trick is to get a drift & hit directly on the nut you can see in the middle of the impellor most times this will loosen up bolts & such enough to undo them.

AtomRat said:

Ok..ive got a question while where sort of on pumps. Sometimes ive seen at the inlet the water supply can tend to swirl and make a vortex down to the inlet. Even if its well under the water and deep. Is this eddy currents causing it say if were in a creek?

If the water IS low and you have this problem, whats the best solution? Im guessing a guard over the top side of the mesh?

Click to expand...

You can use a flat disc about 600mm diameter (not important to have it round either) placed over the top of the foot valve. That will not allow the vortex to form. This is used when pumping out buildings after flooding. Depending on the pump it may allow pumping for another 300mmm or more. CFA use these as well. Couldnt quickly find any reference to them on the internet. Ken.

Good tip thanks mate.

Great info for us newbies mate. List is precise and to the point.Love the info on the shovels especially.

Thanks mate the P.A site is about one of the best for information and research into what is what and what should do what. and it dose save you big bucks.

Hi every one.
Does any one now of where I can get same info on the Regulations regarding the use of High bankers and small pumping system in NSW.
As I'm in the process of building one to fit over a sluice at I made a couple of year back.
I dont want to waste my time building it if its to over regulated like every thing is.

Rod Smith

Rod, you arnt known as" fossil" are you?

Rod you may find what your seeking in this section. https://www.prospectingaustralia.com/forum/viewforum.php?id=67 cheers Jemba

Thanks for the report, I am currently building a WalBanker - this is some really sensible advice herein, thank you

Some impellers are plastic so heat method is out. I use a chain wrench wrap cardboard or rubber strip around the impeller and presto. Also a good squirt of wd for a 24 hour soak helps.

Shit just watched the video exactly what he done

Hey guys just about finished the highly banker. That I've been constructing. Now I'm looking at pumps hi volume. Not so much hi pressure just transfer I'm thinking. 1.5" ezy to lug around. But the 2" units you have it all. But the weight dragging it around in the scrub? so I'm back to the 1.5". Any ideas makes models and so on.
The spec of the sluice.
Is 300w x 75d x 1200L X 2.5mm
Wash box 300w x 450L X 250H with grizzly bars and mats, ripples, screens for pending conditions and so on. And a box of stuff as well. From old sluices.

Jackass said:

Hey guys just about finished the highly banker. That I've been constructing. Now I'm looking at pumps hi volume. Not so much hi pressure just transfer I'm thinking. 1.5" ezy to lug around. But the 2" units you have it all. But the weight dragging it around in the scrub? so I'm back to the 1.5". Any ideas makes models and so on.
The spec of the sluice.
Is 300w x 75d x 1200L X 2.5mm
Wash box 300w x 450L X 250H with grizzly bars and mats, ripples, screens for pending conditions and so on. And a box of stuff as well. From old sluices.

Click to expand...

If you can afford a Honda WX15 they are only 9kg and pump around 240 litres/min at zero head ( $740)

That is more suitable for a 250 wide sluice but may also run 300 wide depending on the type of mat or riffles you use and slope in the sluice.

What type of mat or riffles are you running ?

If it's gold hog mats I would say you need a bigger pump than 240 litres with that width , I like to have absolute minimum of 1/2 inch water over my mats and riffles , preferably more like 1 - 1.25 inches but I do shovel hard and fast compared to what most do.

100 % agree with headsup, the wx15 is a great little unit remember the smaller you go the more noise or more hose you'll need.

I do agree with the above the Honda pump is indeed one of the best for what we do. As a cheap alternative the Rato pump, Genquip pump or the Thornado pump are as good as the Honda Wx.
Now here is the bit you need to know After about 5 years or so, on your Honda you can expect your Mechanical Seal to let go, I know of 3 Hondas that have had this trouble and the seal needed replacing at around $170 for the replacement in a shop or around $80 if you do it yourself. . Back in July this year I had to replaced the Mechanical Seal in my Honda wx at that time the corrosion was cleaned form the pump. The pump had always been stored dry with no water in it. Now it was the time to give the inside a lick of paint. What I had to do was clean the corrosion off then give it a good spray with wd40, this I let site for 24 hours before the next step. Clean Prime and paint. By doing this it will not stop the corrosion but it will slow it down. Now for $800 for the Honda and around $200 for the others you could get 3 to 1 for your money. The corrosion takes a big part in killing the pump seal. Something to think about.