Two New Gludy Videos

[jfm]

unless I'm mistaken, the plate spinning on the teflon bearing is a little bit raised above the rest of the cover.
[/img]

All agreed 100% Mapis. Well, if (note, I say IF!) Speedseal are increasing impeller life by reducing the axial compression on the impeller that's a very poor show. The axial compression is a significant part of the fundamental seal design of the pump. Any user can reduce the axial compression just by inserting a thicker gasket. In some low-load/low-performance applications you might even get away with it, but customers ought to be told by Speedseal if the Speedseal Life axially lengthens the pump chamber in this way. Very poor form if Speedseal are doing this and not saying so imho. I very much hope they confirm that they are not doing this trick

 

[jfm]

I admit being pig ignorant on this, but if you reduce the friction on one face, its seems possible the impeller would last longer. Maybe the rear face does eventually cause the impeller to break up, but I guess a significant time improvement is an arguement for fitting them anyway, rear face frictionless or not?

Agreed gigm that removing friction on one of the faces is 50% of the job done. I'd consider fitting them for that reason alone, for carefull only-wet running

But they claim dry running miracles and it is hard to see, without furhter exlanation from them, why that is so. It is implausible that a dry run impeller mashes itself in 2.5mins, but if you remove the friction from just one face the other face will last 10x10mins. Something doesn't ring true. And then when we get explanations that the load has "migrated" to the low friction surface (which is simply nonsense) it looks fishier still. So it would be nice to get an explanation

 

[jfm]

I would have thought that part of the load on the inside face is borne at the hub and that may be an explanation for less friction between the blades and the inside face of the housing versus the outside face; there being no retaining structure at the hub on the outside.

The pump design ensures a designed compression load is borne by the vanes, not the hub. That's how it seals. It doesn't make any sense in pump design terms to have that load different on the inner versus the outer face of the impeller

 

[jfm]

Brendan
I 'dissed' the Water Bouy as you say on simple physics that prove the point.

Yup, as you pointed out the water buoy was measuring its buoyancy in mass of the object held afloat not newtons of buoyancy force, which is nonsensical. Funnily enough, they still do, so as a marketing tool maybe it works!

I am also wondering if I could video a real life dry run trial the next time I am back in the UK.

Yikes! A picture can indeed tell a 1000 words but i fear not in this case; watching a pump spin from the outside might be the dullest video imaginable. you'de definitley need some dancing girls to spice it up ;-)

You can be sure that the points made will be answered and not let to drop. I just want the horses mouth to respond if at all possible because they know far more about the trials and development than I do.

Thanks. Would be good to get an explanation, and a confirmation on whether they have lengthened the pump chamber (in the shaft axis direction I mean) or not

 

[PetiteFleur]

Hi Paul,
and welcome back

The speed seal looks good however I have never had issue with removing 6 screws instead of 4, the most consuming issue is removing the impeller itself, which I dont see the speed seal product helping either at sea or in a workshop.

Reference removing the impeller - I've modified a pair of cheap long nose pliers by heating the noses and bending then inwards so the easily grip the centre boss of the impeller - looking a bit like a pair of outside calipers. You'll have to experiment to suit your impeller. Use cheap pliers so when heated they bend easily - expensive pliers may not be quite so accommodating!
I keep them together with a spare impeller near the engine for instant use.
I've used the standard Speedseal in anger - I reckon it took about 30 seconds to change, and you don't lose those silly screws normally fitted.

 

[Nick_H]

Reference removing the impeller - I've modified a pair of cheap long nose pliers by heating the noses and bending then inwards so the easily grip the centre boss of the impeller - looking a bit like a pair of outside calipers. You'll have to experiment to suit your impeller. Use cheap pliers so when heated they bend easily - expensive pliers may not be quite so accommodating!.

... or invest £30 in an impeller puller, and keep the skin on your knuckles

 

[alexp]

Speedseal life development

Such a lot of interesting points about Speedseal - and an opportunity to go back to the inception of the development about 4 years ago.

Specialist pumps were produced with high slip bearings at both ends of the impeller because technical research showed that it was not the tips of the impellers passing over the cam which were the main source of friction and heat which burns out impellers, but the large surface area in contact with the end plates.

It was the overall increase in the efficiency of the total pump system which brought about the benefits.

Trials of the retrofit single end-version then showed a surprising 80/90% retention of those benefits because the effect on the critical characteristics involved in the pump is not a 50% one-ended influence.

The practical test results published by Yanmar (already discussed) and other manufacturers, go even further by showing the significant improvement in water flow characteristics, and the efficiency effect on the reduction in wear on drive shaft bearings.

These are independent practical tests to destruction. They do not involve speculation.

Please do let us have any further thoughts about Speedseal

 

[MapisM]

Hi alexp, and welcome to the madhouse.
I take it that you are the guy Gludy was talking about, and if so I wish also to thank you for exposing your views and reasons in a public forum, which is something very few builders (of anything, not just boating things) have the guts to do.
That said, I'm afraid you didn't actually answer the question which was raised. In fact, saying "because the effect on the critical characteristics involved in the pump is not a 50% one-ended influence" is like saying "because that's the way it is", if you see what I mean.
More specifically, does Speedseal reduce the axial compression on the impeller, or part of it?
That's what the video leads to think, and this is pretty much a legitimate question requiring a straightforward answer.

 

[Gludy]

Just to confirm that Alex is the owner of Speedseal and it is good to have him on the forum.

I think what he is saying is the practical test show you get 80 to 90% of the benefits but maybe the reason why that is the case. I agree has not been explained ... it would bne interesting to find out exactly why this is the case. I also think one gene maker has started fitting Speedseal as standard after their tests.

I accept that in practice you do get these benefits and as already stated I take the practical tests as a true reflection of what happens.

I would welcome Alex expanding further if at all possible.

 

[jfm]

Hi alexp, and welcome to the madhouse.
I take it that you are the guy Gludy was talking about, and if so I wish also to thank you for exposing your views and reasons in a public forum, which is something very few builders (of anything, not just boating things) have the guts to do.
That said, I'm afraid you didn't actually answer the question which was raised. In fact, saying "because the effect on the critical characteristics involved in the pump is not a 50% one-ended influence" is like saying "because that's the way it is", if you see what I mean.
More specifically, does Speedseal reduce the axial compression on the impeller, or part of it?
That's what the video leads to think, and this is pretty much a legitimate question requiring a straightforward answer.

Hi Alex and welcome to this forum, and thanks in particular for helping us out with our curiosity on speedseal

I share Mapis's views, that you've actually only repeated the claims and not explained them. Please could you explain why it's not a 50% each end thing, and please could you say specifically whether Speedseal maintains the same length of pump chamber or not (ie does it lengthen the pump chamber, so reducing the compression on the impeller in the axial direction?). Thanks

 

[alexp]

Thanks for the responses which help to focus on points outstanding.

As shown by all the practical tests, there is only a positive effect from the addition of the product. Theoretical discussion does not help.

The key factor is that pump chambers are not totally uniform and the efficiency improvements, the flow tests and the run-dry tests show that the effect of the cover bearing is more influential than a 50/50 result which might be expected.

 

[Gludy]

Whilst I accept the practical tests as true I wish i myself could understand it better.

The point about maintaining the same length as the the existing pump chamber still needs to be addressed.

 

[stuartw]

Having watched this thread with interest, I think I can explain why the outer face of the impellor is destroyed more quickly than the inside one.

Firstly, the inside face, is against what amounts to a lump of metal ie a casting, which has a significantly higher thermal mass than the outer face, which is composed of a thin metal plate. Thus the heat generated on the inside face, will be adsorbed by the casting and residual water in the pipe connectors plus a much bigger surface area, which of course will not allow the temperature rise to the point that the rubber will melt, and thus break down.

Conversely the outer plate being relatively thin, AND probably not in intimate thermal contact with the rest of the pump, will get very hot very quickly. If the outer plate was constructed more like a power supply heat sink, then the chances are the impellor would last a lot longer.

Secondly, I suspect that a thin “TEFLON” sheet , say 200 microns thick (with a few holes to allow water through) on both sides of the impellor and the metal, would work just as well. If this was combined with increasing the thermal mass of the outer plate, then this would provide an adequate solution.

Having said all that, I am slightly surprised that in this day & age, that a pressure sensor on the input ( or the output) of the pump, could not form part of a much earlier warning system, giving the helmsman the choice of shutting down, or reducing revs.

Stuart

 

[alexp]

There is no change to the length of the chamber and the small protrusion of the bearing disc is of a diameter which allows it to enter the recessed core of the impeller. Alex

 

[jfm]

Having watched this thread with interest, I think I can explain why the outer face of the impellor is destroyed more quickly than the inside one.

Firstly, the inside face, is against what amounts to a lump of metal ie a casting, which has a significantly higher thermal mass than the outer face, which is composed of a thin metal plate. Thus the heat generated on the inside face, will be adsorbed by the casting and residual water in the pipe connectors plus a much bigger surface area, which of course will not allow the temperature rise to the point that the rubber will melt, and thus break down.

Conversely the outer plate being relatively thin, AND probably not in intimate thermal contact with the rest of the pump, will get very hot very quickly. If the outer plate was constructed more like a power supply heat sink, then the chances are the impellor would last a lot longer.

Stuart, thanks, that seems a highly plausible explanation imho.

I'm amazed Alex refuses to explain or debate the science of WHY his product might work better, and just insists on his line "it works because it does". Sounds very evasive to me. Lucky for him he is not manufacturing anything more complex than a modified pump lid!

 

[stuartw]

Stuart, thanks, that seems a highly plausible explanation imho.

I'm amazed Alex refuses to explain or debate the science of WHY his product might work better, and just insists on his line "it works because it does". Sounds very evasive to me. Lucky for him he is not manufacturing anything more complex than a modified pump lid!

I did note from his last but one post, that he says "Theoretical discussion does not help"
from which I strongly suspect there has been no theoretical design, and all that has happened, is a first stab practical 'Solution' which appears to give improved results.

I think this forum may well have given him food for thought.

 

[Gludy]

I think the idea originally came from a system with a bearing at both ends which was then tried with a bearing at one end and worked. As long as it works I am happy and I do think it works.

 

[vertford]

Interesting stuff...

Nothing really to add but I came across this thread while writing up my notes/crib sheet/flow chart from my Diesel course. They mentioned the Speed Seal system, which I didn't realise came in bespoke sizes. (Thought they were all circular)

I think I have learnt more about impellers, their make up, covers and assorted products in last 20mins then is really necessary on a Bank Holiday!!

Will get to know 1GM10 intimately...

 

[MapisM]

Having said all that, I am slightly surprised that in this day & age, that a pressure sensor on the input ( or the output) of the pump, could not form part of a much earlier warning system, giving the helmsman the choice of shutting down, or reducing revs.

Yep, having one of the very few boats which comes standard with a raw water circuit pressure gauge, I also find it extremely useful.
She doesn't have any alarm though, just the gauge. Probably the reason is that an alarm would require a rather sophisticated setup, 'cause it's normal for the pressure to vary between 3-4 PSI at idle and 25-27 PSI at 5200 RPM.

Interesting theory re. the differences between the inner part of the pump and its cover, you might well be right. In which case, you've given Alex some food for thought and possibly a hint for updating also his own website, whose "Technical details" page is not impressive to say the least.
Not to mention the very unprofessional "Test reports" published by various magazines, though I guess that magazines these days don't really care, as long as the advertiser pays to get his page published...! Out of 5 magazines, only one actually pretends to have installed the thing in one of their test boats, and aside from confirming that the installation was "easy and fairly fast", it just says that they'll check the impeller wear and "keep you posted", go figure!

Anyway, I am actually happy if the thing works as claimed.
Having challenged Alex and his product a bit doesn't mean I'm not appreciating the results, if they are anywhere near the claims.
I would even make him a proposal. Since as I said my boat already has a rather accurate water pressure gauge, I am willing to buy a speedseal and give it a proper try, testing one of its claims: the "performance increase".
What I can provide FOC are two sets of pressure/RPM curves, "stock" and "speedseal".
If the speedseal curve shows any kind of pressure increase throughout the RPM range, I'm pretty sure that literally thousands of users of the same engine will RUSH to buy the thing, because:
a) cooling is very critical for these engines/headers;
b) the pump is located in an awful position, whose access in most performance boats is a nightmare;
c) these boats are mostly stored dry, which means that at any given engine startup the impeller runs almost dry for a while.

Actually, I'd be a happy bunny even if the speedseal curve shows no improvement, as long as it doesn't fall below the stock curve - in which case I think it would be fair to ask my money back.
The engine I'm talking about is the Mercruiser 496HO.
And if the thing works, I've got a couple of Cat mains and an Onan genset already waiting in the queue, no kidding.

 

[Gludy]

I think that test would be very interesting and worthwhile Alex doing.