Which pump is quite?

[Dave]

Seems we are going way off topic on another thread, so I figured we should start this one.

There is alot of "standing off" going on as to which pump produces less noise, and I think everyone should first understand why pump noise varies, what is the cause, and how basic design comes into play.

First- pump noise often = bearing noise.
Bearing noise- is the result of bearing type and load.
Load- depends on balance and basic design which determines any preloading.

In a spinning motor, load is also dependant on magnetic interaction, which is effected by coils, stator, and magnets.

So, several things can effect the noise level of any pump when compared to another sample of same type, here is a quick list which is common to most pumps.

-Plastic resin grade and machine set up that day (effects balance and size)
-Bearing / shaft match
-Magnet grade and patterning
-Injection flash
-Rotor balancing.

What I suggest, instead of fighting which pump produces less noise, is an understanding that all pumps will vary in noise level.

This is why we describe the MAG is close to Ehiem 1048, as the Ehiem and MAG will vary. It is also why good reviewers make statements like "very quite" and do not sample direct noise, as you will need several pumps of same type for proper comparison

When someone stated X pump is quiter then his other Y pump, lets not argue as for him, it is likely so.

[Roscal]

A full magnetically suspended rotor is the best solution, no more bearings. Design is harder to achieve but a firm makes such designs, rotor could spin at high speed without any vibrations... no more balancing problems or worn bearings.

[Etacovda]

its quiet, btw

[Dave]

"A full magnetically suspended rotor is the best solution, no more bearings"

This is how a MAG should work, once started.
The bearings are only in place to help with start up noise, after that fluid dynamics takes over..... Well in most cases anyhow

The problem with "fully" magnetic suspension is pumping dynamics, you will need a close to zero turbulence flow, or uniform.....which leaves centrifugal out

With axial flow this maybe possible, as it has been produced with fans.

Of course magnetic material development may someday allow this in pumps as well.

More likely we will see the release of sapphire on sapphire bearings, then possible sapphire or ceramic mini in fluid ball bearings.
I think is both cases the factor them will be chamber design, as water noise will exceed bearing.

[bobkoure]

Originally Posted by Dave

There is alot of "standing off" going on ...

I think this might be a Canadian expression (?) Hoping it doesn't mean something like "offering to fight" as I was one of the folks commenting about comparative noise levels - and I was certainly not looking for a fight...

[Dave]

^ Not us, ok maybe I started it.... lets just stop it is all I am suggesting

[cotdt]

Are there ways to get existing quiet pumps to become more silent? I notice that undervolting does relatively little for noise.

How much of an improvement are the shappire-on-shappire bearings so far?

[bobkoure]

Originally Posted by cotdt

Are there ways to get existing quiet pumps to become more silent?

Yes.
Reduce vibration transmission (mount on foam or suspend, use soft silicone hoses - note that different foams will do a better/worse job depending on frequency, amplitude and axis of output)
Reduce sound transmission through air (install sound damping material in case or mount pump in sound damped case - note that damping must be 1/2 wavelength thick to be effective - go read up at SCPR or maybe search for my posts here as I'm sure I've "gone on" about that aspect)
Reduce sound re-radiation (add weight to sheet metal walls - there are "car audio" products (dynamat) for this. Some folks also contact-cement on rubber tiles or industrial carpet
(semi advanced) modify pump's vibrational output - firmly attach pump to a weighted base, then vibrationally isolate the pump/base unit. The idea is to drop the resonant frequency below the audio range. Note that pump loading (in the sense of "head" or resistance it's working against can also change vibration. If higher resistance nets you lower noise, you might want to go for a more restrictive block rather than just clamp the hose, of course...
(semi advanced) change pump axis to match foam's (or suspension's) best ability to damp vibration, route hoses for the same reason (in soft silicone, at least, a push-pull vibration is better transmitted than a side-to-side one) May not be possible/applicable

That's all I can think of - but I'm sure there are others...

[Cyprio]

The best noise isolator for my Aquastream was a kitchen pan scourer base - the yellow sponge and green scratchy top. It works like a dream.

[nikhsub1]

Originally Posted by Etacovda

its quiet, btw

LMAO, reading the opening post, I could not help but think the same thing. If you did not post this, I was going to.

[stev]

Originally Posted by Roscal

A full magnetically suspended rotor is the best solution, no more bearings. Design is harder to achieve but a firm makes such designs, rotor could spin at high speed without any vibrations... no more balancing problems or worn bearings.

Simple the DDC pump.

Know as the Danger Den DDC-12V or the Swiftech MCP350 12 VDC Pump.

See detailed and calibrated testing here ...
http://www.systemcooling.com/swiftech_mcp350-01.html

"... The rotor/impeller is the only moving part in the pump and since there is no rotating motor shaft there is no shaft seal to potentially leak. ... An electronically commutated 6-pole stator drives the pump rotor/impeller magnetically. ... In addition to producing a sinusoidal signal (instead of a square wave) to drive the stator coils, the controlling circuits also include a tachometer signal output and a variable speed input signal. "




• Nominal voltage: 12 VDC
• Operating voltage range: 6 to 13.2 VDC
• Nominal power (@ 12V): 8.3 W
• Nominal current (@ 12V): .69 A
• Nominal head (@ 12V): 13.05’ (5.7 PSI)
• Nominal flow (@ 12V): ~92 GPH (350 LPH)
• Connection size: 3/8” OD barb (10mm)
• Maximum working pressure: 22 PSI (1.5 Bar)
• Operating temperature range: Up to 140F (60C)
• Electrical connector: 4-pin Molex
• Weight: 7.3 oz (207 g)
• Noise (quiet room): 24~26 dBA @ 2’
• Motor type: Electronically commutated, brushless DC, spherical
• Pump MTBF*: 50,000 Hours

* Note: The 50,000 hr MTBF rating is based on Laing’s performance claims for their brushless DC motor with a lifetime in excess of 50,000 hours when operated at 12V. In addition, Laing has an extensive automated test program that measures total bearing wear on MCP350 pumps to further support their claims.

So, with the ceramic bearing, wear is not even noticable.

[stev]

Originally Posted by cotdt

Are there ways to get existing quiet pumps to become more silent? I notice that undervolting does relatively little for noise.

How much of an improvement are the shappire-on-shappire bearings so far?

He-he ...

3~4mm EPDM or Neoprene padding helps.

Also, the famous Maxwell Smart, "Dome of Slience" may work too!

[HammerSandwich]

Originally Posted by stev

Also, the famous Maxwell Smart, "Dome of Slience" may work too!

Cone! It was the Cone of Silence!

[bobo5195]

Originally Posted by stev

Simple the DDC pump.

Know as the Danger Den DDC-12V or the Swiftech MCP350 12 VDC Pump.

See detailed and calibrated testing here ...
http://www.systemcooling.com/swiftech_mcp350-01.html

"... The rotor/impeller is the only moving part in the pump and since there is no rotating motor shaft there is no shaft seal to potentially leak. ... An electronically commutated 6-pole stator drives the pump rotor/impeller magnetically. ... In addition to producing a sinusoidal signal (instead of a square wave) to drive the stator coils, the controlling circuits also include a tachometer signal output and a variable speed input signal. "




• Nominal voltage: 12 VDC
• Operating voltage range: 6 to 13.2 VDC
• Nominal power (@ 12V): 8.3 W
• Nominal current (@ 12V): .69 A
• Nominal head (@ 12V): 13.05’ (5.7 PSI)
• Nominal flow (@ 12V): ~92 GPH (350 LPH)
• Connection size: 3/8” OD barb (10mm)
• Maximum working pressure: 22 PSI (1.5 Bar)
• Operating temperature range: Up to 140F (60C)
• Electrical connector: 4-pin Molex
• Weight: 7.3 oz (207 g)
• Noise (quiet room): 24~26 dBA @ 2’
• Motor type: Electronically commutated, brushless DC, spherical
• Pump MTBF*: 50,000 Hours

* Note: The 50,000 hr MTBF rating is based on Laing’s performance claims for their brushless DC motor with a lifetime in excess of 50,000 hours when operated at 12V. In addition, Laing has an extensive automated test program that measures total bearing wear on MCP350 pumps to further support their claims.

So, with the ceramic bearing, wear is not even noticable.

Magnetic bearings have the problem that they dont damp small vibrations very well so tolerences have to be larger making things less efficent.

One way to improve noise would be to increase efficentcy of the pump. Im figuring noise is caused by areas of cavitation in the pump so a pump of higher efficantcy would be better. Companies dont bother making these as its not really worth it for water pumps.

I researched this for a related project some time ago, about the only thing that reduces noise without costing loads of money is two flow exits. Apparently this has a large effect on perceived noise. It loses you about 5% efficentcy (mostly head as opposed to flow rate) but it works.