Rotary Pump HX Espresso Machines & Their Sounds

[dmankin]

I own a Bunn ES-1A. Having upgraded from a vibe pump machine, I always thought that the lack of all-out buzzing was a great thing. I recently, however, stood next to a Nouva Simonelli Mac Digit as a few shots were pulled. It was FAR quieter than my Bunn - nearly silent. Now focussed on the sound a pro machine makes, I visited a brand new (hence nearly empty & quiet) coffee shop in my area. When the barista switched on the pump, I heard nothing. I also have a friend who I visited this evening, and his machine (also HX / rotary pump) makes about the same intensity of a whirring sound as the pump on my Bunn.

My question is this; Should a properly functioning rotary pump be silent, near silent, or make a whirring sound? My pump is soon to be rebuilt anyway, but I am very curious to know if a noisy rotary pump is necessarily a pump in need of a repair/rebuild, or is it's OK for one to be noisy.

Thanks!

David

[HB]

My question is this; Should a properly functioning rotary pump be silent, near silent, or make a whirring sound?

Vibratory pumps get a bad rap because... they vibrate. If you run one free from an espresso machine's casing, it makes less noise than an electric razor. Alas vibratory pumps do indeed vibrate, producing a tinny reverberation of interior components. I'm not making this up, I "outboarded" mine and the noise level is about the same as an inboard rotary pump:



Rotary pumps by their nature produce very little vibration. If they have an ample water supply to avoid cavitating, they operate nearly silently. If they're mounted externally as is the case in the majority of cafes, you will hear nothing unless you open the cabinet and listen carefully. Most manufacturers of inboard rotary pump espresso machines mount them on squishy rubber footings, arresting the little vibration the pump produces.

I assume the whirring sound you hear is not from the pump itself, but sound produced by sympathetic vibration. Mounts that are made of too hard a rubber, not enough rubber, components touching each other, etc. can result in odd buzzing that is very difficult to locate. As a case in point, the original La Spaziale S1 rotary pump mounts were replaced by slightly softer rubber in the final production model. I retrofitted them in during the final weeks of testing and was astounded by the noise level reduction. So the answer to your question "Should a properly functioning rotary pump be silent, near silent, or make a whirring sound?" is regrettably "it depends."

[AndyS]

I assume the whirring sound you hear is not from the pump itself, but sound produced by sympathetic vibration.

I think there's a lot of difference in the amount of noise produced by the various electric motors that drive the rotary pumps.

[mhoy]

My old Francis!Francis X5 was very quiet in comparision to my Anita. (This is even after a fairly major attempt at quieting my entire system down by putting Dynamat through out the inside). Of course the Anita is WAY better at espresso. I turned on an Elektra that I'm rebuilding and wow, the rotary is WAY quieter than the Anita and the X5.

Mark

[shadowfax]

I have a vetrano, and it's usually fairly quiet. However, every now and then, I pull a shot and there is this very quiet, low-frequency vibration that sounds like the pipes in the system. It's fairly quiet, but very aggravating--It kinda sounds like something is damaged or in the process of getting there.

I understand that this is somewhat common on QM machines, which is kind of disappointing. I have been meaning to ask if there is an easy fix for this, or even a mildly painful one.

[hbuchtel]

(...) stood next to a Nouva Simonelli Mac Digit as a few shots were pulled. (...) visited a brand new (hence nearly empty & quiet) coffee shop in my area. When the barista switched on the pump, I heard nothing.

Hello David, do you know if the other machines had external pumps? If they were under the counter it would be a lot quieter.

Henry

[dmankin]

Hello David, do you know if the other machines had external pumps? If they were under the counter it would be a lot quieter.

Henry

Henry,

Only the machine in the coffee shop had an external pump - The Mac Digit, my friend's Rancilio & my Bunn all have an internal rotary pump.

David

[hbuchtel]

Henry,

Only the machine in the coffee shop had an external pump - The Mac Digit, my friend's Rancilio & my Bunn all have an internal rotary pump.

David

Cool. Wonder what it is then? Some of my favorite extraction videos are from Dan's "week with the GS3" thread, in most of them the solenoid clicks are louder then the motor...

I used a CMA commercial machine for a summer and the motor (or pump?) was fairly loud.

Henry

[erics]

My question is this; Should a properly functioning rotary pump be silent, near silent, or make a whirring sound?

David -

Of your three choices, the most correct answer would be near silent. A whirring sound is, to me, indicative of a bearing(s) (motor or pump) getting tired. That said, it may very well be easy to mechanically disconnect the pump from the motor without loosening any water line connections. Hey - this could be a practice session for your rebuild If you shoot some pics with a camera, I'm fairly certain you will pick up the audio also. Do all of this with the machine at room temp.

The inlet and outlet connections on the pump should both be something other than hard piping but make sure they are not putting any stress on the pump housing. The noise resulting from cavitation (poor inlet conditions for the pump) could also loosely translate into a "whirring" noise. What sort of pressure do you maintain at the inlet to the machine during operation? Or better yet, what pressure does Bunn want you to have and do they have specific installation instructions for this machine?

Some other checks not necessarily connected with "whirring" would be the condition of the mounts for the motor and the tightness of the mount fasteners.

edit - added pump mfg install notes:

http://www.fluid-o-tech.com/files...eet_PO030-1000.pdf

http://www.proconpumps.com/PDFs/I...20Instructions.pdf

[dmankin]

...That said, it may very well be easy to mechanically disconnect the pump from the motor without loosening any water line connections. Hey - this could be a practice session for your rebuild If you shoot some pics with a camera, I'm fairly certain you will pick up the audio also. Do all of this with the machine at room temp...

Eric,

Thanks for your comments. It's sort of a long story, but in trying to stop my pump from leaking around the pressure adjustment screw, I overtightened the locking bolt and.. um... broke the thing. I STRONGLY believe that the pump was nearing its end, since it was putting out 5 bars when recently checked with a reliable gauge, and when I increased the shot pressure to acceptable levels, the leak became more substantial.

I am going to try to pull the pump out tomorrow in order to have it rebuilt, so I'll be sure to engage the the motor w/o pump to see how quiet or noisy it runs. The pump has to go out anyway, so noisy or not, I have a busted pressure adjustment screw & it will need to be replaced/rebuilt.

BTW, I'm just down the road from you, so if you ever find yourself on the Virginia side, there's a shot of espresso or three for you - assuming I get the Bunn ES-1A back up and running!

Here's a video of my machine BEFORE I killed the pump! My digital camera doesn't do sound very well, but you can get an idea of the type of sound she made.



Thanks again, Eric

David

[erics]

Another thing to think about, although it might take a little bit of work, would be to TEMPORARILY mount and run the new pump/motor outside of the machine initially. If you need a copy of the Bunn manual (pdf), email me at erics@erols.com

If your machine is as described in the manual, it has hard piping (copper tubing) connected to both the inlet and outlet of the pump and, personally, that would be one of the first changes I would make in addition to soft mounting the motor unit.

[mhoy]

Erics: What does one use for a soft mount instead of copper?

[erics]

For David's Bunn ES-1A, I was "working" with what I saw in the operation/service manual. It indicates copper tubing vice teflon or SS braid over teflon for the connections to/from the pump. Actually, his machine is technically correct in that the motor/pump appears to be hard mounted and the connections are "hard". If a motor/pump were soft-mounted, one would typically NOT have hard connections between the pump and machine components.

Doing a search on the McMaster-Carr website for "sound isolation mounts", there is a myriad of choices for the pump/motor unit. As far as connections between a soft-mounted pump and a machine, a flex connection, transitioning to metallic tubing would seem appropriate.

[LeoZ]

Vibratory pumps get a bad rap because... they vibrate. If you run one free from an espresso machine's casing, it makes less noise than an electric razor. Alas vibratory pumps do indeed vibrate, producing a tinny reverberation of interior components. I'm not making this up, I "outboarded" mine and the noise level is about the same as an inboard rotary pump:

how outboard is outboard? i dont know the specs of vibratory pumps, but id be nervous to run out of head with even a couple feet of extra hose on it.. you notice anything loss of pressure with the setup?

[HB]

The pump is directly beneath the machine in the cabinet below. In years of use, I've never had a problem (*). I believe vibratory pumps are technically spec'd at zero inlet pressure and mine is supplied 20 PSI, so I'm already off the reservation. It seemed worth the risk.

(*) Oh great, my saying that assures the pump will fail the very next time I use it.

[markr]

how outboard is outboard? i dont know the specs of vibratory pumps, but id be nervous to run out of head with even a couple feet of extra hose on it.. you notice anything loss of pressure with the setup?

I outboarded the vibe pump on my Brewtus last night. I'm running it through 1.5m of braided hose similar to that shown in HB's photo with the pump on the floor beneath the machine, so a vertical lift of around 0.9m. Pressure at the brewhead was identical to that measured before the outboarding. I have no idea if this is straining the pump or not, but I see this as a step towards replacing the vibe with a rotary and plumbing in fully anyway, so I'm not too concerned if it dies earlier as a result.

[dmankin]

Well, I successfully removed my pump today. Here's a photo of it, where you can clearly see where the adjustment screw snapped off, as well as the obvious leak location.



Tomorrow, I'll try to run the motor alone to see how noisy it is without the pump attached.

David

[erics]

David -

See this: http://www.depcopump.com/datashee...rotary%20parts.pdf

I'm thinking that Fluid-O-Tech and/or their distributors have rebuilt units in stock in the event you do not have sources.

[dmankin]

Thanks, Eric. I plan to send the pump to J C Beverage in Minnesota for a complete rebuild. They charge $43.50, which seems more than reasonable to me. The rebuilding of the pump will fix my leaking pump problem, but there is still the issue of sound to address.

Check out this video of my motor running without the pump attached - by no means silent, or even close! Is this abnormal? Acceptable? Can one lubricate a noisy motor? I can rest just fine with the machine's noise level, but I really want to figure if this machine is meant to be this loud, or did it come from the factory nearly silent and has worked its way to this point.

Thanks for all your input.
David

[erics]

Good choice on the pump rebuild - I had read about them in another post - maybe CG - and was trying to hunt them down for ya but . . .

I can't comment on the motor noise other than to say it does not sound like a motor bearing problem but, at the same time, DOES NOT sound normal. I would liken it to a transformer (coil) hum or whine.

Maybe a new post (with different subject heading) with this same video would attract an electric motor guru.

I see that the motor is soft mounted - good - but was there any flexible piping between the pump and the machine?