Volumetric dosing doens't work

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MarkM
Latte
Posts: 11
Joined: Fri Jun 05, 2020 6:35 pm
Location: UK

Volumetric dosing doens't work

Post by MarkM »

I ran some tests today and observed this...

All 20g weighed coffee, same batch.

Set the volumetric dose at 42g (weight)

Here are the weights of the subsequent shots:

43g
31g
30g
31.7g
32.2g
22.2g

So I thought I'd do it with no portafilter in and see what is coming out:

113.6
112.7
107.6
106
107
104.8
95.9

So why such inconsistencies? Also generally decreasing each time.
DonTask
Freeze Dried
Posts: 2
Joined: Mon Jun 15, 2020 4:03 pm
Location: North Carolina

Re: Volumetric dosing doens't work

Post by DonTask »

I experienced a similar problem with an older volumetrics dosing machine I had. Found a rather informative article (albeit dated) on Volumetrics which helped me identify the problem.

NET: In my case I had to change out the flow meter due to internal scale buildup from hard water. Your problem could also be something as simple as a loose electrical connection at the wire connecting to the flow meter. If not, and you don’t have hard water it might simply be a sticking impeller (PN 3707) or malfunctioning meter assembly. FYI: For reference I included a shot of the flow meter from the S1 parts catalog. I’m not sure if you can easily order the individual parts shown but it might be less expensive than replacing the entire flow meter.
S1 Flow Meter.JPG
S1 Flow Meter.JPG (14.8 KiB) Viewed 3299 times

What follows below is a direct quote from the article (see the next to, the last two paragraphs from this article:
https://www.lamarzoccousa.com/blog/ben- ... lumetrics/

"The performance of the flowmeter does, of course, degrade over time. All parts eventually fail and need to be maintained or replaced, especially those in constant contact with water. In all likelihood, you live in a place that has water that is softer or harder than is ideal for the performance of the espresso machine, the flowmeter, and the flavor and extraction of the coffee."

"Generally, near-ideal water has approximately between 65-85ppm in CaCO3 as a subset of total water hardness. That translates to between 4-5 grains per gallon if you’re in the United States, and just about the same number of German degrees hardness if you’re anywhere else7. This is definitely something to keep in mind when using a volumetric espresso machine, as hard, untreated water will rapidly degrade the performance of a flowmeter by formation of scale within the system."
Velcro
Macchiato
Posts: 46
Joined: Tue Mar 06, 2018 5:28 pm
Location: PA

Re: Volumetric dosing doens't work

Post by Velcro »

I had a similar problem and cleaning out my flow meter fixed it.
Its been very stable since
Velcro
Sette 270
La Spaziale Dream v1.24
IMS Baskets & Reg Barber C-Flat 53.3
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