Scace Thermofilter Temperature Device - Page 2

[gscace]

My point is that fixing flow rate, as Greg has done here, may not be a good idea for that very same reason. Different shops use different flow rates for their extraction, and different pressure. Without an adjustable flow rate valve, this is becoming a problem. That is of course if you want to be precise within a tenth of a degree.

Different shops may use different flow rates, but the point is to provide a standardized methodology that remains consistent. If a shop wants to brew at 10 bars rather than 9, then the flow rate will be higher, but it will be constant to within a couple of percent for a constant brew pressure and reasonable amount of temperature variation. Dunno how much you've used it yet, but I think you'll find that espresso machines are way less reproducible than 10ths of a degree, even though the thermofilter has precision that is on that order. It's also important to realize that for an espresso machine to work well, the design is gonna have to be robust enough to be stable for more than 25 seconds +- 5. If it can't be stable for 30 then it won't reproduce temperatures in any duty cycle approaching continuous duty. So reproducibility seems to me to be more important than nailing a precise volumetric amount, as long as the volumetric flow rate falls within the standard for espresso.

Variability in flow rates is possible using needle valves, and I tried a bunch of em. There are very expensive, require pre-loaded stems to keep thread backlash from affecting flowrate, and less repeatable than the orifice, which behaves very repeatably. In my way of looking at the problem, repeatability was a more useful objective.

-Greg (If it's still off at 9 bars, lemme know and I'll change out the flowmeter for you)

[gscace]

It could also be coffee clogging the exit hole. Greg, how do you clean it and release a clog?

Bob will be the first one to clog up a filter if he has done so. Bob, was your machine clean?

Answer is to remove the orifice from the filter and flush it out. Look thru the hole at a light source to see if it's clear. Don't try running any wire thru it because it's really tiny. You should also flush out the filter. Water should easily flow through it.

I'll include the need for clean machinery in the instruction set. We hadn't plugged one up with the filter in place but there's always a first I guess.

-Greg

[Abe Carmeli]

Variability if flow rates is possible using needle valves, and I tried a bunch of em. There are very expensive, require pre-loaded stems to keep thread backlash from affecting flowrate, and less repeatable than the orifice, which behaves very repeatably. In my way of looking at the problem, repeatability was a more useful objective.

If flow rate is mostly controlled by the orifice diameter, perhaps you can modify the orifice size to fit pressure variation, and offer 3 options: 8.5; 9; 9.5 bars. That will give a coffee shop the ability to measure brew temp using their specific pressure environment. If it is more than just orifice size, it gets more complicated.

[DavidMLewis]

It's a good idea at first blush and one that I've tried out. The problem is that the internal volume of the plumbing gets so large that the espresso machine dumps a bunch of water out into the thermofilter on startup, which doesn't reflect what's going on when brewing. So until I can get the internal volume down it's gonna be a temperature only device.
-Greg

Hi Greg,

I think the key may be that you don't need to measure temperature profile and pressure at the same time. You could, then, have an instant tube fitting coming out the bottom of the unit, and use a plug when you weren't measuring pressure.

Best,
David

[gscace]

Hi Greg,

I think the key may be that you don't need to measure temperature profile and pressure at the same time. You could, then, have an instant tube fitting coming out the bottom of the unit, and use a plug when you weren't measuring pressure.

Best,
David

Ah yes. Nice idea. Back to the basement I go. The basement is pretty fun these days. Not only are there a zillion parts for thermometers, but I have like 6 grinders in there, the Linea 2-group, an Astra Pro, and a Concept 2 ergometer. One of the grinders is a new conical burr Mazzer Kony. Hmmmm. I digress. This is the thermofilter thread. Thanks for the great idea!

[BobY]

It could also be coffee clogging the exit hole. Greg, how do you clean it and release a clog?

Bob will be the first one to clog up a filter if he has done so. Bob, was your machine clean?

Answer is to remove the orifice from the filter and flush it out. Look thru the hole at a light source to see if it's clear. Don't try running any wire thru it because it's really tiny. You should also flush out the filter. Water should easily flow through it.

I'll include the need for clean machinery in the instruction set. We hadn't plugged one up with the filter in place but there's always a first I guess.

-Greg

The problem was, indeed, a clogged orifice. I cleaned the machine's group shower head and back-flushed several times before beginning the measurement sessions but didn't do an Urnex clean-out. By the end of the three hours, the flow rate went from 2.25 oz/25 seconds (as-received, brand new condition), down to 1.25 oz/25 seconds.

I tried putting the pf under running water to clean out the filter but the flow rate remained at 1.25 oz. Then, instead of removing the orifice, I took some 30 AWG (0.010 inches) silver-plated copperweld (copper-clad steel) wire and cleaned the orifice. This size is smaller than the orifice diameter and after that all went back to normal: from 1.25 oz. before the cleaning to the original 2.25 oz immediately afterwards.

Problem solved. But what about those who don't do these measurements with a squeaky clean machine? I guess the planned info sheet including something about the device's sensitivity to clogging will be very helpful.

BobY

[barry]

The problem is that the internal volume of the plumbing gets so large that the espresso machine dumps a bunch of water out into the thermofilter on startup, which doesn't reflect what's going on when brewing.

how about using a capillary tube for the pressure gauge hookup?

[barry]

and brass-colored metal "filter material" inserted in the pipe,

whoo-hooo!



--barry "my contribution"

[barry]

Problem solved. But what about those who don't do these measurements with a squeaky clean machine? I guess the planned info sheet including something about the device's sensitivity to clogging will be very helpful.

it should not be necessary to use a squeaky clean machine. the filter in there should trap just about anything that isn't dissolved.

i wonder if there's an issue with material precipitating out on the orifice rim.

[BobY]

it should not be necessary to use a squeaky clean machine. the filter in there should trap just about anything that isn't dissolved.

i wonder if there's an issue with material precipitating out on the orifice rim.

The problem was solved by inserting a fine gauge (30 AWG) wire into the orifice without any cleaning of the filter. Then yesterday, after a machine cleaning with Urnex and a soak of the pf sans end cap (orifice) I started again. I got about 30 straight shots with a flowrate of 70 ml/25 sec.

Then, inexplicably, the flowrate suddenly dropped to 60 for a couple of shots. I inserted the wire and once again. another few dozen 70 ml shots (dead nuts every single time). I'm not sure what could be precipitating. The water here is very (too) soft, and in the years that I have done occasional descalings of Silvia and, for the last year, the Andreja, I've never seen a single hint of scale.

It could be that a grain of coffee or something else was freed up from the filter and drifted down to the orifice. But when there is no obstruction, the device is working like a laboratory instrument; as close to perfect as I would ever need.

BobY

[BobY]

Part 3

Some of the data from my bench testing was gathered before cleaning my machine with Urnex and some afterwards, with consistent results. In this part, I will show some date collected to test the ease of setting up common shot-pulling routines on an E-61 HX machine. Without boring readers with all the data on all the various tasks that I tested, these two are of prime interest to E-61 HX users:

1. An initial flush after an extended rest period to ready the machine for pulling shots (eliminating the "water dance" method).
2. Set up of a routine that will produce consistent temperatures, shot after shot by observing the time between shots.

For the data shown below, I should note, that in normal use, after a shot is pulled, more HX water is used to clean the shower screen, etc., so one does not normally run consecutive shots as I did in this test. But the purpose in this specific test was to demonstrate that I could quickly get consistency and accurate results using the TTD, rather than trying to exactly duplicate my normal routine. Later, I did indeed, easily manage to zero in on a flushing routine that fits my specific espresso-making habits.

In the examples below, I picked 199 deg F as a general target shot temperature. This temperature produces a desirable shot from certain of my beans and is a good average between 203 F and 195 F, the range I am likely to use in practice. The dip seen between shots in the first graph is the removal of the pf from the group head to relieve pressure, dump out water and for other reasons.

The first graph shows an initial flush after about 20 minutes of machine rest, from about 209 deg F down to about 196 F. That took one minute (5.4 oz.) through the device and was my pre-determined flush to set up a 199 deg F shot temperature after a 3-minute wait. The next graph shows the 25-second shot, three minutes later.

The next graphs show the use of time between the shots to control consistency. The two graphs show the first and third shots in a series. Very good consistency is quickly, accurately and easily achieved.

The final installment will compare this device to the use of another pf with an embedded TC using both a sponge to simulate the flow and coffee, in the basket.

BobY

[BobY]

The two dips seen below are due to pf removal from the group head between the flush (beginning of the chart) and the 25-second shot (end of the chart).





First and third shots of a long series of consistent-temperature shots.

[Abe Carmeli]

Bob,

Just to make sure I fully understand your usage of the Portazilla (my nick name, and I hereby place it in the public domain). You use it to develop a flush chart that will be tied to idle time. Like my Giotto flush chart?

[gscace]

Bob,

Just to make sure I fully understand your usage of the Portazilla (my nick name, and I hereby place it in the public domain). You use it to develop a flush chart that will be tied to idle time. Like my Giotto flush chart?

It's one of a number of uses for it.

-Greg

[BobY]

Bob,

Just to make sure I fully understand your usage of the Portazilla (my nick name, and I hereby place it in the public domain). You use it to develop a flush chart that will be tied to idle time. Like my Giotto flush chart?

If you're asking about my personal usage, my goal for now is just to bench test this device. Ultimately I will use it for multiple purposes including the development of a routine where I can get reasonably close to predicting what the temps will be without the use of any charts. That will be one of my personal goals. What others do with it is up to them.

BobY

[barry]

It could be that a grain of coffee or something else was freed up from the filter and drifted down to the orifice.

the filter is a 40 micron sintered bronze filter; no coffee grains should be finding their way to the south end at all.

other possibilities: swarf from drilling the orifice, and stray filaments of teflon tape.

i'm really interested in nailing down what's happening here.


--barry "if the filter ain't filtering, i wanna know about it"

[gscace]

It could be that a grain of coffee or something else was freed up from the filter and drifted down to the orifice.

the filter is a 40 micron sintered bronze filter; no coffee grains should be finding their way to the south end at all.

other possibilities: swarf from drilling the orifice, and stray filaments of teflon tape.

i'm really interested in nailing down what's happening here.


--barry "if the filter ain't filtering, i wanna know about it"

Yeah, I mentioned that it might be teflon tape, but I didn't mention swarf. And I like to say swarf too. Swarf Swarf Swarf Swarf Swarf Swarf Swarf!

-Greg "also in knowing the root cause" Scace

[erics]

It's worth my looking at because the measured pressure reflects the pressure when pulling shots, rather than the pressure against a blind filter. On my Linea, the difference is around 1 bar, which surprised me.

-Greg

Interesting. After reading our various "how to adjust vibe pump posts," some people complained when the found their brew pressures were 1/2 to 1 bar below their blind pressures. I guess this is a characteristic of OPVs rather than the pumps they regulate.

If the drop from blind to flow would be constant across all machines, shot flow rates, and OPVs, it would be no sweat. Just set it by the blind filter and everyone will get the same result. However, if that creates different actual brewing pressure for different machines and shots, then setting pressure with metered flow from the group also become very desirable.

For Greg Scace - great display of a lot of ingenuity in your temperature measuring device. As far as measuring pressure is concerned, a neat way to do this would be to install a 1/8" NPT sampling adaptor (I believe Parker is the source) with plug and corresponding "needle" adaptor which slides through a self sealing neoprene plug. I have some left over from my engine engineering days in the event you want to try them. Understand your concerns about the volume matter.

For Another_Jim - thanks for your many thoughtful contributions to the coffee sites. Checking pressure (intentional omission of setting/adjusting) while having a metered flow is, IMO, essential. The difference in pressure measurements is due to the delta P experienced by the water as it flows through the "system" wherein a large contributor to this pressure drop is the three-way valve.

Eric S.l

[BobY]

Yeah, I mentioned that it might be teflon tape, but I didn't mention swarf. And I like to say swarf too. Swarf Swarf Swarf Swarf Swarf Swarf Swarf!

-Greg "also in knowing the root cause" Scace

For those of you who, like me, don't (didn't) know what "swarf" is...I looked it up:

Swarf refers to the mixture of broken-off abrasive, metal filings, and lubricating liquid that results during the sharpening process. Abrasive breaks off of the sharpening media, such as a grinding wheel, waterstone, or sandpaper. The metal filings are the "scratched-off" material from the tool being sharpened. The lubricating liquid could be water or a cutting oil.

Bob "now I know what swarf is" Y

[barry]

Swarf refers to the mixture of broken-off abrasive, metal filings, and lubricating liquid that results during the sharpening process. Abrasive breaks off of the sharpening media, such as a grinding wheel, waterstone, or sandpaper. The metal filings are the "scratched-off" material from the tool being sharpened. The lubricating liquid could be water or a cutting oil.

it's the slivers of brass/steel/aluminum that end up in my foot when i walk around the basement w/o shoes on.


--barry "doh dee doh dee doh d'OWW!"