another_jim wrote:[quote="malachi"]I understand how this would seem to bias against HX machines, but the reality is that this is all designed for evaluating machines for the WBC - and for the WBC it's unrealistic to have machines that require some specific and varying flush methodology.
The test does not reflect WBC use, which is to pull 3 shots at each group at roughly around 2, 5, and 9 minutes into the presentation, with the final two rounds having looser requirements from the taste point of view since they are being used as the base for other drinks. Moreover, if an HX machine is used, you'd want to know how much to flush it for those intervals, and especially for the initial espresso shot. Presumably, the test data would be available, and you could use it as you please.
Suppose someone does submit an HX machine with a grouphead sensor, and the user instruction is to flush until the sensor reads, say 0.5C higher than the desired shot temperature. If you then insist on the flush amounts in the protocol as written, the manufacturer would say you are in effect disabling the final temperature control. Now suppose he resubmits it with the sensor hooked to the autodosing, so the machine flushes automatically to a set temperature, and won't run with the PF mounted till it's there. Do you disqualify the machine entirely? No matter how you answer these questions, the fixed flush part of the standard looks more and more absurd.
Let me be completely blunt here. You can stick with this standard and LM as the sole supplier; and everyone will be happy. But I cannot see any HX manufacturer agreeing to it; and I cannot see it as a good faith step for creating an open competition for manufacturers:
1) The measuring protocol in effect prescribes how the machines are to be operated.
2) One of the co-authors is Bill Crossland of LM.
3) The operating instructions closely follow good barista practice on LMs and only on LMs.
I used to work for a company that bid on process and HVAC control jobs. We called specs like this proprietary, and assumed it was ghost-written by the favored company. We loved it when we were doing the ghost writing; and made a big stink when it was another one. In the end, unless the fix came from upper management, the engineer in charge of writing the spec usually ended up fired.[/quote]
Actually Jim, we had philosophical reasons for writing it this way. We think that the ideal machine would exhibit the same thermal performance off idle compared to full-tilt boogie. We think it's reasonable to write the standard in a way that allows us to examine off idle performance without flushing. It's not fair to force competitors to play on something that doesn't require specialized experience with the machine to begin with unless everyone gets lots of time on the machine. Why does art of running an inferior machine trump the art of the coffee? The machine for next year was selected partially on that basis. Currently, no manufacturer of hx machines installs flushing thermometry in its machines, so it's a moot point for now. Currently there is no good information re flushing specific machines. Are you suggesting that this get turned into more of a research project than it already is? IF a machine manufacturer doesn't like the results after the tester performed the manufacturer's flushing ritual, are there then going to be claims of "you didn't do it right"? From our perspective it's just better to do it as we wrote.
I disagree that the deck is stacked by the authors. The authors of the standard are reasonable people to do the job. I work in applied thermometry. John Sanders is head of the WBC technical standards committee. Barry Jarrett is very capable, understands instrumentation and has experience with a wide variety of machinery. Bill is a good mechanical engineer with wide experience who agreed to help work on this. From my perspective, his working for LM doesn't mean squat wrt this standard. He knows a lot about coffee machines in general. In our view, and in our experience so far, the measurement method does expose the warts of various machinery. Our work is also supported by the other members of the technical standards committee, who adopted the standard.
Your item 3 is just plain incorrect. If you perform this measurement procedure on a LM Linea you will learn that this procedure is not good barista practice on that machine as well. However, the procedure shows what the weaknesses of the Linea are, gives you a clue about what to do to compensate and also gives you good information about the ultimate capability of the Linea.
You should know that one heat exchanger machine submitted to the WBC had extremely good reproducibility over all duty cycles, when measured using this method. In fact, it had the best reproducibility of all machines submitted. It was not selected for other reasons.
Jim, have you made some measurements of machinery using this method? If so, I'd love to see your results. If you have extensive experience with the machine, does the measurement procedure give you information about how to use the machine that reflect your experience?