Distiller's Parrot: Electric vs. Conventional & Alchometer
A conventional proofing parrot (for distilling purposes) is a small, cylindrical collection vessel that catches distillate long enough to get an “on-the-fly” measurement of ABV being produced in real time.
How a Proofing Parrot Works
The reservoir on the proofing parrot allows the distiller to drop in a hydrometer for measuring the density of the distillate being produced. Ordinarily, this ABV measurement is only used to assist the distiller in determining if the still is performing accordingly. The on-the-fly measurement also helps the distiller determine how much more alcohol might be remaining in the distillation apparatus over the duration of the run.
During this time, the accuracy of the ABV measurement is not supercritical and indeed will not be precise at all. What is perhaps more important to the distiller is to be able to determine when a change in the quality of the distillate occurs. Kind of like the oil pressure gauge in grandad’s old pickup truck, accuracy isn’t nearly as important as consistency. If the pressure needle on the truck's gauge moved away from its customary position, grandad knew the old pickup needed some attention. So that’s really the only degree of accuracy needed at the discharge end of the proofing parrot.
The rub here is that even though fresh distillate enters from the bottom of the reservoir and exits from the top, there may very well be some distillate trapped in the reservoir that is several minutes old. This lag in the distillate turnover rate can be more problematic on small, experimental / recipe development batches as the transition from heads to hearts does happen more rapidly. Some operators try to overcome the turnover lag by utilizing the smallest possible diameter on the cylindrical collection reservoir to minimize the liquid volume. However, the issue with this is that the smaller diameter doesn’t cope with all ranges of collection speed. More rapid collection speeds can increase the throughput speed of the distillate as it travels through the cylinder, and the result is that this creates hydraulic lift on the floating alcometer and causes an inexperienced user / distiller to assume the ABV is actually higher than it really is.
Ultimately, the conclusion here is that an inline alcometer reading is rife with inaccuracies, if accuracy matters.
The Advantages of an Electric Distiller's Parrot
A good way to close the gap on those inaccuracies if shooting for an on-the-fly ABV measurement is to use an electric distiller's parrot. The StillDragon electric parrot has several benefits over a conventional proofing parrot, including an easier read out, faster response time, no temperature conversion required, no reservoir of liquid to risk smearing, and no glass smashing. The StillDragon electric distiller's parrot takes the vapor temperature and runs it through a microcontroller that runs a few conversions. Basically, the temperature of suspended vapor in a distillation apparatus has a direct relationship with the ABV of the resulting distillate. Have a look at an ethanol phase diagram to get a better understanding of how vapor temperatures equal ABV. As long as the user / distiller gets a good vapor temperature reading, the ABV reading is solid.
“With a Cooling Management system, the probe installed just above the dephlegmator may be the easiest. Or if you need a reading at 100% RR, then just below the dephlegmator with something to protect the sensor from reflux is fine too. For Vapor Management take off, just under the take off. And anywhere in the head for Liquid Management as long the probe is shielded from cold reflux.”
No on-the-fly measurement will ever be 100% accurate. Even a much higher priced, matching set of electronic density meters has a margin of error on a side-by-side ABV test. Hopefully this article has explained enough about the functionality of proofing parrots so that you’ll understand the reliability and liability issues with using either type of measuring device.
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