Thursday, April 18, 2013

Electric Hot Liquor Tank Regulator

Having an engineer as a friend can have its rewards.  My friend John, the one who I brew beer for his summer party, has come up with a new gadget for the homebrewery.  I like to fly sparge, which means balancing a slow flow of hot water out of the hot liquor tank (HLT) into the top of the mash tun, while allowing wort to trickle out of the bottom of the mash tun.  The hot water slowly rinses the grain bed of additional sugars, a process that mimics what is done at the professional brewery scale.  However, the flow rates must be adjusted during the 45 minute sparge because of the changing head pressure from the HLT as it empties (I use a gravity feed).  Having witnessed the many adjustments, John has designed a gadget to automate the adjustments.

The gadget has a rather simple concept.  It uses two metal wires that are mounted close together and suspended over the mash at the desired height of the mash column.  As the sparge water flows into the mash tun and the level rises, it eventually contacts the two wires.  This completes a circuit that closes a valve and blocking the HLT port.  As the mash tun drains, the water level goes down and breaks the circuit, thus opening the valve and allowing the sparge water to flow again.  This is all powered by a "wall wort" that came from an old electric keyboard my wife used to play.

In a way, the mash acts as a switch.  John has explained it in detail to me, but most of it is over my head.  My understanding of circuits does not extend much past the light bulb and battery circuit experiment I did in 4th grade.  But, I can say the gadget is really quite cool.

The prototype is currently on version 3.0.  The main problem we have had so far is the size of the electrical valve's aperture.  The first two versions used valves that were not large enough, mainly because John scavenged them from other projects he has worked on.  Now that we have a good idea of flow rates and how the gadget works in practice, we will pick up a valve sized for the job.  Other, more minor adjustments have included how to mount the gadget and how to secure the probe wires.  Once these are complete, we still have to figure out how to put it in a durable package so that it can be protected for years to come.

Thanks for the idea and all the hard work, John.  I look forward to many more years of gadgets to come.



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