Hailing from a new brewery in Nashville, the Troubleshooter again comes to the aid of the troubled and just plain curious.

PRESSURE VS. VACUUM FOR STARTING SIPHONS

The vacuum device that I'm currently using is a toy called "The Sucking Thing." It would work OK if the squeeze bulb didn't collapse from the vacuum after a few squeezes. I've changed bulbs to a sturdier one I took from a baster, but the operation is still marginal. Do you know where I can get an adequate, inexpensive, hand-held, hand-operated vacuum pump? I know of a $50 model that draws 35 mL/stroke . . . seems like a lot of $/mL (and a lot of strokes). I would also love to find a cheap dispenser that accepts carbon dioxide cartridges for use in purging the receiver carboy of air prior to racking, without the expense of a carbon dioxide tank, regulator, and so forth.

Can you help?

Finally, on a different subject, I infer from your discussion of pH (also in the July/Aug issue) that readings on meters with automatic temperature compensation (ATC) are referenced to 60 °F (16 °C). Is that really what ATC means?

DM: Lots of interesting questions. First off, yes, a vacuum is safer than pressure, because when you start a siphon by using a vacuum the carboy is not sealed; the mouth of the carboy has to be open so that air can be drawn into the vessel as the beer is siphoned out. On the other hand, when you start a siphon using gas pressure, the headspace at the top of the carboy must be sealed to give the beer a push. Of course, once the beer starts flowing, you should immediately unseal the carboy and shut off the gas.

I am sorry to hear that your vacuum device does not work acceptably. I hope you have discussed this with the manufacturer, who should be in the best position to modify the design so the thing will work.

I have two things to say about using gas pressure to start a siphon. The first is that I do not advise it. It is inherently risky because carboys are not pressure vessels. With a standard gas cylinder and regulator, you can quickly build pressure in the headspace up to the point where you burst the carboy. Your racking hose imposes a fair amount of restriction on the beer flowing out of the carboy, and you can push gas in a lot faster than the beer can flow out. Hence the very real danger of a burst carboy and serious injury.

From a liability standpoint, I probably ought to stop there. Safety is the reason I never mention the gas-pressure siphon starting method in any of my books. However, I know that some people are going to try this in spite of my warnings. So without recommending it, I can tell you how I would use gas pressure to start a siphon if somebody put a gun to my head and told me to do it. I would set the secondary pressure on the regulator down to only 1 psi - no more - which should be sufficient to move the beer up the racking tube and into the racking hose. Once I saw beer in the hose, I would immediately pull the stopper out of the carboy and shut off the gas.

Once again, I don't recommend using gas. It is dangerous. I told you so, and if you end up cut or blinded don't come blaming me. Stick to vacuum and you're safe. If you are determined to try the pressure method, you do so at your own risk. Even though you are doing something inherently foolhardy, at least keep the pressure as low as possible.

All told, your only safe course is to find a cost-effective way to use a vacuum to start the siphon. I agree that the vacuum pump is too expensive, and sucking on the tube is unsanitary (though I did it for years and never caused a lactic acid infection), but gas pressure is not a good alternative, unless you switch to using pressure vessels (soda or beer kegs) as fermentors.

On the subject of gas bulbs: there are some devices around that take a standard carbon dioxide seltzer bottle cartridge. They are designed to inflate motorcycle tires. Some of them appear to have (I have not had the chance to examine one closely) a valve that allows you to control the flow of gas. None of them, however, regulates the pressure of the gas flowing out of the device. This is acceptable for the intended application, but it makes them totally unsuitable for any use in siphoning. They might be useful for filling an open carboy with carbon dioxide before filling it with beer. But gas bulbs are expensive, and the replacement costs will quickly (probably within a year, if you are a serious home brewer) eat up your initial savings. When you consider how many uses they have, a small gas cylinder and regulator is a better option.

On ATC and pH meters, see the answer further on.

COLD TRUB AND pH METERS

On another topic, could you direct me and others to a correction table, or formula, that can be used with pH meters that are not temperature compensated?

DM: There is a lot of debate about the importance of removing cold trub. In general, British ale breweries do not remove cold trub. Lager breweries often attempt to remove it, though they have found, as you have, that total removal is not possible without expensive equipment (such as wort filters or centrifuges). The general consensus of the research I have seen is that, for lagers, partial cold trub removal gives better results than either total cold trub removal or no cold trub removal. For a detailed discussion of cold trub removal, see reference 1.

Only a few breweries supercool their wort (that is, cool it below primary fermentation temperature) before pitching yeast. Most brewers feel it is important to pitch the yeast as soon as possible after cooling. No matter how sanitary the equipment is, you still are relying on your yeast to push aside those last few bugs that inevitably get into wort. I believe that a lot of the fine, wispy cold trub you can't remove is formed during your overnight supercooling stand in the freezer and that you don't need to worry about it.

I suggest modifying your wort cooling procedure, perhaps by using ice water in your counterflow wort cooler so that you can bring your wort down to the selected pitching temperature during its passage through the cooler. Then pitch your yeast and aerate the wort immediately. To remove cold trub, dead yeast, and so forth, rack the beer into the primary fermentor about 4-12 h later - just when you see the first signs of fermentation. This method works well with home brewing equipment and removes sufficient quantities of cold trub.

One technical problem you may have with implementing this program is that you may find that you need to control the flow of wort and/or water through your cooler to get the desired wort temperature coming out. This may require putting a valve or two in the lines. You sound like an intrepid type, and I'm sure you'll have no trouble making these modifications.

On the subject of pH meters: I do not have a correction table and in truth have never seen one in print. I have always used ATC pH meters, which contain a temperature sensor built into the probe along with the pH electrode. The temperature sensor provides input for a feedback circuit that corrects the reading to reflect what it would be if you cooled the wort to room temperature (60-70 °F, or 16-21°C). It is important to understand, however, that the actual pH in the mash tun is lower than the reading given by the ATC meter. In other words, the true pH of the mash depends in part on its temperature. So ATC is kind of a mixed blessing. When you use it, you have to then remember that the actual pH in the mash tun will be 0.2-0.3 lower than your readout.

So, why use an ATC meter at all? Mostly because all good meters these days come with ATC, so you don't have much choice once you get to a certain level. Also, with an ATC meter, you are assured that the probe is designed to withstand a certain temperature - the maximum stated in the specifications for the unit. I wouldn't trust the readings of a cheap pH meter stuck directly into a hot mash, because the instrument was not designed for high temperature use. If I had to use such an instrument, I would cool a small sample of the wort to room temperature as quickly as possible before taking my reading.

JOCKEY BOXES AT HOME

DM: The only published information I know of on jockey boxes is an excellent article by Teri Fahrendorf in the Fall 1991 issue of zymurgy. The article focuses on construction of the jockey box, but also covers operation. This article will answer most questions you would have on its use.

I would add only a few things to what Teri wrote. First, her suggested operating pressure of 22 psi is too low for the commercially built jockey boxes that I have worked with. 45 psi was more like it. The required pressure, however, depends on the restriction of the coils inside the box. You should determine the operating pressure of your homemade jockey box empirically. Fill an empty keg with water and apply a test pressure. Start low, say 10 or 15 psi. Time how long it takes to fill a 12-oz glass - aim for 6 seconds. That translates into a flow rate of 1 gal/min, which is optimum for dispensing draft beer. If your first test pull is too slow, kick up the pressure and retest until you reach your 1 gal/min flow rate.

Another suggestion related to pressure: Remember that a jockey box is not a substitute for a refrigerator. It is designed only for dispensing a lot of beer in a short time. In this usage, high dispense pressure is all right. If you have beer left over in your keg after the picnic or party, however, you must lower the head pressure in the keg to a more normal level (10-12 psi) afterward. Otherwise the beer will absorb too much gas from the headspace and become overcarbonated.

Finally, Teri's suggestion of cleaning the jockey box coils with trisodium phosphate (TSP) using carbon dioxide pressure is good, but ideally you should use a small pump so that you can backflush the coils in a recirculation arrangement using a bucket as a reservoir. Be sure to include your beer lines in the recirculation loop. First flush out the coils with tap water, then start pumping the cleaning solution. 10 min per coil is usually sufficient.

I use a commercial beer line cleaner (which your homebrew supplier can get for you from several sources, including Foxx equipment in Kansas City and Johnson Enterprises in Wisconsin). For unfiltered beers, a heavy-duty cleaner containing caustic potash is probably the best bet, but be careful and always wear rubber gloves and eye protection when handling this stuff. After cleaning all the coils, rinse thoroughly with tap water. I prefer to finish up with a recirculation of iodophor, which can be left in the coils until the box is used again. As Teri points out, chlorine must not be left in the coils - it will corrode them. With iodophor, all I have to do is flush out the coils briefly before putting the jockey box into service again.

You should seriously consider Teri's recommendation of stainless rather than copper for the coils. Although copper has better heat transfer characteristics and is cheaper, it is not an ideal material for finished beer.

COLD LIQUOR TANKS FOR COMMERCIAL-SCALE WORT CHILLING

DM: The cold liquor tank is much like a vertical beer tank in that it has a cooling jacket welded to its wall. However, it is an open tank - you probably noticed the hatch-type door on the dome - and it is not designed to take pressure. The tank contains water, and a thermostat on the brewhouse control panel sets the temperature of the water. The only purpose of this cold water is to cool the hot wort when we pump it out of the kettle at the end of whirlpool. The heat exchanger at the brewery works exactly like a counterflow wort cooler, and cold water is the coolant. A dedicated pump pushes the coolant through the heat exchanger.

The reason most brewpubs don't need a cold liquor tank is that they are blessed with a domestic water supply that is cold enough to be used for wort cooling year round. In St. Louis, the tap water runs 80-82 °F (27-28 °C) during the summer months, which obviously won't do if you need to cool your wort to normal pitching temperatures. The cold liquor tank is one way around this problem.

Another solution, which we considered but did not choose, is to use straight tap water to cool the wort as far as possible (practically speaking, down to 87-85 °F [31-29 °C] using 80 °F [27 °C] water), then add a second stage to the heat exchanger and use chilled glycol from the refrigeration unit to finish the job. The problem with this approach is that it requires a big refrigeration unit to keep up with even a modest wort cooling demand, such as dropping 15 bbl of wort from 85 to 70 °F (29 to 21 °C) during the course of a 40-min knockout. When we did all the calculations, we found it was cheaper to get a cold liquor tank than to get a vastly bigger refrigeration unit that would be stretched to its capacity only a couple of hours a week.

Another way to look at it is that the cold liquor tank spreads the load of cooling the hot wort. With or without a cold liquor tank, the glycol refrigeration unit is what does the cooling, but with a cold liquor tank, the unit can take 24 h, if need be, to get the water down to temperature (34 °F [1 °C]); then the water can deliver that cooling power to the heat exchanger in less than 1 h. Using a cold liquor tank allowed us to get by with a much smaller refrigeration unit, and that proved to be the most economical way to get the job done.

Yes, I have flown south. What can I say? The folks down here made me an offer I couldn't refuse. After having tasted the beer in the Tap Room, I'm sure you'll agree that I left the it in capable hands.

REFERENCE