If a calculator like Bru'n Water says I need to a liquid substance like acid, what's the best technique for measuring out and dispensing the liquid, especially in fractional small amounts (eg 1.3 ml)?
Measuring and dispensing liquids like acid
- Thread starter auburntsts
- Start date
Help Support Homebrew Talk - Beer, Wine, Mead, & Cider Brewing Discussion Forum:
Silver_Is_Money
Larry Sayre, Developer of 'Mash Made Easy'
I use a range of plastic syringes that are scaled in mL, and that cover a wide selection of mL volumes.
Foosier
Well-Known Member
Medicine syringes given for free with kids antibiotics are great for very small amounts and measure in milliliters.
mashinary
Well-Known Member
This is what I do too.
triethylborane
Well-Known Member
The best? A pipetting robot. But the graduated plastic syringes as mentioned above will likely do OK.
OP
OP
High School and College Chemistry classes are a long way in the rearview mirror now. Any issues with the acids commonly used for water adjustment adversely interacting with plastic syringes?
OP
OP
Yeah in hindsight I probably used the wrong choice of words. "Most practical" would be a better term. Cheap but effective would be another.
triethylborane
Well-Known Member
Depends on the acid and the plastic.
Here is a reference to check:
http://www.plasticsintl.com/plastics_chemical_resistence_chart.html
Silver_Is_Money
Larry Sayre, Developer of 'Mash Made Easy'
Well, for one rather extreme example, hydrofluoric acid will etch glass (and given long enough contact time will dissolve it), but it doesn't hurt plastic.
triethylborane
Well-Known Member
Lol, just me being a pedantic *******.
kozer99
Member
kozer99
Member
A glass pipette from Amazon is what I use.
Cavpilot2000
Well-Known Member
If you have a friend who is a nurse or doctor (my fiancee is a nurse), ask them for some syringes. Mine got me syringes ranging from 1 ml (for very fine fractional work, like your 0.3 ml) to 20 ml (I have 1, 3, 5, 10, and 20 ml syringes). They're free, they won't break on you like a pipette will, and they won't react with the common brewing acids, at least not in the timeframe they will be exposed.
I probably do most dispensations of acid with Hach TenSette pipets. One is adjustable from .1 to 1 mL and the other from 1 - 10 ml. For quantities less than that I use an Eppendorf adjustable pipetter. These all use disposable tips but they are very handy.
I got some plastic disposable pipettes from Amazon. Use one per brew to dispense lactic acid, give it a toss when over (yes I feel guilty).
triethylborane
Well-Known Member
Nice equipment, clearly you have lab experience (from the brulosophy thread prob BS Chem? or ChE?)
BSEng., MSEng. both electrical.
Lactic acid comes in a plastic bottle. If it lactic acid did anything to plastic, there would be a lot of empty bottles with lactic acid dripping out.
I either use the little mL cups that come with cough syrup (for when I need to measure 1/2oz or oz) or the baby syringes from a pharmacy. I got one free at Walmart. Rinse and reuse.
I either use the little mL cups that come with cough syrup (for when I need to measure 1/2oz or oz) or the baby syringes from a pharmacy. I got one free at Walmart. Rinse and reuse.
Pipettes of the correct volume are the most accurate, but probably overkill for beer brewing. Correctly sized syringes are close enough, at least IMO.
If you always end up adding really small acid amounts, pre-dilute those acids to a more useful strength, so slight measuring errors are more forgiving. Narrower measuring vessels are more accurate than wider ones. For that reason I would avoid using cough syrup cups. The indications are also highly inaccurate, unless you recalibrate them using a precision scale.
For really small additions, one could also count drops...
If you always end up adding really small acid amounts, pre-dilute those acids to a more useful strength, so slight measuring errors are more forgiving. Narrower measuring vessels are more accurate than wider ones. For that reason I would avoid using cough syrup cups. The indications are also highly inaccurate, unless you recalibrate them using a precision scale.
For really small additions, one could also count drops...
OP
OP
I wouldn't necessarily make that assumption. Not all plastics are created equal so just because a given acid was shipped in plastic doesn't mean it won't interact with other types. Looking at a syringe, it would appear to me that it's possible that 3 different plastics could be used in the construction of the major parts (barrel, plunger, and stopper).
Plus my question was more generic as there's a number acids that can be used in brewing and at different strengths. While my concern maybe unwarranted, in my ignorance I figured it was better to play it safe and ask the question rather to risk an unnecessary chemical burn. YMMV.....
kozer99
Member
I use a glass pipette and a pipette pump. They are very accurate since you are dealing with milliliters of acid.
At the request of Bru'n Water users, I'm in the process of adding the ability to report liquid acid amounts in mass terms. Liquid acid amounts are currently reported only in volumetric terms. All solid acids and minerals in Bru'n Water are currently reported in mass terms. This conversion will be no problem since the acid density curves are already in the program. The main issue is in how to clearly report the units to the User.
Since most homebrewers that practice water adjustment, have scales that can report in fractional grams, it can be much more accurate to drop liquid acid into a tared container until the desired mass is attained.
Since most homebrewers that practice water adjustment, have scales that can report in fractional grams, it can be much more accurate to drop liquid acid into a tared container until the desired mass is attained.
Silver_Is_Money
Larry Sayre, Developer of 'Mash Made Easy'
I use a gaggle of plastic syringes of varying capacities.
If you are doing weight you are no longer concerned about density. A gram of 88% lactic acid solution contains 0.88 gram lactic acid. As the molecular weight of lactic acid is 90.08 this is 880/90.08 = 9.769 mmol per gram of solution. Now all you need to know is that a mmol of lactic acid produces 0.973 mEq of protons at pH 5.4 and 0.983 at 5.6 and there you are.
FunkedOut
FunkedOver
- Joined
- Mar 23, 2017
- Messages
- 849
- Reaction score
- 417
@ajdelange it's been too long since i've practiced any of the chemistry i learned to get through school.
how does that information help me know the weight of 1.3ml of 88% lactic acid?
OP states he's using a spreadsheet (Bru'n Water) that asks him to measure 1.3ml of an acid.
Is density not quantity of mass per unit volume?
I think the information you provided is the key to unlock bypassing the volumetric measurement all together.
Yes?
how does that information help me know the weight of 1.3ml of 88% lactic acid?
OP states he's using a spreadsheet (Bru'n Water) that asks him to measure 1.3ml of an acid.
Is density not quantity of mass per unit volume?
I think the information you provided is the key to unlock bypassing the volumetric measurement all together.
Yes?
This was just another charge in my Quixotic campaign to try to get people to appreciate how much easier their lives would be (or the brewing calculation parts of them at any rate) if they quantified acid and bases in their natural units: mEq.
