boiler PH

ChrisJ

I tested the PH of my tap water and came up with 7. The test paper I'm using goes from 1 to 13 so its 1 step increments. I tested water out of the boiler and my best guess is it is between 6 and 7 but certainly lighter than the direct tap water.



My understanding is its prefered to be more alkaline than acidic so if anything I would want to be closer to 8 or 9?

I will be using Rectorseal Steamaster tablets starting tonight so I have no idea what this will do to the PH? I seem to recall people saying water treatments often raise the PH but maybe I'm remembering wrong.  I'm wondering if I should pickup some baking soda just in case and if I do just how high do I want the PH to be?

Hap_Hazzard

Yours is too low.

I remember hearing two different numbers with respect to aqueous oxidation of steel. I wish I could remember what the reasoning was, and I'm also not sure how this relates to cast iron (which is basically extra-high carbon steel). What I'm clear on is that, at pH < 9.5, oxygen will attack steel causing surface pitting, but then I remember reading somewhere that a pH of 11–11.5 was recommended to minimize oxidation.



I have always kept mine at around 9.5 pH, which is relatively easy to do since my tap water is pretty basic and also high alkalinity. Even though it undergoes some drastic changes when it's heated, with a substantial portion of the mineral salts precipitating, it still ends up with pH > 9. Then if I skim with washing soda (aka sodium carbonate or soda ash) it tends to end up a little higher because I never rinse out all of the soda.



I would recommend you stick with washing soda rather than baking soda (sodium bicarbonate) to adjust your pH. If for no other reason, I simply haven't seen what baking soda does inside a boiler, but I know a lot of people smarter than I am who are totally comfortable using washing soda.



Whatever you decide to use, it's always a good idea to try some in a pan on your stove before you put it in your boiler. (I wish I could remember who suggested this, but it's not my idea.) Wait until your wife isn't home, take a little water out of your boiler--you only need a couple of inches in the bottom of the pan--and put it in a pan on the stove. Then add a little of whatever you were contemplating adding to your boiler water and bring it to a boil. If a column of foam rises out of the pan, or if it makes the steam bubbles bigger than normal or it bumps instead of rolling, you might want to reconsider putting it in your boiler.

Rod

Boiler PH

Hi Chris- This article of Dan's may be of help to you.

http://www.heatinghelp.com/article/183/Plumbing-Mechanical-articles/2522/The-Power-of-Hydrogen-February-2012

Hap_Hazzard

Litmus paper?

Litmus paper only works from pH 4.5–8.3, and if it gets old it doesn't work at all. Universal Indicator paper works across the whole spectrum (1–14), but it's also perishable and only as accurate as your interpretation and the comparator. The comparators in most paper kits are not very accurate to begin with, and they fade and change color over time.



Liquid kits tend to be better, but any colorimetric system involves interpretation and can be thrown off by rust and other contaminants.



The only really accurate way to measure pH with an indicator is by titration with a reference solution until the indicator, like phenolphthalein or thymolphthalein, turns colorless. This is not as hard to do as it sounds, and it would be easy to make a kit for field use that would be cheap, accurate and easy to use. I'm sure somebody would be selling these today if it weren't for the fact that you can buy digital pH meters you can stick in your pocket for less than $20.



Litmus paper, schmitmus paper. And I still say 9.5 is the best pH for boiler water.