steam boiler alkalinity reading?

[Deleted User]

minimum and maximum alkalinity reading be?
is it something that really should be checked for?

John@Reliable

Ph levels

Most manufacturers of Hydronic and a/c equipment recommend a ph valve of 7.5 to 8.5 in circulating water. Excessive acidity ( ph 5-6 ) causes corrosion and high alkalinity (ph 8-10) will cause heavy scale deposits on hot heat transfer surfaces. As far as checking can't hurt,but chemical treatment for small house units other than your own is not needed I say.Hope this helps!

canuckDale

Ya But...

pH and alkalinity are related, but not really linearily.

Alkalinity is the measure of bicarbonates, carbonates and hydroxyl ions.

pH measures free or potential hydrogen.

pH 8.2 can have HIGH alkalinty- 2000ppm. But it exists as bicarbonate.

pH 8.4 can have HIGH alkalinity- 2000ppm. But it exists as carbonate, with no or little bicarbonate because the free hydrogen has combined with the 'H' of the bicarbonate and formed water.

pH 11.5 can have high alkalinity- 2000ppm. But it exists as hydroxyl alkalinity.

In HWH you strive for 8.5-9.5pH and an alk of about 50-100 because that is the level at which steel corrodes least and scaling is minimal.

In steam systems you strive for 10.5-11.5 pH and an alkalinity of 100-200ppm. You need this hydroxl alk to turn those bi-carbs to carbs and not scale your boiler while protecting low corrosion rates. And you need the hydroxyl and pH to precipitate Ca and Mg hardness so it can be blown down and not accumulate on the heating surfaces.

You test with Methylethel (M) and Phenolthaline (P). M tests the bicarbs 5.5ph-8.3 pH, P tests the carbs 8.3 pH-10.5pH . To find the hydroxyl, the equation is 2P - M = OH-.

I need a hobby! ;-)

pH and Alk are not one in the same.

I should have not skipped those Chem classes!

Hope this helps. Hell! It still confuses me!

Dale

canuckDale

Sorry Guys

I just understood how to respond to a thread and NOT move it up the wall.

Excuse me. Sorry. Argh!!!!!!

Dale

[Deleted User]

wow

i think you answered my question tho....i knew about the ph levels but was curious about the ppm of the alkalinity,...it was a swimming pool test that awoke my curiosity...i figured there had to be some sort of perameter for it tho, cause they sell chemicals to alter the alkalinity as well as seperate ones for ph altering...thanks,,it was a bit over my head but the ppm measurements will help..