testing ph level

zepfan

when testing a boiler'sph level is it better to use litmus paper, or  a ph tester? if a tester is better does anyone know of an economial model,and where you can get one   

Hap_Hazzard

pH testing

I don't think you're really going to find litmus paper around these days. There are some paper-based universal indicators, but I don't consider them worth the money.



When I took chemistry, pH meters were very expensive. I learned how to measure pH by titration with an indicator that has a definite extinction point, like phenolphthalein or thymolphthalein, because it's easier to tell when a solution becomes colorless than it is to match the shade of bluish green to a comparator. By measuring how much of a known acid or base reference solution is required to titrate an unknown solution to the extinction point, the pH of the unknown can be estimated to the limit of the volumetric apparatus being used. This kind of measurement was used to calibrate those expensive pH meters, and it's still the gold standard.



It wouldn't be too hard to design a field kit based on dropwise tiration, but these days there are a variety of testers on the market, ranging in price from less than $20 to hundreds of dollars. Along with varying degrees of sensitivity and durability, some feature temperature measurement and other gimmicks you may or may not need. I think the best approach is just to shop around, read the product information and buyer reviews, and find a unit that offers the features you need at the lowest price you can find from a reputable dealer.



But remember that pH and alkalinity interact in aqueous systems (and so do hardness and temperature), so you need some way of measuring alkalinity too, and you want it to be fairly high. Alkaline water is less corrosive to iron and it also resists pH changes. I don't know of any way to measure alkalinity that doesn't involve titration. You might be able to use a meter instead of an indicator, but the really accurate test uses two or three different indicators so you can measure carbonate, bicarbonate and hydroxide concentrations.

BobC

Litmus paper

I just picked up a vial of 100 litmus paper strips for less than $6 at amazon and the shipping was free as long as your order total was over $25.  http://www.amazon.com/gp/product/B0009K8PPS/ref=oh_details_o04_s00_i02  The range is 1-14 which is very coarse but for boiler water it's probably good enough.



Bob

Hap_Hazzard

That isn't litmus.

Litmus will only work from pH 4.5 to 8.3. It gradually changes from red to blue as pH increases. If your paper has different properties, it is using some other indicator.

BobC

Your probably right

about it not being litmus paper. It shows my tap water is about 5 so i expect the boiler is pretty close to that.



To help get to the free shipping I also picked up a couple spools of OATEY Teflon tape, I measured it and it's about 4 mils thick so I imagine it's similar to the Blue Monster sealant tape.



Bob

Hap_Hazzard

Yow!

Bob, that's way too low! At pH 5 water can literally dissolve iron, and you can pretty much assume there's no scale to protect it. You might want to give those Steamaster tablets a try. They seem to be a pretty safe way to adjust pH and alkalinity to boiler-friendly levels. Just follow Gerry Gills recommendations--he says the manufacturer's instructions have you adding more than necessary.

BobC

Late this week

The tablets will be here by Friday and I will do as Gerry suggests. I'm surprised that water is that low, I guess the acidification of the water shed around the Quabbin is worse than i thought.



Bob

Hap_Hazzard

Quabbin

The Chicopee watershed is very large and fast-moving, so the water doesn't have much time to neutralize its pH or pick up minerals, so you're at the mercy of acid rain.