Best (Easiest) method to check dissolved oxygen levels in make up water.

A special section just for steam engines and boilers, as without these you may as well fit a sail.
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Best (Easiest) method to check dissolved oxygen levels in make up water.

Post by Mfoxchicago » Tue Jun 18, 2019 4:24 am

Hey Captains, What is your recommended method, preferably an easy method, to check the dissolved oxygen levels in my hotwell feed water. Recently replaced a couple of water tube boiler pipes that finally succumbed to age. I do treat my feed water, use rain water year round, but was advised to check my makeup water's oxygen levels.

Your thoughts......

Thanks. - Capt. Mack
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Lake Nasworthy, San Angelo, Texas

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Re: Best (Easiest) method to check dissolved oxygen levels in make up water.

Post by barts » Tue Jun 18, 2019 1:43 pm

Hi Captain Mack -

I've never seen anyone do this on our small steamboat boilers, but you've got one larger than most and it's used more than most. I'd probably go with an meter, but there are regents as well that one can use to do a visual color comparison, as well as a traditional titration procedure. As one would expect you can get such a meter from Amazon.

Proper boiler water treatment for a large boiler contains an oxygen-getter. Maintaining proper hot well temperatures (too hot to touch - 150F or so) will help reduce dissolved gasses to a minimum. If you're not running condensing, then your boiler feed water will probably have a fair amount of oxygen, esp. if fish can survive in it :).

- Bart
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Re: Best (Easiest) method to check dissolved oxygen levels in make up water.

Post by Oilking » Tue Jun 18, 2019 10:40 pm

Capt. Mack
The easiest way is to not measure the DO at all?!
On the ST Portland we are using AGK100 a Drew Marine product that contains Hydrazine and a corrosion inhibitor, also sold as separate compounds under the name Drewplex. We use two test kits one for hydrazine and one for hydrate alkalinity. A conductivity meter is used to track dissolved solids. As long as the hydrazine remains above 0.03ppm there should be no DO present. The Portland is a floating locomotive so all the feed water goes up the stack. O condensing sytems the hydrazine will volatilize and find it's way into the return condensate. I am looking at changing to the Drewplex system since early in the season we have trouble getting the alkalinity high enough without way over shooting and wasting hydrazine. As a way to reduce corrosion in our uncoated feed tanks we are adding sodium sulfite (not sulfate) as we fill the tanks. The dosage is based on the average DO of the city water which works out to about 1.6lb/1000gal.

David Vik
ST Portland
Oregon Maritime Museum
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