Coal Plant SO2 effects on handtools

[Patrick Chase]

SO2 is also used as a preservative in some food, check a package of dried pineapple, and at one time many years ago it was used as a refrigerant in early refrigerators until a safer better smelling chemical was developed.

Of course that safer better-smelling chemical (Freon) turned out to have eaten a hole in the Ozone layer, and was banned. We're on plan C now (or D if you also count the interim use of HCFCs between Freon and the current HFCs)

[Dave Beauchesne]

I have been a HVAC guy for 38 years now ( EEEEK!! )

I have been at a Pulp / Paper Mill for the past 15 - there are trace amounts of H2S and SO2 most everywhere and some buildings a bit more than others, even when there are no excursions / leaks.

What I see is as follows: Copper and brass turn black in some of the worst buildings, sometimes within weeks. Most of the Mill site - copper and brass oxidize - to varying degrees of black - at higher rates than ' outside ' the Mill site. I see little to no green oxidation, just blackening of the copper or brass ( and HVAC equipment has a fair amount of both.

Dissimilar metal contact points take a kicking in the atmosphere as well.

One of the worst places for attack ( a bit off topic but interesting none the less ) is the braze compound universally used in HVAC systems that is a copper ( 80 + % ) silver ( 15% ) and a bit of phosphorous ( as a fluxing agent ) - one trade name is Silfos. It is used because it is self fluxing on copper, melts in the 1300 F range and has great gap filling capabilities - very easy to use, and will take 600 PSI +++ no problem.

The one issue at Pulp Mills ( and at rubber tire manufacturing plants so I am told ) is that the trace amounts of sulfur in the atmosphere attack the phosphorous and essentially turn it into Swiss Cheese and leaks occur - sometimes quite bad quite quickly, sometimes enough to weep the lubricant that is continually circulating in the system, but not leak any refrigerant.

Silver solder ( actually a brazing range product ) that has 45% silver and melts closer to 1200 F has no leakage problems from the sulfur floating around ( due to no phosphorous ) but is not used as much as joint cleanliness and an added fluxing agent are required.

Soft silver bearing solder ( in the 500 F range ) works well as well, but the high pressures of the newer refrigerants are a strain and joint failure is common.

Sorry to cause a snooze fest, but I have a couple LN block planes in yellow and white bronze at home that are great and cause me no grief.

Good luck.

Dave B