Dear Mr. Atherns,
I must express my deep personal appreciation of you and others taking the time to comment on such an important issue. My experience with Grand Canyon Railway and our water treatment program has drawn some interesting pictures. We treat our water from one softener. The daily maintenance can be monitored to limit irregularities in the program. To satisfy our water needs at the canyon, we transport softened water to the canyon in water cars. Our experience tells us that this softened water will become dirty from just sitting in the tank cars and we need to carefully rotate our supply. 4960 has a continuous blowdown and we can control its operation in the cab. We have found that this has its effective limits. If water stagnates for a few days, it can develop enough impurities to cause the conductivity of the water to rise even with the use of the continuous blowdown. We have also found that an aggressive program of regular blowdown practices can keep 4960’s boiler quite clean no matter the water’s age.
The issue of stressing the boiler goes beyond the fireup shut down. As you stated the boiler sheets do not do well with cold water hitting a hot sheet. They also do not do well when being subjected to stresses at low temperatures. The failure modes of boiler steel changes near the 70 F range. The steels being at temperatures below this range can cause a failure for particular material characteristics not necessarily seen in normal operation. Again thank you for your thoughts.
Sincerely,
Robby Peartree