The science of plumbing
A cooperative effort has helped to thwart a non-compatibility issue and for that, University of Lethbridge students, staff and faculty can be thankful this winter.
When the Central Plant’s hot water heating system began to see a number of its valves fail, their rubber linings chewed away to the point where they no longer held water, TJ Hanson and his Utilities staff suspected something more sinister than wear and tear was at the heart of the problem.
“The last few years we’ve had a number of incidents where valves throughout the system just weren’t holding,” says Hanson, the director of Facility Operations and Maintencance. “We would close a valve but water would continue through the line and it made it very difficult to isolate a boiler for service.”
A total of three gas fired boilers work in unison to supply closed loop hot water heating to the U of L. With valves continuing to fail and another winter heating season looming, Hanson and the Utilities crew knew something had to be done.
“When we opened the valves up and looked at them they were all deteriorating or completely chewed up,” says Hanson. “We had a chemical analysis done of the water in the system and we spoke with the valve supplier, but they assured us their valves were fine.”
So, the crew decided to seek out its own expert – and found him in-house.
“Terry Sutton came up with the idea that we should contact someone in our chemistry department,” says Hanson.
The chemistry someone in question was Dr. René Boeré, and it didn’t take long for Boeré to determine what was wrong with the University’s failing valves. By examining the 20 or so constituents in the boiler water, their concentration and subsequently checking their compatibility with the rubber material (known as EPDM) of the valves, Boeré found a problem.
“The list from the analyst contained a range of substances, which I compared to a chemical compatibility index,” says Boeré. “EPDM is supposed to have good compatibility with the majority of the ingredients in the boiler water. Of those species present that might attack this rubber, I looked at how much was identified as being in the water. Of these, the substance morpholine was one of the highest in concentration and most deleterious to EPDM.”
Morpholine is an antiquated agent that has been used in steam and hot water systems because it distributes evenly between hot water and steam, and provides corrosion protection. Chemicals of its type have not been used in the University’s systems for well over 25 years. However, it has remained present as a legacy chemical and in ever-declining concentration.
“That was, more or less, our smoking gun,” says Hanson, who now had a summer project on his hands.
The only solution was to shut down the entire system, clean it out and start from scratch.
“We drained and refilled the entire system twice, and circulated the water each time to flush it out,” says Hanson. “Then we began the process of replacing valves on campus, a total of 220, ranging in size from four to 14 inches.”
The system is now free of Morpholine and with the heating season on the doorstep, the University is prepared, all thanks to the cooperative work of two very distinct University units.
“We have to think all the time about the kinds of materials we use to handle a wide range of chemicals, thus we get used to the idea of checking material compatibility,” says Boeré. “It was a pleasure to be able to use these skills to help out TJ and his staff as they work to keep us warm throughout the winter. I think it’s easy for us in the offices and classrooms to take their work for granted.”
For a look at the full issue of the November Legend in a flipbook format, follow this link.