With air conditioning becoming more of an accepted “extra,” companies are looking at how to keep costs down, including those to the environment
didn’t justify it in most cases,” said Lehnert. Many safety-, reliability- and performance-related features
have made their way from the motorcoach and transit bus in- dustries to the yellow bus, according to Matt Lish, the North American director of transport sales at Bitzer US, Inc. Sometimes these are accomplished by following in the steps of one state. “Different state and local authorities are learning more and
more about what the proper school bus A/C system should in- clude,” said Lish. “Florida is a great example.” Florida was one of the first states to specify suction accumula-
tors in all systems and “transit style” compressors, which greatly improve the long term reliability of the systems. Te introduction of free-blow air distribution as an alternative
to ducted air distribution also cut costs. Without the labor and parts related to the air distribution ducts, the cost of the system came down. While ducted air distribution works better for lon- ger bus rides, the short rides that most students are used to make the solution much more cost-effective.
Replacing the Refrigerant Most people remember the beginnings of a campaign to re-
verse the effects of anti-chlorofluorocarbons (CFCs) that started with changing how aerosol cans projected their contents. Te movement also caused the air conditioning industry to move away from using R-12, a CFC refrigerant, in 1995 to using R134a, a hydrofluorocarbon refrigerant that is non-ozone-depleting. Ac- cording to some industry reps, R134a is less stable over time and does not have the 100-year life span of R12, greatly reducing the effect on the ozone layer. “Tis change over was mandated and implemented before the
industry was ready, which caused customers and manufactur- ers a lot of pain,” said Lehnert, explaining that R134a is a smaller molecule and would leak through the hoses, fittings and seals that were being utilized. Manufacturers also had to change from using a mineral-based lubricant with R-12 to polyalkylene glycol, or PAG, lubricants. “A lot of expensive lessons and pain for cus- tomers during that hasty conversion.”
www.stnonline.com 37
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56