visible in less than two months in units installed near the ocean. 

 Larger units of central air conditioning systems using copper fins 

 on copper tubes last three to four years depending on exposure. 

 On Guam, the situation is about the same, given similar 

 exposureSo Units run 24 hours per day in both places." 



Of fourteen 3/4-ton air conditioners installed on Guam for a Civil 

 Engineering Laboratory field test in June 1970, six had experienced 

 mechanical failure and were replacedby October 1971. Prior to this 

 experience, the Laboratory had stated: 



"Corrosion of heat exchangers — especially the aluminum fin/copper tube 

 condensers usually supplied in air conditioners—is a continuing 

 expense for replacement or repair. In the warm humid salt air 

 of the tropic islands the problem is especially severe. Aluminum 

 fin/copper tube condensers are destroyed by galvanic corrosion 

 while fins of all copper condensers are destroyed by oxidation. 

 Three to five years is now the expected service life on Guam." 



In less severe environments, it has been observed that rooftop units 

 at the NCBC, Port Hueneme Commissary show extensive coil deterioration 

 and will require replacement after less than ten years' service,, 

 Similar conditions exist at Pt. Mugu. On the other hand, condensing 

 units with tin-dipped, all-copper coils, serving portable, walk-in 

 refer boxes at Pt. Hueneme are still giving satisfactory service after 

 25 years „ 



Problem Magnitude 



The magnitude of corrosion/ fouling problems at Navy shore facilities can 

 be measured by the size of the Navy inventory of air-cooled mechanical 

 refrigeration installations. Such a size estimate was made as part 

 of this investigation in order to assess the potential benefit of a 

 solution. 



Using preliminary results reported in NESO's Air Conditioning Tune-Up 

 (ACTUP) Program equipment survey, combined with data from Pt. Mugu 

 on installed units of all sizes and types, it was estimated that there 

 is somewhat under 300,000 tons of installed capacity in air-cooled 

 refrigeration and air conditioning equipment, Navywide, in sizes as 

 large as 480 tons for a single unit. The estimated breakdown of large 

 and small air-cooled units is as follows: 



Units of 50-ton capacity § over 

 Units under 50-ton capacity 



Tonnage 



Units 



Amount 



Percent 



Number 



Percent 



58,000 



21.4 



590 



4.0 



213,000 



78.6 



14,300 



96o0 



271,000 



100o0 



14,890 



100.0 



42 



