Resource Library

A drawing specifies TUNGUM for a pipe. What is TUNGUM?

TUNGUM is a trade name for aluminium-nickel-silicon-brass. CW700R (CZ127).
Are small diameter tubes necessary for increasing the energy efficiency of air conditioners?

No. The system energy efficiency can also be achieved with conventional tubes (such as 3/8 inch diameter tubes) simply by using more tubes and thereby increasing the surface area available for heat transfer. Nevertheless, a penalty is paid in terms of the increased weight of tube material and fin material as well as increased refrigerant volume. In general, if larger diameter tubes are used then a larger coil size is necessary to achieve the same performance and energy efficiency that could be achieved in a more compact system with smaller diameter tubes.
Are the 1, 2 and 5 Cent Euro coins pure copper?

No, they are made from steel coated with a thin layer of copper.
Are weld repairs permissible on Class1 and Class 2 Forgings produced to Def Stan 02-879 Part 2?

The rectification of defects by welding is not permitted on Class 1 and Class 2 forgings.
Can leaded solders be used on drinking water installations?

No.
Are weld repairs permissible on Class1 and Class 2 Forgings produced to Def Stan 02-879 Part 2?

The rectification of defects by welding is not permitted on Class 1 and Class 2 forgings.
Are small diameter tubes necessary for increasing the energy efficiency of air conditioners?

No. The system energy efficiency can also be achieved with conventional tubes (such as 3/8 inch diameter tubes) simply by using more tubes and thereby increasing the surface area available for heat transfer. Nevertheless, a penalty is paid in terms of the increased weight of tube material and fin material as well as increased refrigerant volume. In general, if larger diameter tubes are used then a larger coil size is necessary to achieve the same performance and energy efficiency that could be achieved in a more compact system with smaller diameter tubes.
Are the 1, 2 and 5 Cent Euro coins pure copper?

No, they are made from steel coated with a thin layer of copper.
Are hygienic copper surfaces coated?

No, the hygienic property of copper is intrinsic to the metal.  In order to maintain this benefit, oils, waxes, glosses, paints and other coatings must NOT be applied.
An engineering report suggests that Stress Corrosion Cracking (SCC) is a problem in brass tubes. What steps may be taken to avoid SCC?

SCC occurs due to the combined effect of stress and corrosion. The stress may be removed by a stress relief anneal at 250 to 300° C for ½ to 1 hour.
Can chrome plated copper tube be formed into a bend?

Yes, with care and the correct procedure.
Are 90-10 and 70-30 copper-nickels susceptible to stress corrosion cracking?

They do not experience chloride or sulphide stress corrosion. They have a high resistance to ammonia stress corrosion compared to other copper alloys and do not require a stress relief anneal for seawater service.