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Old 05-11-2009, 10:12 AM
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Lu47Dan Lu47Dan is offline
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Join Date: Mar 2006
Location: N/W Pa.
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Default Copper tubing , fittings and fitting terminology

Copper Tubing & Fitting Terminology :
Copper tubing is measured by internal or "nominal" dimension , in other words a 1/2" copper tube measures 5/8" on the outside diameter .
  • Nominal - Actual
  • 1/2" - - - - -5/8"
  • 3/4"- - - - - 7/8"
  • 1"- - - - - - 1-1/8"
Copper tubing that is generally available ranges in size from 1/8" to 2" . It is available up to 8". DWV tubing and fittings should not be used in a pressurized system as SOP . DWV is short for Drain , Waste , Vent .
There are several types and grades of copper tubing available on the market today
Types include stick copper and coiled copper ;
Stick copper can be purchased in two hardness's , as drawn or drawn (hard) and annealed ( soft ) , drawn copper is usually what you find at hardware , home and plumbing supply stores in the stick form . In this thread , drawn stick is what we will be discussing .
Coiled copper at the hardware , home and plumbing supply store will most likely be annealed , annealed copper is soft and bends fairly easily and is mainly used for installations that require no joints when it is installed . One example of this would be a water line from the house to the water main , another would be a water line under the concrete floor of your garage , no joints equals no leaks (in theory) . Exposed piping can be done with coiled but hard drawn stick tubing ends up looking nicer than coiled does .
Grades of copper include K , L , M, DWV, ACR , And the Medical Gas Grades . We will concern ourselves with K , L , and M
K - copper is the heaviest of these three grades .
L - copper is the standard weight
M - copper is the lightest weight copper
Each grade of copper has an identifying color code for it .
K - Green lettering and stripe .
L - Blue lettering and stripe .
M - Red lettering and stripe .
When using copper tubing for air lines K would be the best choice , but L will work fine .
Fitting Terminology
Copper fittings come in two types , water and drainage , and in wrought and cast copper , and copper alloy pressure fittings .
If the copper fitting is designed for drainage do not use it in a pressurized system .
Fitting ends are classified as copper or fitting ;
Copper (C) the bell of the fitting slips over the outside diameter of the tubing .
Fitting (F) will insert into the bell of a standard C X C fitting
The best example of this is a street elbow (image 1) .
All copper fittings are designated this way
Couplings & Related Fittings
Couplers are the simplest fitting in use today , there are two types straight (my term) and reducing couplings ,
Straight couplings join two tubes of the same type , but are available with or without stops . Stops do what it sounds like , they stop the insertion of the tube at a set point in the fitting .
A coupling without stops is used when a repair or addition of a fitting is required , it can be slid back onto the tubing to allow for easier installation of the repair piece or fitting then slid over the joint . Care must be exercised when doing this to insure that the tubing ends are cover by the coupling equally . This usually means marking one or both tube ends before the coupling is slid in place .
Couplings are C X C ------ 1/2" X 1/2" (image 2)
Reducing Couplings do just that reduce from one pipe size to a smaller on in a straight line .
They are C X C ----------3/4" X 1/2" (image 3)
Bushing reduce the size of a fitting , there are two types .
Bushing and Flush bushings .
Bushings use a fitting end to fit into the bell of another fitting to reduce its size without a piece of tubing between them . This eliminates one joint that would need solder and one possible leak point . (image 4)
Flush bushings are inserted into a bell of a fitting to do the same thing as a regular bushing but end up flush to the end of the bell . (image 5)
More tomorrow. Dan
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Last edited by Lu47Dan; 05-17-2009 at 11:28 AM. Reason: To hilite the coupling section
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