Basic Concepts of PlumbingThere are no difficult concepts in plumbingSewage dont run uphill and payday is FridayThere can be some complicated implementations, particularly in vacuum systems, particularly if you let physicists design them!

NPT: National Pipe ThreadBlack and galvanized pipe: dimensions and fittings. Galvanized pipe is zinc-plated and used for water and compressed air, which often contains considerable quantities of waterBlack pipe is used for gas (Natural gas), it rusts easily when wet.Pipe is typically rigid; it doesnt bend easily

Pipe TerminologyPipe is measured on the ID (inside diameter), approximately.Actually its measured on the OD (outside diameter), but that number makes no sense! (See below) The naming standard used to be IPS (Iron Pipe Size), but has been supplanted by NPS (Nominal Pipe Size). Schedule refers to the wall thicknessSchedule 40" is the normal/common thicknessAll schedules of the same nominal size must have the same OD to be compatible with the same size fittingsIn Europe, pressure piping uses the same pipe IDs and wall thicknesses as Nominal Pipe Size, but labels them with a metric Diameter Nominal (DN) instead of the imperial NPS. (Wikipedia: pope (material))

Pipe Varieties and MetricConversions

Pipe Terminology" schedule 40 pipe has an OD of 0.840", thickness of 0.109" and ID of 0.622 schedule 80 has a wall of 0.147" and ID of 0.546", schedule 160 has a wall of 0.187" and ID of 0.466". Remember that all schedules of the same nominal size must have the same OD to be compatible with the same size fittings Is that all perfectly clear and is it now obvious why its called " pipe? (You recognize sarcasm, yes?)Other sizes of pipe dont make any more sense than this. Plastic sprinkler pipe also comes in schedules; the pipe is typically schedule 40 but fittings are typically schedule 80.

Noel Denevers, Fluid Mechanics, Addison-Wesley, Reading MA, p. 471-474 (1970)

Nomenclature of Pipe FittingsFittinga joint or connector, as an elbow, union, or tee, used in a pipe system. (Dictionary.com)Couplings: require significant motion of pipes, particularly along the axis of the pipe. Typically used during installation of a plumbing system. Unions: Require minimal longitudinal motion of the pipe. Typically used to install and exchange appliances after plumbing system has been constructed.Bushings: used to change pipe size.TeesElbows: 90 and 45Street fittings are asexualNipple: a short piece of pipe, threaded on both ends, used to connect two fittings.

Pipe FittingsIron pipe fittings have a tapered threadTypically sealed with Teflon tape. The taper half-angle is 1 47', which corresponds to 3/4" decrease in diameter per foot of thread.Demo of threaded pipe joint. How tight do you make it? Tight enough that it doesnt leak!

TubingTubing is measured on the OD and is exact...well sort of. An alleged piece of 1" x 1/8" wall stainless tubing was measured to be 1.050". As usual, caveat emptor!Tubing available in many materialsCopperFlexible: used extensively refrigeration, water and many other applicationsRigid (aka pipe, but measured on OD!): used extensively for water, especially in homesBrass StainlessHigh quality vacuum systems often made with welded stainless tubingAll sorts of exotic metals (including platinum!)

Pipe and TubingPipe is rigid: Changes in direction are made with elbows and teesTubing can be bentCopper tubing can be easily bent by handBenders available for other metalsElectrical Metallic Tubing (EMT)Used extensively for commercial wiringEMT benders are commonReplacement car exhaust systems are now custom-made for each model in each installation

Pipe and TubingTube fittings typically slip togetherPlastic pipe fittings are made permanent with glueMetal fittings are made permanent with solder (sweated) or welding (stainless)

SolderingTypes of solderSoftLead/tin alloysDifferent alloys have different melting points and strengthsApply with iron or propane torchSolid core is typically used for plumbingRosin core is used (without flux) for electrical connectionsSilverMuch stronger and higher melting than lead/tin soldersApply with oxy-acetylene torchMany specialty typed for special applicationsTypes of fluxGreen Streak contains acid and is very corrosive to electronics but fine for copper pipeSuperior 90 is great for electronics and adequate for copper pipe

Swagelok: Plumbing for PhysicistsFittings, nuts and ferrules. Demo: the Swagelok catalogStandard Swagelok is not appropriate for applications that need to be changed often. Definitely ditto for tapered pipe fittings.

Swagelok: Plumbing for PhysicistsUltraTorr compression O-ring fittings. Excellent for repeated changes; should last forever with occasional change of O-ringsGreat for vacuumWill not tolerate high pressure!VCO fittingsO-ring fittings that can be changed repeatedlyWill tolerate moderate pressuresVCR fittings:Typically used on welded stainless steel systems for extremely high vacuum or where leaks absolutely cannot be tolerated like silane and arsine lines. Like mini-conflat fittings: they come with a gasket that is single-use. Intended as removable fittings in bakeable, welded all-metal systems. It makes no sense to put Teflon tape on a Swagelok or conflat fitting. (Ditto for the joint between a regulator and gas cylinder.)

Plumbing with GlassGlass comes in numerous gradesFused silica is high purity SiO2 typically about 99.99% pureUsable to 1200 CVery low coefficient of thermal expansionCan be thrust into water for 1500 C!Vycor is a trade name for 96% pure silicaPyrex Approximately 81% SiO2, 2% Al2O3, 4% Na2O, 0.5% K2O and 13% B2O3Very common for labwareLow coefficient of thermal expansionUsable in flames and on hotplatesFlint glass is commonly used for lenses

Plumbing with GlassGround joints and ball joints: nomenclature and sizesGround joints are classified by a standard taper size 24/40 is quite common for intermediate-sized jointsThe maximum diameter of the taper is 24 mmThe taper is 40 mm longGround glass fitting is typically sealed with vacuum greaseGrease can be removed with piranha solutionFrozen joints can be loosened by Coca Cola!Stopcocks are sized by the diameter of the hole (mm)Connections made by welding in a flame: glassblowing

Plumbing with GlassAce and Fisher PorterGrease-free couplings and connectorsGrease is a place for volatile contaminants to adsorb and outgas foreverGreased fittings cannot be bakedGas handling systems in OEML are completely grease-freeGlass, Teflon and metal parts onlySuitable for use with reactive gasesSwagelok can be connected to glass by using teflon or nylon ferrulesAce also has fittings that directly connect to Swagelok