Term

Definition

Air Gap

A device usually mounted at the back of your kitchen sink that connects between your dishwasher and your garbage disposer. It allows your dishwasher to discharge freely to your disposer, yet it prevents contaminated water from siphoning back to your dishes.

Ballcock,

Toilet Threads

A special straight thread size for fittings that connect to Toilets. A Cone Seal or gasket is usually included, because straight threads will not form a complete seal without a gasket of some kind.

Unlike tapered threads, thread sealants should not be used with straight threads, and may actually interfere with proper installation, causing them to leak - or the sealant can act as a lubricant and make it hard to tell if the connection is over tightened. Connections should be firmly and securely tightened against the seal, but care should be taken to avoid over-tightening the joint. For metal fittings, hand tight plus 1/4 to 1/2 turns is usually sufficient. Plastic Wing Nut Fittings are designed to be hand tightened only, without the use of tools.

For example: A 7/8" IPS straight thread fits Toilet connections. Same as 15/16" NPS and 7/8" Slip Joint or 7/8" Ballcock.

See: Straight Pipe Threads

Comp,

Compression

Usually a mechanical copper tube connection. A kind of tubing or pipe connection where a nut, and then a sleeve or ferrule is placed over a copper or plastic tube, and is compressed tightly around the tube as the nut is tightened, forming a positive grip and seal without soldering.

Make sure that you have a good fit and length, and that the tube or pipe is inserted fully into the fitting before you tighten the nut, because once the sleeve is formed, it cannot be removed from the tube. To replace a stop valve of this type, you usually will have to use the existing nut and sleeve unless the pipe extends far enough from the wall to cut it off and install new. It's best to wait until you have to cut the copper pipe, because if it gets too short, you will have to go into the wall to replace it. Thread sealants should not be used on compression joints, and may actually interfere with proper installation, causing them to leak - or the sealant can act as a lubricant and make it hard to tell if the connection is over tightened.

Also applies to flexible connectors that have a nut and gasket designed to attach directly to an SAE standard compression thread, without the use of a sleeve or ferrule.

See: NOM Comp, Nominal Compression

CPVC

Chlorinated Poly Vinyl Chloride Plastic Material.

Like PVC, but withstands higher temperatures.

Usually a decorative metal trim ring that goes around a pipe where it comes out of a wall, to improve the appearance. Installed before stop valve is installed.

Faucet,

Faucet Threads

A special straight thread size for fittings that connect to Faucets. A Cone Seal or gasket is usually included, because straight threads will not form a complete seal without a gasket of some kind.

Unlike tapered threads, thread sealants should not be used with straight threads, and may actually interfere with proper installation, causing them to leak - or the sealant can act as a lubricant and make it hard to tell if the connection is over tightened. Connections should be firmly and securely tightened against the seal, but care should be taken to avoid over-tightening the joint. For metal fittings, hand tight plus 1/4 to 1/2 turns is usually sufficient. Plastic Wing Nut Fittings are designed to be hand tightened only, without the use of tools.

For example: A 1/2" FIP straight thread fits standard 1/2" trade size Faucet Connections (1/2" ID-7/8" OD). Same as 7/8"-14 NPS and 1/2" IPS or 1/2" Slip Joint.

See: Straight Pipe Threads

FIP

Female Iron Pipe Connection.

Flexible

Water Connector

Usually a braided hose that connects your faucet or toilet the water supply stop valve. The same function as a riser, but much more flexible and easier to install. Most often Stainless Steel Braided hose or PVC/Polyester re-enforced hose.

Select a connector of adequate length to avoid sharp bends. Connections should be firmly and securely tightened against the seal, but care should be taken to avoid over-tightening the joint. For metal fittings, hand tight plus 1/4 to 1/2 turns is usually sufficient. Plastic Wing Nut Fittings are designed to be hand tightened only, without the use of tools.

Also Plain and Corrugated Metal types.

See: Riser

FMPX

Female Pipe Swivel Connection.

GPH

Gallons Per Hour.

GPM

Gallons Per Minute.

ID

Inside Diameter

IPS,

Slip Joint

Internal Pipe Swivel Connection. (Female) Same as Slip Joint, 1/2" IPS Faucet, 7/8" IPS Toilet.

See: Straight Pipe Threads

MIP

Male Iron Pipe Connection.

MPX

Male Pipe Swivel Connection

NOM Comp,

Nominal Compression

NOM usually refers to the Inside Diameter of trade sizes of Copper pipes and some CPVC pipes. Not for Iron Pipe Connections.

For example: 1/2" NOM Comp. fittings are actually standard 5/8" SAE compression fittings, because the 1/2" I.D. trade size copper pipe is 5/8" O.D.  A 1/2" NOM Comp stop valve would attach directly to a 5/8" OD (1/2" trade size) copper pipe where it comes out of the wall.

See: Compression

NPS

National Pipe Straight Threads Standard, IPS.

NPT

National Pipe Tapered Threads Standard, FIP, MIP

OD

Outside Diameter

OEM

Original Equipment Manufacturer

PE

Polyethylene Plastic Material

PEX

Cross Linked Polyethylene Plastic Material. Stronger than PE

Potable Liquid

Fit to drink

PVC

Poly Vinyl Chloride Plastic Material

Riser,

Flex Riser

A metal or plastic tube that connects your faucet to the water supply stop valve. Usually made of copper. Metal Flex Risers are corrugated to facilitate bending.

Use care when installing all metal types, as they will work harden and crack or break if they are bent repeatedly in the same place. Select a connector of adequate length to avoid sharp bends, and bend gradually. A sharp bend or too short in length may put a kink in the tube, causing it to fail prematurely.

See: Flexible Water Connector

SAE

Society of Automotive Engineers Standard

SAE

Threads

UNC, UNF

A standard kind of straight thread used on fittings, nuts, and bolts.

Not for Pipe Connections.

For example: A 1/2"-13 SAE thread is 1/2" OD - 13 Threads Per Inch.

A 1/2"-20 SAE thread is 1/2" OD - 20 Threads Per Inch.

Same as 1/2-13 UNC and 1/2-20 UNF

Slip Joint,

IPS

Same as IPS. (Female) 1/2" IPS Faucet, 7/8" IPS Toilet. Internal Pipe Swivel Connection.

See: Straight Pipe Threads

Stem

A rod or pipe that connects the float to the valve arm.

A 3/8"-16 Stem is a 3/8" diameter solid rod with UNC threads.

A 3/8" NPT Stem is a 3/8" trade size pipe, with tapered pipe threads.

Also the part that turns on a stop valve or faucet.

Stops,

Supply Stops,

Straight Stops,

Angle Stops.

Those little valves under your sink or toilet that shut off the Hot and/or Cold water supplies to your faucet or toilet.

Straight Pipe Threads,

FIP Straight,

MIP Straight,

NPS, IPS, Slip Joint,

Faucet Threads,

Toilet Threads.

A special kind of straight thread used only on Iron pipe, Toilet, and Faucet pipefittings. A Cone Seal or gasket is usually included, because straight threads will not form a complete seal without a gasket of some kind.

Unlike tapered threads, thread sealants should not be used with straight threads, and may actually interfere with proper installation, causing them to leak - or the sealant can act as a lubricant and make it hard to tell if the connection is over tightened. Connections should be firmly and securely tightened against the seal, but care should be taken to avoid over-tightening the joint. For metal fittings, hand tight plus 1/4 to 1/2 turns is usually sufficient. Plastic Wing Nut Fittings are designed to be hand tightened only, without the use of tools.

For example: A 1/2" FIP straight thread fits standard 1/2" trade size Iron pipe or Faucet Connections (1/2" ID-7/8" OD). Same as 7/8"-14 NPS and 1/2" IPS or Slip Joint.

For example: A 7/8" IPS straight thread fits Toilet connections. Same as 15/16" NPS and 7/8" Slip Joint or Ballcock.

Straight pipe threads do not form a tight seal, but are often used with a flange, gasket and locknut where a pipe or valve goes through a tank wall.

Also used with a gasket or nosecone seal for 1/2" IPS Faucet and angle stop connections, 1/2" Iron Pipe Connections, 7/8" IPS Toilet connections, etc. Same as Slip Joint.

See: Tapered Pipe Threads

Supply Kit

Usually a kit of all parts needed to connect a faucet or toilet to the pipes coming out of the wall. Usually includes stop valves, water connectors, and escutcheons.

Sweat,

NOM Sweat,

Nominal Sweat,

Solder Connection

A soldered pipe connection. NOM usually refers to the Inside Diameter of trade sizes of Copper pipes. Not for Iron Pipe Connections.

For example: 1/2" NOM Sweat fittings are actually 5/8" ID, because the 1/2" I.D. trade size copper pipe is 5/8" O.D.  A 1/2" NOM Sweat stop valve would be soldered directly to a 5/8" OD (1/2" trade size) copper pipe where it comes out of the wall.

Be sure that the pipe is cut squarely, and that all parts are clean metal before soldering. Use care to avoid getting the stop valve too hot when soldering. A wet rag may help. Be very careful not to let solder and/or acid fluxes drip on other nearby connectors and fittings, especially any kind of flexible gas connectors.

Tapered Pipe

Threads

FIP, MIP, NPT

A standard kind of thread used only on Iron pipe and pipe fittings.

For example: A 1/2" FIP thread fits standard 1/2" trade size Iron pipe (1/2" ID-7/8" OD). Same as 7/8"-14 NPT.

Tapered pipe threads do not need a gasket or cone seal, but a thread sealant must be applied to the male threads only, before the joint is assembled. Use care to avoid getting sealant inside the pipe. Unlike straight threads, tapered thread joints seal better the more they are tightened, making them essential for leak free Iron Pipe joints.

A female straight thread fitting or slip joint connection may be attached to a tapered male thread, as long as a gasket or seal is incorporated into the female fitting design. A thread sealant alone would not seal.  In this case, a thread sealant may actually interfere with proper installation, causing the joint to leak.

Female tapered threads are not suitable for Faucet or Toilet Connections. Even if you use a thread sealant, a female tapered thread fitting may not seal if it is attached to a male straight thread like a faucet or toilet connection.

Generally, do not mix Tapered with Straight Thread pipes and fittings unless special seals are provided.

See: Straight Pipe Threads

TPI

Threads Per Inch

UNC or UC or NC

Unified National Coarse Thread (National Coarse)

A standard kind of Coarse straight threads used on fittings, nuts, and bolts.

Not for Pipe Connections.

UNF or UF or NF

Unified National Fine Thread (National Fine)

A standard kind of Fine straight thread used on fittings, nuts, and bolts.

Not for Pipe Connections.

Uni-Flex

One-piece stop and riser combination. One-piece supply.