Stop Valves by Pipe Type: Compression, Sweat, PEX, CPVC

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Quick answer from a licensed plumber: A stop valve is chosen by its inlet, which must match the pipe at the wall, and its outlet, which is 3/8-inch OD compression for almost every faucet, toilet and dishwasher line. Bare 1/2-inch copper (5/8-inch outside) takes a 1/2-inch nominal compression stop, or sweat or push-connect. A threaded adapter takes FIP. Crimp-ring PEX takes a crimp PEX barb, PEX-A a cold expansion barb, CPVC a solvent weld stop, and press systems a press stop. Buy the 1/4-turn version where BrassCraft makes one (its G2 line has no sweat inlet), angle for a wall stub and straight for a floor stub.

The everyday one: Eastman 10738LF 1/4-turn angle stop, 5/8-inch OD (1/2-inch nominal) compression x 3/8-inch OD compression for a 1/2-inch copper stub out of the wall (sold by Amazon on October 3, 2026; the BrassCraft G2CR19X we used to link was third-party seller only that day).

Step 1: Identify the Stub-Out

A stop valve is named by its inlet (what it joins to the pipe) and its outlet (what the supply line screws onto). The outlet is nearly always 3/8-inch OD compression for a faucet, toilet or dishwasher, so the inlet is the decision, and BrassCraft’s catalog lists the choices for its 1/4-turn stops: “Press Connect,” “Compression,” “FIP,” “CPVC,” “Crimp PEX Barb,” “Cold Expansion PEX Barb,” “Push Connect,” and its multi-turn line adds “Sweat x Compression.” Look at the pipe coming out of the wall or floor, and at whatever the old valve did to it.

The trap for beginners is the “1/2-inch” on the box. A compression stop marked 1/2-inch nominal fits a copper tube that measures 5/8-inch across the outside; the Amazon listing for BrassCraft’s 4-pack puts it plainly, “Inlet: 1/2” Copper Pipe (1/2” Nominal Compression); Outlet: 3/8” OD Compression.” Measure the outside of the pipe with calipers if the old valve is gone: 5/8-inch OD is 1/2-inch nominal copper, and the same stop fits 1/2-inch PEX only with a stiffener inside the tube.

Step 2: Angle or Straight, 1/4-Turn or Multi-Turn

Angle stops turn the flow 90 degrees for a pipe that comes out of the wall; straight stops are for a pipe that comes up through the floor. BrassCraft: “The angle valve is most often used where the water pipe enters the room from the wall.” On the handle, its 1/4-turn G2 stops “control water flow at the fixture or appliance with an easy 90-degree turn of the handle. Innovative, one-piece shut-off mechanism works smoothly with no freeze-ups. Sure-grip handle removes easily to prevent accidental operation during rough-ins.” Its multi-turn stops still exist in most inlet types, including the sweat versions and the ones with a “5” Sweat Extension Tube,” and they turn off “With a few turns of the valve handle.” Our under-sink shut-off valve picks explain why the 1/4-turn is the default for a replacement.

One temperature note from BrassCraft’s own listing: its standard stops are “For use in potable water distribution systems. Not intended for recirculating water systems that produce continuous use temperatures above 115° F. For those applications, use our KT™ series ball stops.”

I send an occasional note when a new guide goes up — repairs worth doing yourself, and the parts that actually last. No spam, no course funnel; written by a licensed Georgia plumber.

Step 3: Outlets That Are Not 3/8

Not every fixture takes a 3/8-inch compression line. BrassCraft lists “Compression x Slip-Joint” and “FIP x Slip-Joint” stops for the 7/16-inch slip-joint tube older faucets used, a 1/4-inch OD compression outlet for ice makers and humidifiers (its “1/2 in. Nom Crimp PEX Barb x 1/4 in. O.D. Comp Angle Stop”), “FIP x Flare” and “Sweat x Flare” for flared copper, and “Dual Outlet” and “Dual Outlet Dual Shut Off” stops that feed a faucet and a dishwasher from one stub. Check the old supply line nut before assuming 3/8. (The dishwasher end of that line is in our dishwasher supply line guide.)

Fitting a Compression Stop

Clean the stub to bright metal, slide on the nut and then the ferrule, push the valve on until the tube bottoms in the body, and tighten the nut by hand plus about a turn with a wrench while holding the valve body with a second wrench. Point the outlet where the supply line needs to go before the final tightening; a compression stop cannot be turned once the ferrule bites. Open the main, then open the stop slowly and watch the nut for a minute. For PEX, the insert goes in first; for sweat, the valve’s stem and washer come out before heat goes on; for CPVC, use the CPVC cement (not PVC cement; the difference is in PVC vs CPVC pipe) and give it the full cure time before pressurizing.

FAQ

What size shut-off valve fits a 1/2-inch copper pipe?

A 1/2-inch nominal compression stop, which fits copper tube that measures 5/8 inch across the outside. BrassCraft lists it as 1/2 in. Nom Comp inlet x 3/8 in. OD Comp outlet, and says the same stop fits PEX with a stainless steel tube insert.

Compression, sweat, PEX or FIP: which stop valve do I need?

Match the pipe: compression or push-connect on bare copper (sweat if you solder), FIP on a threaded adapter or iron pipe, crimp PEX barb on crimp-ring PEX, cold expansion PEX barb on PEX-A, CPVC solvent weld on CPVC. The 3/8-inch compression outlet is the same on all of them.

Is a 1/4-turn stop better than a multi-turn stop?

For a replacement, yes: BrassCraft’s 1/4-turn stops close with a 90-degree turn, use a one-piece shut-off mechanism with no freeze-ups, and come in compression, FIP, CPVC, crimp and cold-expansion PEX, push and press inlets (not sweat). Multi-turn stops still exist, including sweat versions with a 5-inch extension tube.

Angle stop or straight stop?

Angle when the pipe comes out of the wall, straight when it comes up through the floor. BrassCraft says the angle valve is most often used where the water pipe enters the room from the wall.

Can I use a compression stop on PEX?

BrassCraft says its compression stops are compatible with copper or PEX, but PEX installations require a stainless steel tube insert. A crimp or cold-expansion PEX barb stop avoids the insert.

Why Trust Plumbing Picks

Plumbing Picks is written by a licensed Georgia journeyman plumber. Every part number, model list, size, setting and fit on this page comes from the manufacturer pages and documents listed below, which we opened and read; product details come from those makers and from the Amazon listings, not from hands-on testing. Each linked product was shipped or sold by Amazon, new and in stock, when we checked on October 3, 2026. Where a link goes to Amazon we may earn a commission at no extra cost to you. Nobody pays to be included here. More on who writes this and how we pick.

Sources

• BrassCraft: Water Stops (configurations by connection)
• BrassCraft: G2 Series 1/4 Turn Stops
• BrassCraft: 1/4 Turn Stops (18 inlet/outlet families)
• BrassCraft: Multi-Turn Stops (26 inlet/outlet families)
• BrassCraft: G2CR19 1/2″ Nom Comp x 3/8″ OD Comp 1/4-turn angle stop
• BrassCraft: G2CEPX19 1/2″ Nom cold expansion PEX barb x 3/8″ OD Comp 1/4-turn angle stop
• BrassCraft: BRPX19 1/2″ Nom crimp PEX barb x 3/8″ OD Comp multi-turn angle stop

Bottom Line

Measure the stub (5/8-inch OD is 1/2-inch copper), read what the old valve did to it, and buy the same inlet in a 1/4-turn body: compression, FIP, crimp PEX, expansion PEX, CPVC or press (BrassCraft’s G2 1/4-turn line has no sweat inlet; its sweat stops are in the multi-turn line). Angle for the wall, straight for the floor, 3/8 outlet unless the old nut says otherwise.