Guide · Mainline fittings
Compression, barbed or locking-nut drip fittings: how each one grips
How compression, barbed-insert, locking-nut and push-to-connect drip fittings grip the tube, which size each is listed by, and which ones makers call reusable.
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Short answer
A compression fitting grips the outside of the tube, so it is sized by OD. A barbed insert goes inside, so it is sized by ID or a metric family. A locking-nut fitting has a barb plus a collar and is often listed by both. Pick the type your tubing's documented size supports.
Compression: grips the outside
You push the tube into the fitting and an internal insert grips its outside wall. Because the grip is on the outside, makers list compression fittings by OD.
- DIG color-codes its compression inserts by OD; for example, its green insert is listed for .620-.630 in OD tubing.[1] Our insert color guide has the full list.
- DIG rates its compression fittings for up to 60 PSI and recommends 15 to 35 PSI.[1]
- Rain Bird lists its Easy-Fit compression fittings for 0.63-0.70 in OD tubing.[2] Rain Bird says its Easy-Fit adapters are not barbed fittings and go only into Easy-Fit compression fittings.[2]
Barbed insert: grips the inside
A ridged barb is pushed into the tube, and the tube's own stretch holds it. That makes the inside size the one that matters.
- DIG sells a range of 1/2 in barbed fittings that it labels 16 and 17 mm.[3] The page does not give a barb diameter.
- Rain Bird describes its XF dripline insert fittings as 17 mm barb-style fittings rated 0 to 50 psi.[4]
Locking-nut: a barb plus a collar
These are sold as "spin-lock", "nut-lock" or "universal" fittings. A barb goes inside and a nut or collar tightens over the outside, so makers often state both sizes.
- DIG lists its NUTLOC fittings for .530, .600 or .620 in ID, described as .630-.710 in OD.[5]
- Raindrip lists its Smart Loc S5600UB coupling for three ID x OD pairs: .520 x .620, .600 x .700 and .620 x .710 in; it secures with a barb and a twist-on nut.[6]
- Orbit's 67466 coupling is listed for .620-.710 in OD; you slide the tube over the insert, hand-twist the outer nut, and loosen the nut to remove the tube.[7]
- Mister Landscaper describes its MLF 1/2 in fittings as reusable locking-collar fittings with built-in O-rings.[8]
- Perma-Loc is another collar fitting. Drip Depot, a retailer, says not to remove the swivel collar: twist it back, push the tube over the barb until it is covered (about 0.5 in), then tighten.[9] Drip Depot also says Perma-Loc fittings for drip tape and for poly tubing are not interchangeable.[9]
Push-to-connect
Orbit's 67491 Drip-Lock coupling is a push-on fitting with a release tab, listed for .690, .700 and .710 in OD tubing.[10] That is a different mechanism and a different range from Orbit's 67466.
Side by side
| Type | Grips | Size it by | Maker examples | Removal |
|---|---|---|---|---|
| Compression | Outside wall | OD | DIG compression, Rain Bird Easy-Fit | Not stated as reusable on the pages we read |
| Barbed insert | Inside wall | ID or metric family | DIG 16/17 mm, Rain Bird XF 17 mm | Not stated |
| Locking-nut | Barb inside, nut outside | ID and OD, or an OD range | DIG NUTLOC, Raindrip Smart Loc, Orbit 67466, Mister Landscaper MLF | Orbit 67466 and Mister Landscaper MLF are stated as reusable |
| Push-to-connect | Push-on, release tab | OD | Orbit 67491 Drip-Lock | Release tab |
Fittings with a stated range
These three couplings each state the sizes they take. Choose the one whose range covers your tubing.
Picks that fit3 products
Easy-Fit EFC25-1PS (compression) is listed for 0.63-0.70 in OD; Orbit 67466 (locking nut) for .620-.710 in OD; Raindrip Smart Loc S5600UB (barb and nut) for .520 x .620, .600 x .700 and .620 x .710 in. Choose by your tubing's OD.
Choose the Rain Bird Easy-Fit EFC25-1PS for 0.63-0.70 in tubing
Rain Bird Easy-Fit EFC25‑1PS 1/2 in universal compression coupling (0.63‑0.70 in OD)
Choose the Orbit 67466 for the widest stated OD range
Orbit 67466 1/2 in universal drip coupling (0.620‑0.710 in OD)
Choose the Raindrip Smart Loc S5600UB when you know your ID x OD pair
Raindrip Smart Loc S5600UB universal coupling (0.620, 0.700 and 0.710 in OD)
On Amazon, check that "Ships from / Sold by" is Amazon.com or the brand before you buy.[11]
Next
- The drip connection type finder
- Connection types: compression, barbed insert and locking nut
- What "universal" means on drip fittings
Questions
Which is better, compression or barbed drip fittings?
Neither in general. A compression fitting is sized by the tube's outside diameter and a barbed insert by its inside diameter or a metric family, so choose the type your tubing's documented size supports.
What is a spin-lock drip fitting?
A fitting with a barb that goes inside the tube and a nut or collar that tightens over the outside. Raindrip's Smart Loc secures with a barb and twist-on nut, and Orbit's 67466 locks with a hand-twisted outer nut.[6][7]
Are drip fittings reusable?
Only where the maker says so. Orbit says the 67466 coupling is reusable by loosening its nut, and Mister Landscaper calls its MLF locking-collar fittings reusable.[7][8]
Can I use drip tape fittings on poly tubing?
Not Perma-Loc ones, according to Drip Depot, which says Perma-Loc fittings for drip tape and for poly tubing are not interchangeable.[9]