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Brass Compression Fitting For Plastic, Copper, & Aluminum Tubing, 0.25 Inch Tube OD To 1/4-18 Female NPT, Straight

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Description & Features

The Danfoss / Eaton brass compression female connector is designed to meet the strict specifications of ASA, ASME, and SAE standards. Crafted from CA360 brass, it ensures reliable performance in instrumentation, hydraulic, and pneumatic systems.

It supports tube outer diameters of 0.25 inches and features a 1/4-18 female NPT thread. The fitting operates efficiently within a temperature range of -65deg;F to +250deg;F when paired with metal tubing. For plastic tubing, users must not exceed the specific tubing temperature range.

With a broad selection of sizes and styles, this connector is ideal for use with aluminum, copper, and certain plastic tubing. However, plastic tubing (except Eaton PT230) requires a 2030 insert for compatibility.

Assembly is straightforward, eliminating the need for flaring. The working pressure can reach up to 2000 psi, based on tube size, provided a 4:1 safety factor is maintained. It has fair vibration resistance, with recommendations to use a long nut for enhanced vibration resistance.

**ECCN:** EAR99

**Supplier Part Number:** 66X4X4

Specifications

Brand
Danfoss Power Solutions (II LLC Aeroquip)
Brand
Aeroquip
Pack Size
1.00
UOM
EA
L
1.03
Supplier Part Number
66X4X4
Thread 1
1/4-18
Tube O.D.
0.25
Tube O.D.
0.25
Alternate Part Numbers
Alternate Part Number C1HQ98, Alternate Part Number MI-00334026, Alternate Part Number MINO-00015X07448, Alternate Part Number MINO-00925F73353
Product Weight
0.07 lbs

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Product Questions & Answers (3)

Question by: Larry G on Feb 26, 2026, 7:07 PM
What kind of tubing can I use with this fitting?
Answer by: Customer Support on Feb 28, 2026, 7:56 AM
It's designed to work with aluminum, copper, and plastic tubing. Keep in mind that plastic tubing, except for Eaton PT230, needs the 2030 insert. It's not recommended for steel tubing, though.
Question by: Lyle Y on Mar 12, 2026, 12:43 PM
got some 1/4 inch OD copper tubing on an old pneumatic line i need to tie into, will this fitting work for that hookup?
Answer by: Customer Support on Mar 13, 2026, 3:36 PM
Copper tubing with a 1/4 inch outer diameter is exactly what this fitting is built around. The female NPT thread on the other end is 1/4-18, so as long as your mating port matches that thread size, you're good to go. No flaring needed either, which makes the job a lot cleaner.
Question by: Terry W on Mar 25, 2025, 10:27 AM
got a 1/4 inch tube line, will this fitting screw into a standard 1/4 npt port?
Answer by: Customer Support on Mar 27, 2025, 9:54 AM
It is made for 0.25 inch tube OD on the compression side and a 1/4-18 female NPT thread on the other end, straight configuration. That means it threads onto a 1/4-18 male NPT connection and grips the 1/4 inch tubing without needing to flare the tube.