Why choose the QF family

QF quick-connects provide a compact full-flow path without an internal orifice restriction. They are intended for applications where the pressure drop of a conventional shutoff coupling would be undesirable. Sizes QF4, QF8, QF12 and QF16 scale from 1/4 in. connections through 1 in. pipe connections in the catalog tables.

The seal O-ring can be replaced without disassembling the body. QF is not a shutoff coupling: the line must be isolated, drained and depressurized before separation. The catalog explicitly warns not to uncouple QF quick-connects under pressure.

Pressure envelope

Size group	316 SS rating at 40 to 100 °F	Brass rating at 40 to 100 °F
QF4	6000 psig (413 bar)	4000 psig (275 bar)
QF8	6000 psig (413 bar)	3000 psig (206 bar)
QF12	4000 psig (275 bar)	2000 psig (137 bar)
QF16	4000 psig (275 bar)	2000 psig (137 bar)

Pressure rating can be limited by the selected end connection and decreases with temperature. Review the pressure-temperature table and the rating of the connected tubing, hose, adapter and instrument.

Flow and connection examples

The QF tables list Cv separately for each connection pattern. Representative male NPT stem values show how capacity increases with size:

Series / example	Connection	Catalog Cv	Minimum orifice
QF4-S-4PM	1/4 in. male NPT	1.7	0.24 in. (6.1 mm)
QF8-S-8PM	1/2 in. male NPT	11.5	0.50 in. (12.7 mm)
QF12-S-12PM	3/4 in. male NPT	23.6	0.72 in. (18.3 mm)
QF16-S-16PM	1 in. male NPT	39.0	0.88 in. (22.4 mm)

These values apply to the listed stem. For a coupled assembly using unlike end connections, MS-01-138 instructs users to average the two connection Cv values. Verify that the hose bore or adjacent component does not become the actual restriction.

Materials and media compatibility

QF is cataloged in 316 stainless steel and brass. Material prefix SS identifies stainless construction and B identifies brass. Seal and internal-component compatibility must be checked against the process medium, cleaning agent and temperature. For oxygen service, high-purity gas or aggressive chemicals, specify cleaning and lubricant requirements as part of the complete assembly review.

End-connection choices

The manual lists Swagelok tube fittings, female and male NPT, ISO/BSP tapered threads, ISO/BSP parallel connections with a 60° cone profile, and size-dependent alternatives. Common ordering codes include:

• 400, 600, 810, 1210 and similar tube-fitting size codes.
• 4PM, 6PM, 8PM, 12PM, 16PM for male NPT patterns.
• 4MT, 8MT, 16MT for ISO/BSP tapered patterns.
• 4MS, 8MS and related codes for ISO/BSP parallel patterns.

Do not infer thread form from nominal size alone. Confirm the suffix, sealing method and mating connection standard.

Body and stem protectors

Protectors guard open bodies and stems against dirt and impact. They are available in 316 stainless steel or plated brass with stainless lanyard components. They are not pressure-containing devices. Catalog base numbers include -QF4-SP / -QF4-BP and corresponding QF8, QF12 and QF16 versions; add the material prefix to create the ordering number, for example SS-QF4-SP.

Selection workflow

1. Calculate the required flow and allowable pressure drop.
2. Choose QF4, QF8, QF12 or QF16 based on bore, connection and Cv.
3. Select 316 stainless steel or brass after compatibility review.
4. Select the exact body and stem end connections.
5. Check pressure ratings at the maximum operating temperature.
6. Reserve axial clearance for coupling and support the connected hose.
7. Add protectors if the halves will remain uncoupled in the work area.
8. Define a depressurization and drainage procedure—QF must not be separated under pressure.

The product grid may contain only a subset of the catalog's many combinations. If the exact connection is not listed, use the PDF ordering table to identify the required base number for quotation.