Claw-Clamp Couplings | McMaster-Carr

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	Connection Style Connection Style	Show

Claw Clamp

	Connection Style Connection Style	Hide

	Trade Number Trade Number

100

160

	Type Type


Connector	Adapter

	System of Measurement System of Measurement

Inch

	For Tube OD For Tube OD

1 1/2"

2 1/2"

	High Vacuum Connection Type High Vacuum Connection Type

ISO-KF

ISO-K

	Material Material

Stainless Steel

	Flange OD Flange OD

	Shape Shape

	Straight

	For Tube Material For Tube Material

316/316L Stainless Steel

304/304L Stainless Steel

	Connection Type Connection Type

	Tube

	REACH (Registration, Evaluation, Authorization and Restriction of Chemicals) REACH (Registration, Evaluation, Authorization and Restriction of Chemicals)

REACH Compliant

	RoHS (Restriction of Hazardous Substances) RoHS (Restriction of Hazardous Substances)

RoHS Compliant

	DFARS (Defense Acquisition Regulations Supplement) DFARS (Defense Acquisition Regulations Supplement)

DFARS Specialty Metals
COTS-Exempt

	Sterilize With Sterilize With

Steam (Autoclaving)

	Maximum Pressure Maximum Pressure

5 psi @ 72° F

Not Rated

	Maximum Temperature Maximum Temperature

250° to 499° F

Not Rated

	Minimum Temperature Minimum Temperature

-49° to 0° F

Not Rated

	Vacuum Rating Vacuum Rating

High

	Length Length

	Maximum Vacuum Maximum Vacuum

1 × 10^-9 torr @
72° F

	Specifications Met Specifications Met

ISO

	Gasket Connection Style Gasket Connection Style

Standard

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52 Products

How to Identify and Measure Fittings

Pipe size is an industry designation, not the actual size. View information about how to measure threaded and unthreaded pipe and pipe fittings.

For Use With:
Fittings with Gasket End: Air, Argon, Helium, Nitrogen
All Other Fittings: Air
Temperature Range: 0° to 300° F
Tubing: Use with 304/304L or 316/316L stainless steel
Specifications Met: ISO 2861

Instead of a gasket, these fittings have a special ring that is designed for high-vacuum applications, such as vacuum coating and heat treating, leak testing, and analyzing gases. Also known as KF, QF, and NW fittings, they are the most common type of connection in high-vacuum systems. Connect with a clamp and another quick-clamp fitting for fast, easy access to your line. To use fittings in pressure applications, use a pressure-rated ring (sold separately).

304 stainless steel fittings have very good corrosion resistance.

Note: To complete a connection, you’ll need two quick-clamp fittings, a ring, and a clamp (all sold separately).

Straight Adapters, Tube × Claw-Clamp Tube

Fittings with claw-clamp end are often used to connect high-vacuum components with large-diameter connections, such as coating or heat-treating equipment, to components with smaller connections such as gauges, filters, or pumps. Also known as ISO-K fittings, they connect with four claw clamps and a ring (sold separately).

Quick-Clamp Tube Connection				Claw-Clamp Tube Connection
For Tube OD	Flange OD	Trade Number	High Vacuum Connection Type	For Tube OD	Flange OD	Trade Number	High Vacuum Connection Type	Max. Vacuum	Max. Pressure		Each
1"	1.57"	25	ISO-KF	2 1/2"	3.74"	63	ISO-K	1 × 10 ^-9 torr @ 72° F	5 psi @ 72° F	00000000	0000000
1 1/2"	2.16"	40	ISO-KF	2 1/2"	3.74"	63	ISO-K	1 × 10 ^-9 torr @ 72° F	5 psi @ 72° F	00000000	000000
1 1/2"	2.16"	40	ISO-KF	3"	4.33"	80	ISO-K	1 × 10 ^-9 torr @ 72° F	5 psi @ 72° F	00000000	000000
1 1/2"	2.16"	40	ISO-KF	4"	5.12"	100	ISO-K	1 × 10 ^-9 torr @ 72° F	5 psi @ 72° F	00000000	000000
2"	2.95"	50	ISO-KF	2 1/2"	3.74"	63	ISO-K	1 × 10 ^-9 torr @ 72° F	5 psi @ 72° F	00000000	000000
2"	2.95"	50	ISO-KF	3"	4.33"	80	ISO-K	1 × 10 ^-9 torr @ 72° F	5 psi @ 72° F	00000000	000000
2"	2.95"	50	ISO-KF	4"	5.12"	100	ISO-K	1 × 10 ^-9 torr @ 72° F	5 psi @ 72° F	00000000	000000

Ring for 4" Tube OD (Claw-Clamp End)	0000000	Each	000000
Double-Claw Clamp	0000000	Each	0000
Double-Claw Clamp	0000000	Each	0000
Double-Claw Clamp	0000000	Each	0000
Double-Claw Clamp	0000000	Each	0000
Ring for 3" Tube OD (Claw-Clamp End)	000000	Each	00000
Ring for 2 1/2" Tube OD (Claw-Clamp End)	0000000	Each	00000
Double-Claw Clamp	0000000	Each	0000
Double-Claw Clamp	0000000	Each	0000
Double-Claw Clamp	0000000	Each	0000

Clamps

Clamp with Wing Nut

Spring-Loaded Clamp

Clamps (sold separately) tighten by hand. Spring-loaded clamps are also known as toggle clamps.

with Wing Nut
For Tube OD	For Flange OD	Trade Number	High Vacuum Connection Type	Material	Max. Vacuum	Lanyard Length		Each
1"	1.57"	25	ISO-KF	Aluminum	1 × 10 ^-7 torr @ 72° F	__	0000000	000000
1 1/2"	2.16"	40	ISO-KF	Aluminum	1 × 10 ^-7 torr @ 72° F	__	0000000	00000
2"	2.95"	50	ISO-KF	Aluminum	1 × 10 ^-7 torr @ 72° F	__	0000000	00000
Spring Loaded
1"	1.57"	25	ISO-KF	Aluminum	1 × 10 ^-7 torr @ 72° F	__	0000000	00000
1 1/2"	2.16"	40	ISO-KF	Aluminum	1 × 10 ^-7 torr @ 72° F	__	0000000	00000
2"	2.95"	50	ISO-KF	Aluminum	1 × 10 ^-7 torr @ 72° F	__	0000000	00000
Spring Loaded with Lanyard
1"	1.57"	25	ISO-KF	Aluminum	1 × 10 ^-7 torr @ 72° F	5 3/4"	00000000	00000
1 1/2"	2.16"	40	ISO-KF	Aluminum	1 × 10 ^-7 torr @ 72° F	5 3/4"	00000000	00000

Rings

Ring

Ring with Stainless Steel Screen

Ring with Aluminum Outer Ring

Rings (sold separately) consist of a stainless steel inner ring covered by a fluoroelastomer O-ring. Rings with screen have a stainless steel screen to filter out large particles. Pressure-rated rings have an aluminum outer ring to withstand extra pressure.

Rings
For Tube OD	For Flange OD	Trade Number	High Vacuum Connection Type	Inner Ring Material	Max. Vacuum	Max. Pressure		Each
1"	1.57"	25	ISO-KF	304 Stainless Steel	1 × 10 ^-7 torr @ 72° F	Not Rated	0000000	00000
1 1/2"	2.16"	40	ISO-KF	304 Stainless Steel	1 × 10 ^-7 torr @ 72° F	Not Rated	0000000	00000
2"	2.95"	50	ISO-KF	304 Stainless Steel	1 × 10 ^-7 torr @ 72° F	Not Rated	0000000	00000
Rings with Stainless Steel Screen
1"	1.57"	25	ISO-KF	304 Stainless Steel	1 × 10 ^-7 torr @ 72° F	Not Rated	00000000	00000
1 1/2"	2.16"	40	ISO-KF	304 Stainless Steel	1 × 10 ^-7 torr @ 72° F	Not Rated	00000000	00000
2"	2.95"	50	ISO-KF	304 Stainless Steel	1 × 10 ^-7 torr @ 72° F	Not Rated	00000000	00000
Rings with Aluminum Outer Ring
1"	1.57"	25	ISO-KF	304 Stainless Steel	1 × 10 ^-7 torr @ 72° F	100 psi @ 72° F	0000000	00000
1 1/2"	2.16"	40	ISO-KF	304 Stainless Steel	1 × 10 ^-7 torr @ 72° F	75 psi @ 72° F	0000000	00000
2"	2.95"	50	ISO-KF	304 Stainless Steel	1 × 10 ^-7 torr @ 72° F	50 psi @ 72° F	0000000	00000

Hose

Rigid Hose

Flexible Hose

Hose (sold separately) absorbs moderate vibration

4 3/16" Lg.
For Tube OD	Flange OD	Trade Number	High Vacuum Connection Type	Material	Max. Vacuum	Bend Radius	Flexibility		Each
1"	1.57"	25	ISO-KF	304 Stainless Steel	1 × 10 ^-7 torr @ 72° F	__	Rigid	0000000	000000
1 1/2"	2.16"	40	ISO-KF	304 Stainless Steel	1 × 10 ^-7 torr @ 72° F	__	Rigid	0000000	000000
2"	2.95"	50	ISO-KF	304 Stainless Steel	1 × 10 ^-7 torr @ 72° F	__	Rigid	0000000	000000
12" Lg.
1"	1.57"	25	ISO-KF	304 Stainless Steel	1 × 10 ^-7 torr @ 72° F	1 3/8"	Flexible	00000000	000000
1 1/2"	2.16"	40	ISO-KF	304 Stainless Steel	1 × 10 ^-7 torr @ 72° F	2 1/2"	Flexible	00000000	000000
2"	2.95"	50	ISO-KF	304 Stainless Steel	1 × 10 ^-7 torr @ 72° F	3 1/4"	Flexible	00000000	000000
24" Lg.
1"	1.57"	25	ISO-KF	304 Stainless Steel	1 × 10 ^-7 torr @ 72° F	1 3/8"	Flexible	00000000	000000
1 1/2"	2.16"	40	ISO-KF	304 Stainless Steel	1 × 10 ^-7 torr @ 72° F	2 1/2"	Flexible	00000000	000000
2"	2.95"	50	ISO-KF	304 Stainless Steel	1 × 10 ^-7 torr @ 72° F	3 1/4"	Flexible	00000000	000000
39" Lg.
1"	1.57"	25	ISO-KF	304 Stainless Steel	1 × 10 ^-7 torr @ 72° F	1 3/8"	Flexible	00000000	000000
1 1/2"	2.16"	40	ISO-KF	304 Stainless Steel	1 × 10 ^-7 torr @ 72° F	2 1/2"	Flexible	00000000	000000
2"	2.95"	50	ISO-KF	304 Stainless Steel	1 × 10 ^-7 torr @ 72° F	3 1/4"	Flexible	00000000	000000

Claw-Clamp High-Vacuum Fittings for Stainless Steel Tubing

An alternative to bolt-together fittings, these handle larger tube OD sizes and have higher vacuum ratings than quick-clamp fittings. Also known as ISO-K high-vacuum fittings, the clamps have claws that grab hold of fittings with flanged ends. To complete a connection, use a ring and four clamps (sold separately). Not for use in pressure applications.

Double-claw clamps attach to the grooves on the fittings.

Single-claw clamps have a clamp on one end and an exposed bolt on the other. Thread the bolt-end directly into the body of pumps, valves, or other high-vacuum components.

For technical drawings and 3-D models, click on a part number.

Straight Adapters, Tube × Butt-Weld Tube

Straight Adapter, Tube × Butt-Weld Tube

For Tube OD	Flange OD	Trade Number	Wall Thick.	High Vacuum Connection Type	No. of Claw Clamps Required	Material	Max. Vacuum		Each
2 1/2"	3.74"	63	0.065"	ISO-K	4	304 Stainless Steel	1 × 10 ^-9 torr @ 72° F	0000000	000000
3"	4.33"	80	0.065"	ISO-K	4	304 Stainless Steel	1 × 10 ^-9 torr @ 72° F	0000000	000000
4"	5.12"	100	0.083"	ISO-K	4	304 Stainless Steel	1 × 10 ^-9 torr @ 72° F	0000000	000000
6"	7.09"	160	0.109"	ISO-K	4	304 Stainless Steel	1 × 10 ^-9 torr @ 72° F	0000000	000000

Straight Connectors, Tube

Straight Connector, Tube

For Tube OD	Flange OD	Trade Number	High Vacuum Connection Type	No. of Claw Clamps Required	Material	Max. Vacuum		Each
2 1/2"	3.74"	63	ISO-K	4	304 Stainless Steel	1 × 10 ^-9 torr @ 72° F	0000000	0000000
3"	4.33"	80	ISO-K	4	304 Stainless Steel	1 × 10 ^-9 torr @ 72° F	0000000	000000
4"	5.12"	100	ISO-K	4	304 Stainless Steel	1 × 10 ^-9 torr @ 72° F	0000000	000000
6"	7.09"	160	ISO-K	4	304 Stainless Steel	1 × 10 ^-9 torr @ 72° F	000000	000000

Rings

Ring

				Material
For Tube OD	For Flange OD	Trade Number	High Vacuum Connection Type	O-Ring	Inner Ring	Max. Vacuum	Max. Temp., °F		Each
2 1/2"	3.74"	63	ISO-K	Viton® Fluoroelastomer Rubber	304 Stainless Steel	1 × 10 ^-9 torr @ 72° F	400°	0000000	000000
3"	4.33"	80	ISO-K	Viton® Fluoroelastomer Rubber	304 Stainless Steel	1 × 10 ^-9 torr @ 72° F	400°	000000	00000
4"	5.12"	100	ISO-K	Viton® Fluoroelastomer Rubber	304 Stainless Steel	1 × 10 ^-9 torr @ 72° F	400°	0000000	00000
6"	7.09"	160	ISO-K	Viton® Fluoroelastomer Rubber	304 Stainless Steel	1 × 10 ^-9 torr @ 72° F	400°	0000000	00000

Clamps

Double-Claw Clamp

Single-Claw Clamp

Double Claw
For Tube OD	For Flange OD	Trade Number	High Vacuum Connection Type	Material	Bolt Material	Max. Vacuum		Each
2 1/2", 3", 4"	3.74", 4.33", 5.12"	63, 80, 100	ISO-K	Aluminum	18-8 Stainless Steel	1 × 10 ^-9 torr @ 72° F	0000000	00000
6"	7.09"	160	ISO-K	Aluminum	18-8 Stainless Steel	1 × 10 ^-9 torr @ 72° F	0000000	0000
Single Claw
2 1/2", 3", 4"	3.74", 4.33", 5.12"	63, 80, 100	ISO-K	Aluminum	18-8 Stainless Steel	1 × 10 ^-9 torr @ 72° F	0000000	0000
6"	7.09"	160	ISO-K	Aluminum	18-8 Stainless Steel	1 × 10 ^-9 torr @ 72° F	0000000	0000

How to Identify and Measure Fittings

Quick-Clamp High-Vacuum Fittings for Stainless Steel Tubing

Claw-Clamp High-Vacuum Fittings for Stainless Steel Tubing