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Internal unions - standard

Internal unions have female threads and a fitting detail for zero volume fittings. The nuts have male (external) threads. Bulkhead versions can be mounted through an instrument panel or on a bracket.

Standard material is 300 series stainless or PEEK. Also available in Hastelloy C, gold-plated stainless, and titanium. Read about properties of metals and polymers.

Sizes available:

In metal: 1/32", 1/16", 1/8", 1/4"
In PEEK: 1/32" fingertight, 1/16" fingertight, 1/16" hex, 1/8" hex

Product numbers

Select a material to jump to product numbers:

Stainless steel
PEEK

Tech tip

For special materials and/or smaller bores:
Microvolume connectors offer a complete range of 1/32" and 1/16" unions in various metals and polymers, with bore sizes ranging from .006" (0.15 mm) to .040" (1.0 mm).

Our new Cheminert nanovolume connectors, for high resolution capillary HPLC, connect fused silica tubing of various sizes, as well as PEEK and VICI's 1/32" electroformed nickel tubing.

Further reference

About unions
Internal unions
Standard
Bulkhead
External unions
Standard
Bulkhead
1/32" ultra low mass external unions
Microvolume unions
Nanovolume unions
External/internal unions
Reducing unions
Unions with 1/4-28 fittings

Standard internal unions - stainless steel

Tubing OD	Bore	Product No.
1/32"	0.15 mm	ZU.5XC
	0.25 mm	ZU.5
	0.50 mm	ZU.5L
	1/32"	ZU.5T
1/16"	0.15 mm	ZU1XC
	0.25 mm	ZU1C
	0.50 mm	ZU1M
	0.75 mm	ZU1
	1.0 mm	ZU1L
	1/16"	ZU1T
1/8"	0.75 mm	ZU2
	2.0 mm	ZU2L
	1/8"	ZU2T
1/4"	0.75 mm	ZU4
	4.6 mm	ZU4L
	1/4"	ZU4T

Standard internal unions - PEEK

Tubing OD	Bore	Product No.
1/32" fingertight	0.25 mm	ZU.5FPK
	0.50 mm	ZU.5LFPK
	1/32"	ZU.5TFPK
1/16" fingertight	0.25 mm	ZU1CFPK
	0.50 mm	ZU1MFPK
	0.75 mm	ZU1FPK
	1/16"	ZU1TFPK
1/16" hex	0.25 mm	ZU1CPK
	0.50 mm	ZU1MPK
	0.75 mm	ZU1PK
	1/16"	ZU1TPK
1/8" hex	0.75 mm	ZU2PK
	2.0 mm	ZU2LPK
	1/8"	ZU2TPK