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Table of Contents
Various male fittings used in vacuum applications. Upper left: Swagelok tube fitting, upper right: NPT, lower left: VCR, lower right, VCO
Swagelok tube fitting
Above: male Swagelok tube fitting
Very common in many applications, usually with 1/4“ OD tube size.
Components of a connection:
- Fitting body (female side)
- Nut
- Front ferrule (large cone)
- Back ferrule (washer like piece)
Installing
Steps [STFI]:
- Ensure that tubing is bur free
- Insert ferrule into mating service
- Attach nut but don't tighten it (just needs to guide tube at this point)
- Insert tubing into nut against ferrule
- Tighten using wrench
- 1/4”: 1-1/4 turns
- 1/16“, 1/8”, 3/16“: 3/4 turn
- Support other side using another wrench or vice
Tip: mark nut with a pen before turning to make it more obvious where in the turn you are
Use Swagelok gap inspection gauge to inspect distance: it should not fit if the fitting is sufficiently tight [STFI]
Re-installing
When disassembling, strip the connection so that original position can be determined
Steps [STFI]:
- Insert tube + ferrule assembly into mating service
- Slide down nut and finger tight to original position
- Tighten it “slightly”
Do not use gap inspection gauge [STFI]
VCR
Above: male VCR fitting (no gasket installed)
Uses a knife edge on consumable metal gaskets to achieve seal.
Components of a connection [Installing VCR]:
- Body (the male side)
- Gasket
- Gland (the female side)
- Silver plated female nut
Body has drilled out holes for leak testing.
Since these are knife edges they must be protected against damage. Above: cap to protect edges when not connected
Gasket types
Above: used retainer gasket
Look like washers. Ex: stainless steel silver plated 0.25”: SS-4-VCR-2
Types [Installing VCR]:
- Retainer gasket
- Side load retainer gasket
- Can be installed in tight spaces
- Non-retain gasket
Materials [Installing VCR]:
- Stainless (ex: SS-8-VCR-2, blue bag, 0.5“)
- Tighten: 1/8 turn
- Nickel (ex: NI-8-VCR-2, black bag, 0.5”)
- Tighten: 1/8 turn
- Copper
- Tighten: 1/4 turn
- Aluminum
- Tighten: 1/4 turn
Installing
Retainer gasket [Installing VCR]:
- Snap gasket onto male gland
- Tighten female nut finger tight
- Use pair of wrenches to tighten
Side load gasket [Installing VCR]:
- Slide gasket onto male gland
- Tool available to pick up
- Tighten female nut finger tight
- Use pair of wrenches to tighten
Non-retain gasket [Installing VCR]:
- Place gasket into female nut
- Tool available to pick up
- Tighten female nut finger tight. Should engage to last thread if installed properly
- Use pair of wrenches to tighten
VCO
Above: male VCO fitting (no gasket installed)
VCO is similar to VCR except that instead of using consumable metal gaskets it uses o-rings.
References
- Swagelok tube fittings installation (STFI): https://www.youtube.com/watch?v=FdthSQDH8qk
- Installing a VCR Metal Gasket Face Seal Fitting (Installing VCR): https://www.youtube.com/watch?v=5z_ZRt51sqo