Superior Fluid Solutions · Analytical Instrumentation
How to Cross-Reference Swagelok® Instrumentation Fittings for Analyzer Systems
A sample line is less forgiving than a process line. Here is what to check, and what never to mix, when the fitting feeds an analyzer.
Analyzer panels are usually drawn around one brand of instrumentation fitting, which works fine until that part is back-ordered and the analyzer is waiting on it. According to ISA Fellow Ian Verhappen, writing in Control Global, an online analyzer has to be reliable enough to hold a service factor above 95 percent. A fitting that goes in wrong can undo that on its own. This is a buyer’s guide to cross-referencing Swagelok®, Parker® A-LOK® and Hy-Lok® instrumentation fittings by form, fit, and function for analyzer and sample systems.
Why a sample line is less forgiving
On a utility line, a fitting that holds pressure has done its job. On a sample line it also has to get the sample to the analyzer without changing it. A fitting with a trapped pocket slows the analyzer’s response. A joint that weeps can lose sample, or on a low-pressure line pull in outside air that the analyzer then reads as if it came from the process. A rough bore can hold residue and release it into the next reading.
None of that shows up on the purchase order. It shows up weeks later as an analyzer the operators stop trusting. So a cross-reference for analyzer work has to cover more than the thread and the tube size.
What to check before you cross-reference
Each of these can be answered before you buy:
| Check | Why it matters |
|---|---|
| Tube OD, inch or metric | 1/4 inch and 6 mm tubing are close enough to confuse and different enough to leak. Check this first. |
| Ferrule design | Many instrumentation fittings are double ferrule. Match the ferrule design your drawing calls for. |
| Alloy grade | Corrosion-resistant 316 stainless steel suits most process samples. An aggressive sample may need a specialty alloy. |
| End connection | NPT, tube stub and straight-thread ports look alike on a drawing. Confirm the exact port on the analyzer or filter. |
| Pressure and temperature | Check the rating against the real sample conditions, including any heated or traced sections of the line. |
| Material documentation | If your analyzer house spec requires a material test report, ask for it when you order. |
Superlok® fittings are listed in 316 stainless steel. If your sample chemistry calls for something else, ask before you order.
Never mix parts in a joint
Cross-reference the whole fitting: body, nut and ferrules together. Do not put a nut from one manufacturer on a body from another, or drop one brand’s ferrules into another brand’s fitting. When a panel is being converted, convert complete connections, and keep spare ferrule sets with the fittings they belong to.
The inside of the fitting matters too
The sample only ever touches the inside of a fitting, so the bore matters as much as the outside dimensions. Superlok® is home to the finest interior surface finish of any tube and pipe fitting on the market, which leaves residue fewer places to sit between samples.
The rest of the sample line
Superior Fluid lists the rest of the panel too: tube fittings, unions for lines you need to open for maintenance, needle valves for setting sample flow, inline filters ahead of the analyzer, and check valves where several sample streams share a header, all in corrosion-resistant stainless steel.
We have written about cross-referencing for oil and gas fittings, and about purity in semiconductor fab fittings, which matters for the same reasons it does on an analyzer.
Cross-reference questions
Can I cross-reference Swagelok® instrumentation fittings for an analyzer panel?
Yes, by form, fit, and function, as long as the tube OD, ferrule design, grade, end connection and rating are checked for each line. Send the part numbers from your drawing and each one can be confirmed before you buy.
Can I use Superlok® ferrules in another brand’s fitting?
No. Do not mix nuts, ferrules and bodies from different manufacturers inside one connection. Cross-reference the complete fitting, and keep spare ferrule sets with the fittings they came with.
Do you carry both inch and metric tube sizes?
Tell us the tube OD on each line and we will confirm the matching part and whether it is available. Mixing up 1/4 inch and 6 mm is an easy mistake on an analyzer panel, so it is worth checking first.
Can I get material certification with the order?
Ask for it when you order. If your spec requires a material test report, say so up front so it can be confirmed before the parts ship.
Can I order online instead of waiting on a quote?
Yes. Our tube fittings and valves are listed with pricing and availability so you can order directly. If you would rather have a cross-reference confirmed first, send the part numbers before you buy.
Cross-reference your analyzer panel
Superlok® instrumentation fittings in corrosion-resistant 316 stainless steel, listed with pricing and availability.
Superior Fluid Solutions
Corrosion-resistant Superlok® fittings and valves, cross-referenced by form, fit, and function to your Swagelok®, Parker® and Hy-Lok® part numbers.
Sources
- Ian Verhappen, ISA Fellow, “Basics of Analyzer Sample Systems, Parts 1-2,” Control Global, February 2011. States that the analyzer must be highly reliable so it will maintain a service factor in excess of 95%. controlglobal.com
Technical note: guidance above is general industry practice, not a substitute for engineering on your specific analyzer system. Tube size, material grade and pressure rating are confirmed per order. Shipping note: most in-stock orders placed during business hours ship the same day; orders placed after hours or on weekends ship the next business day.
Swagelok®, Parker®, A-LOK® and Hy-Lok® are registered trademarks of their respective owners. Superior Fluid Solutions and Superlok® are not affiliated with, authorized by, or endorsed by those companies. Cross-references are made by form, fit, and function only.
