CPI compression fittings for tube

CPI is Parker’s single-ferrule instrumentation fitting developed for leak-free, robust tube connections in process, energy and instrumentation systems. The fitting is easy to install, withstands high temperatures and heavy vibration, and is available in a wide range of sizes, materials and end configurations.

Why choose CPI?

Single ferrule for fast assembly.
Leak-free metal-to-metal seal with two primary sealing points.
High resistance to vibration and thermal cycling.
Various materials: 316 stainless steel as standard – also steel, brass, aluminium and titanium.
Threads and ends to ISO and ANSI standards (e.g. metric/imperial, NPT/BSP and more).
Qualification tested in accordance with ASTM F1387 (instrumentation fittings).

Unique seal – how CPI works

The CPI single ferrule grips and seals against both the tube and the fitting body, creating two metal-to-metal sealing zones. The design minimises the number of components and potential leak paths, providing a stable, repeatable seal – even under dynamic load.

Materials, sizes and end configurations

Materials: 316SS as standard; options in brass, aluminium, titanium.
Tube: suitable for metric and imperial tube dimensions (depending on series).
Shapes and ends: straight, elbow, tees, bulkhead, male/female threads, NPT/BSP, and more.
Surface requirements: use tube with the correct hardness, wall thickness and surface finish for optimal sealing.

Typical applications

Process instrumentation (pressure, flow, level, analysis).
Energy and power plants.
Oil & gas, petrochemical and chemical processing.
Pharmaceutical and food processing (with appropriate material selection and cleaning).

CPI vs. A-LOK (quick overview)

CPI: single ferrule, fewer components, fast assembly and service.
A-LOK: twin ferrule, preferred in some applications for extra gripping force and redundancy. Read more about A-LOK here.

The choice depends on the requirements of the installation, the tube material/hardness and internal standards. Both product families are qualified as instrumentation fittings (ASTM F1387).