Smart advice on how to choose the right kind of cam & groove coupling
When trying to figure out the best kind of cam and groove coupling for a task, there are seven major areas to think of to ensure you get the best quality hose assembly. The acronym for this is STAMPED, which stands for: Size (the overall dimensions of the hose required for your particular need); Temperature (ensuring that the parts will stand the temperatures they will be working at); Application (what environment will the hose be used in?); Material (or media being used. What kind of compound or liquid will be processed through the system?); Pressure (how much pressure will be going through the system?); Ends (the fittings and connections – thread type, etc.) and Delivery (when will the system be expected on the job?).
That’s the basics of finding a good coupling, but there is more to the world of cam and groove than just the fit. You need to know the standards, the various fits and the interchangeability of the fits for future- proofing your business.
The standard for cam & groove couplings is based on the US military specification Mil-C-27487 now superseded by A-A-59326A. The Mil-C-27487 specified the casting methods, materials, dimensions, tolerances, pressure ratings, and inspection procedures required. In 1998, the original specification was replaced by a new standard, which guaranteed interchangeability of couplings designed to the same specification.
The European standard EN 14420-7 was approved by CEN in September 2004 and was applied to cam & groove couplings manufactured to the American military standard as outlined above. This American standard does not apply to the hose connection side, but only to the coupling side.
Cam & groove couplings produced to EN 14420-7 are interchangeable with those produced to the original MIL-C-27487 standard, but differ in terms of hose tail design, thread, part number, etc. A flat thread seal has been added to the female threaded parts, and a smooth hose shank complying with EN 14420-2/DIN 2817 has been added for assembly with RK safety clamps complying with EN 14420-2/DIN 2817.
Couplings produced to DIN 2828 are interchangeable with those produced to the original MIL-C-27487 standard, but differ in terms of hose tail design, thread, part number, etc. A flat thread seal has been added to the female threaded parts, and a smooth hose shank complying with DIN 2817 has been added for assembly with RK safety clamps complying with DIN 2817.
Between manufacturers, cam & groove couplings are interchangeable with the exception of ½in, 5in and 8in. The A-A-59326A Mil Specification does not apply to 5in and 8in cam & groove couplings, due to the presence of two versions of cam & groove couplings in today’s market.
Hose shanks with larger serrations are not designed to be assembled with a ferrule or sleeve. Hose damage can result if they are swaged. The larger shank serrations will cut into the inner wall of the hose resulting in leakage or permanent hose failure.
Note: cam & groove couplings should never be used for steam or compressed air applications.
Sometimes standard cam & groove coupling materials, such as stainless steel, are not sufficiently resistant to extremely aggressive chemicals. There are couplings that feature a variety of high-resistance coatings.
ECTFE coatings are designed to resist highly concentrated and aggressive chemicals. Couplings with an ECTFE coating show excellent electric isolating and fire properties and resist to temperatures up to 150°C.
The key quality of a PFA coating is that the temperature resistance is up to 260°C. This effective anti-adhesive layer makes PFA coatings particularly well suited to food and pharmaceutical industry applications.
PTFE couplings can withstand temperatures of up to 260°C. Like PFA coated couplings, these ones have excellent anti-adhesive qualities and are suitable for food industry applications.
PVDF couplings are resistant to highly concentrated and aggressive chemicals and have the advantage of high temperature resistance up to 260°C. These couplings are wear-proof and also suitable for food industry applications.
Experts such as Action Sealtite can offer guidance on the most suitable solution for any application.