If you’re going to set-up a system involving the transfer of fluids, you’re inevitably going to need fittings to connect all the tubing involved in the system. The tube fittings are generally made from brass, steel, stainless steel, and for some rare situations, aluminum. When selecting a tube fitting, be sure to select one that is the proper size, and is rated for the pressure that it will be subjected to.
Figure 1: A-LOK Double Ferrule
At Dale Foster Sales, we offer high quality tube fittings by Parker. Parker manufactures both A-LOK and CPI fittings. While Parker’s fittings may be more expensive than some other manufacturers, it’s been my experience that Parker’s high quality materials and design certainly justify the price. Over time, Parker fittings will outlast discount versions, saving you both time, and unnecessary replacement / rebuild costs.
So what’s the difference between A-LOK and CPI fittings? Other than simplicity, nothing. CPI fittings can be used in the same systems and tubing as A-LOK systems. CPI fittings, in fact, use the same body. The only real difference is that A-LOK fittings use a double ferrule design (Figure 1), where CPI fittings use a single ferrule (Figure 2). The ferrule is the interior portion of the fitting that bites down into the tubing. When a tube fitting wears out, you can normally replace the ferrule and reuse the casing.
Figure 2: CPI Single Ferrule
If I were assembling a control system and needed to choose tube fittings, I personally would go with the CPI fittings. The CPI fittings offer the same effectiveness as A-LOK, but the added benefits of simplicity and ease of use. Since CPI fittings rely on only one ferrule, they have fewer interior parts. If the ferrule ever wears out and needs to be replaced, you have that much less work on your hands. And of course, buying one new ferrule instead of two will save you money.
Properly selected and installed, Parker tube fittings should last for the lifetime of your system. If you would like to know more about tube fittings, or have questions about any other fluid system components, by all means call me at 800-326-6518.