Across the ranges, all standard shapes are available to complete a system design, both metric and imperial:. The rugged and durable nature of the fittings makes them suitable for most industrial applications.
The fittings can be supplied with olive, nuts and any appropriate seals. Piping will be required for the connections to be completed. PA11 or 12 and other plasticised or unplasticised piping and other soft plastic piping. Copper annealed and half-hard; double wall brazed steel pipe.
Some manufacturers offer tubing inserts for this purpose. The tubing insert, usually made of metal, is pressed into the soft tubing, and supports the tubing wall so that it will not collapse as the ferrule is compressed. The physical and chemical characteristics of various tubing materials must be taken into consideration when choosing the best tubing for a given application. It is good practice to seek technical support from a tubing supplier when working on a new design.
Key factors include: pressure and temperature extremes, environmental conditions, vibration conditions, fluid compatibility, and minimum bend radius. In addition to these general considerations, there are several more specific factors to consider regarding compression fitting assemblies, such as:. PTFE tubing is a popular material choice for tubing because it is resistant to most chemicals, handles relatively high pressure, is low out-gassing, and is more flexible than metallic tubing.
This can cause leaks to develop over time, as the tubing wall begins to creep cold flow away from the ferrule. The cold flow issue is exacerbated when the tubing is exposed to high temperatures, and can occur even when fittings are properly installed and initially leak free. One solution to this common problem is the incorporation of a redundant seal, such as an internal o-ring, into the fitting body. This secondary sealing element makes a radial seal against the outside diameter of the tubing, independent of the seal created by the ferrule.
The way in which metal tubing is produced can have a significant effect on its performance with compression fittings. Tubing should be smooth and free of roughness or extrusion lines that can create a leak path past the ferrule.
Furthermore, tubing that has been stored in coils can often have an asymetrical diameter, preventing even compression. While an elastomeric seal can deform to match these slight variations, the metal-to-metal seal of a compression fitting is less forgiving. It is also important that the end of each section be squarely cut, to allow the tubing to sit symmetrically in the fitting body.
Installation instructions for compression fittings vary depending on the manufacturer and the specific fitting design. Care should be taken to follow the assembly procedures recommended by the manufacturer.
There are however, several common elements to the installation procedure for nearly all compression fittings:. Typically the procedure for tightening a compression fitting is specified using the rotation of the nut as the key metric, rather than torque. Torque, on the other hand, can vary greatly, depending on fitting and ferrule material, lubrication, degree of galling for stainless fittings , and other factors.
This does not hold true for compression fittings. Insufficient tightening of the compression nut will not deform the ferrule enough to create this contact, but over-tightening will deform the ferrule too much, creating a surface contact. A surface contact weakens the seal and often results in leaks.
As the nut is tightened, the compression ring is pressed into the seat, causing it to compress against the pipe and the compression nut, providing a watertight connection. Usually, that is. Though the primary advantage of compression fittings may seem to be in their ease of assembly, their real advantage is in their ease of disassembly! If you look throughout your home, you will see that the use of compression fittings is generally limited to appliances and fixtures that will Look under your bathroom vanities, behind your toilets, under your dishwasher or behind your refrigerator In fact, the now ubiquitous use of compression fittings in homes conveniently corresponds with the advent of do-it-yourself , user-friendly fixtures and appliances.
After all, if you want to sell faucets to folks with limited skills, you want to make their installation as painless as possible. Ergo, compression fittings! But compression fittings have a dark side, and may leak if not used properly. Here are my rules for the use of compression fittings. If you don't follow them, you may regret it! If you look critically at compression fittings, one thing is apparent However, they do a poor job preventing the pipe from turning within the fitting.
To visualize this, take the example of the connection for a refrigerator icemaker. Typically, a compression fitting is used to connect copper tubing to the icemaker.
Compression fittings are built from three pieces, creating a mechanical joint connection fitting which is widely used in plumbing systems to join tubing together.
Not sure what a ferrule is? It may actually be the most important component in a compression fitting. The ferrule is easily damaged and extreme care must be taken when installing it. However, installing a replacement if the ferrule gets damaged is very easy. A ferrule varies in material and shape but are most commonly found in the shape of a ring with bevelled or rounded edges. They are commonly made of brass or according to the pipe material. If the ferrules are identical on both ends then it does not matter which direction they are installed.
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