AH Compressor Coupling Hose-end Type in US
The market is flooded with hose couplings, how do you choose the right hose couplings to fit your hose? Here are some reference suggestions that can help you.
Different kinds of fluids and body material, sealing material, need to be equipped with different metal hose fittings. If it is air, metal fittings made of steel are recommended; if it is water, metal fittings made of brass or stainless steel are recommended. Therefore, the purchase of metal hose fittings should consider the chemical composition of the fluid, temperature, and pressure, etc., and the consistency of the pipe fittings. In order to avoid the erosion of mineral oil and synthetic fluid, most of the pipe fittings are plated. If there is a rubber seal as the parts of the pipe fittings, it is necessary to ensure that the seal material is compatible with the fluid.
Including the use of environmental humidity conditions, the condition of the dust and whether it is easy to corrode, and other factors to consider the selection of the type of joint, the body material, sealing material. If the metal hose joint is exposed to a chemically corrosive environment, such as saltwater or acidic gas, only stainless steel joints can be used according to regulations.
The structure of the valve usually has a two-way switch type, one-way switch type, and two-way open type. In the purchase of metal hose joints, it is necessary to find out in advance which type it is. In addition to the two-way switch type, there will be fluid flowing out of the piping when it is separated, so it is necessary to select a fitting of the valve structure suitable for piping purposes.
●NPT stands for National (American) Pipe Thread, which is an American-made tapered pipe thread used for sealing. NPT is the American standard 60 degrees tapered pipe thread used in North America. The national standard can be found in GB/T12716-1991.
●PT is the abbreviation of Pipe Thread, which is a 55-degree tapered pipe thread for sealing and belongs to the Whitworth thread family, mostly used in Europe and Commonwealth countries. Commonly used in the water and gas pipe industry, the taper is 1:16. The national standard can be found in GB/T7306-2000.
●G is a 55-degree non-threaded sealing pipe thread, which belongs to the Wheatstone thread family. The mark G stands for the cylindrical thread. The national standard can be found in GB/T7307-2001. G is the generic name of pipe thread (Guan), and the division of 55 and 60 degrees is functional, commonly known as the pipe circle. This means that the thread is machined from a cylindrical surface.
Tip: The metric thread is expressed in terms of pitch, while the American and British threads are expressed in terms of the number of threads per inch, which is the biggest difference between them.
Hoses, as well as fittings, come in many different types and materials. Importantly, the material used for the hydraulic hose fitting defines its properties. Most common fittings are made of plastic, steel, stainless steel, or brass.
Plastic fittings generally are considered more resistant to the corrosion but are weaker and less durable. Therefore, they are the least popular choice when it comes to hydraulic applications despite their low price. Due to the high-pressure ratings, metal fittings are a better fit.
Steel fittings come as a mix of iron with some other metals to make them more durable and improve the resistance to the heat. For example, carbon steel fittings made of the mixture of iron and carbon can withstand the temperatures from -65°F to 500°F.
Stainless steel fittings are used when the temperature range required for the job is -425°F to 1200°F. They are an excellent choice for highly corrosive environments. Usually, they are rated up to 10,000 psi. Some of the stainless steel fittings with special designs can be rated up to 20,000 psi. However, the high price makes them less affordable, so other alternatives are usually considered.
Brass fittings are less strong and durable than stainless steel. They can provide a leak-free operation and meet SAE, ISO, DIN, DOT, and JIS standards. Brass fittings temperature range is -65°F to 400°F. They accommodate pressure up to 3000 psi, but lower pressure ranges are usually recommended.
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