How To Choose Hose Coulings?

Tina Tang
3 min readDec 16, 2021

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.

1. According to the type of fluid and temperature

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.

2. According to the corresponding use environment

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.

3. According to the structure of the automatic switching valve

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.

4. According to the type of threaded fitting

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.

We are a hose couplings supplier, please feel free to contact us if you need them.

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Tina Tang
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Shijiazhuang Donghuan malleable iron castings co., Ltd. established in 1986, which is an enterprise manufacturing malleable iron castings for more than 30 years