Recommendations on UZM's fluoroplastic hoses selections
Measurement and compliance
Depending on the country of origin different types of measurements and standards are applied. For example, DIN standard is used in Europe, ANSI in USA, GOST in Russia. Since this, in selecting pipe ends, fittings it is proposed to use reference materials, comparability tables of domestic and foreign measurement standards.
The marking is applied on the hose end to indicate the hose according to design documentation. Below is an example of PTFE hose marking (RFP series).
RFP 25-100-1,0 c/a
RFP — fluoroplastic (PTFE) smooth hose;
25 – nominal diameter of the hose;
100 - maximum operating pressure of a hose in kgf/cm2 (ATM) under normal operating conditions;
1,0 — nominal length of a hose assembly, m;
c / a – availability of special end fittings in accordance with Customer requirements. A full description of the end fittings is presented in the Customer's passport. Hoses without c/a marked abbreviation – are hoses without fittings with ends for welding
Conventional inner diameter of PTFE hose is the nominal parameter used in the description of pipeline systems, as a characteristic feature in the installation and fitting to each other parts of the pipeline. The nominal inner diameter is calculated in the design in such a way as to provide the required capacity of PTFE hose.
The operating pressure is the highest value of the pressure of the transported medium at which the specified operating mode is provided.
Depending on the value of this parameter, the type of fluoroplastic tube (thin-walled or thick-walled), as well as the number of braids (single or double) is selected.
Nominal length- is determined by the Customer, based on the requirements for the hoses installation.
When choosing PTFE hose, it is necessary to determine its optimal length for a particular installation case, since the usage of the hose that is too short or too long can lead to product’s damage at the place of fitting connection. The neutral areas near the fittings, that are not subject of bending during operation, must be taken into account as well in choosing the length of PTFE hoses.
It is possible to manufacture long hose assemblies by joining several hose parts, upon Customer’s request. Connection is carried out by welding with fittings for welding.
It should be noted that in the operation of solid fluoroplastic hoses with the length of over 1.8 meters, static electricity might come on by contact medium with the PTFE. It may lead to the damage of the flexible part by electricity, to the surface cracking and, as a result, to the loss of product tightness and failure. Based on the above, it is better to order PTFE hoses over 1.8 meters length with anti-static inner cover that will help to avoid premature failure.
End fitting is the end of PTFE hose serving to attach it to the parts embedded in the pipeline system.
Customer based on requirements of metal hose selecting the type of the end fittings. The most common type of end fitting for PTFE hose is union nut. See more on the end fittings page.
PTFE hoses of RFGf (corrugated fluoroplastic hose with lining) series with the lining fluoroplastic on the end fittings are produced for transporting particularly aggressive media. This allows to pass the medium through the hose without contacting with the metal. More about all series of PTFE hoses manufactured by Ufa Factory of Metal Hoses can be studied in the corresponding section of https://www.uzmr.ru/ptfe/.