Cables for the transmission of telephones, telegrams, fax documents, television and radio programs, data and other electrical signals. It is made by twisting a pair of mutually insulated wires. The communication cable has the advantages of large communication capacity, high transmission stability, good confidentiality, less influence by natural conditions and external interference compared with the overhead open line.
Symmetrical cable
A communication circuit is composed of two symmetrically arranged wires. There are two types of high frequency and low frequency. The former has a maximum transmission frequency of up to 800 kHz, which corresponds to the opening of 180 telephones in a loop; the latter's maximum transmission frequency is generally less than 252 kHz, which corresponds to the opening of 60 telephones in a loop. The electromagnetic field of the symmetrical communication cable is in an open state, and the attenuation and loss of the loop are large at high frequencies, and mutual interference and external interference between the loops are large, and it is difficult to increase the transmission frequency and capacity.
Long-distance symmetrical communication cables consist of four-wire groups of different numbers and different insulation structures. The common form of the four-wire group is the star-shaped group, and some of the four-wire group is in the form of a double twisted pair. Insulation with paper tape insulation, paper - rope (paper and paper rope) insulation, polyethylene rope - belt insulation, polystyrene rope - belt insulation and foam polyethylene insulation and many other. The high-frequency long-distance symmetrical communication cable has a high transmission frequency, so the requirements for the structural performance of the cable are high. The rope-and-insulated star twist four-wire structure is generally used. Insulating materials commonly used polystyrene, polyethylene. Tape insulation is generally used for low-frequency symmetrical communication cables below 252 kHz.
The telephone cable is a symmetrical communication cable for a smaller area of ​​telephone connection in the city, suburbs, and industrial and mining companies, and is often called a local telephone cable. Its main feature is a large number of logarithms (up to several thousand pairs, usually hundreds or tens of pairs). Because the frequency of use is low and the communication distance is near, the cable diameter of the longer-distance communication cable is thin, typically 0.5 mm. The wire group structure of the telephone cable includes three types: twisted pair, star-type twisted group and double-pair twisted group. According to its core insulation and sheath materials can be divided into paper-insulated lead-sheathed cable, polyethylene insulation sheath cable, ointment filled waterproof cable, plastic cable. Two insulated wire conductors in a telephone cable are twisted together at a certain pitch to form an insulated wire pair. The color of the two insulated wire conductors in the wire pair is different (usually red and white) to distinguish them when wiring. The cable core structure of the telephone cable is generally divided into concentric type and unit type. The twisted pitches of adjacent pairs in the same layer should be different to reduce the interaction between calls. There is a pair of flags (blue and white, respectively) in each layer for easy identification when wiring. In 80 pairs or more of cables, there are often preparatory pairs to replace unqualified pairs. The unit cable is composed of 50 pairs or 100 pairs and the corresponding pair twisted to form a basic unit, and then several basic units are twisted into the cable core. After drying, the jacket is extruded to make a cable.
Overhead laying of the telephone cable is self-supporting, and the steel cable bears the weight of the entire cable. Since the 1960s, a waterproof cable has been developed that is filled with grease in plastic cables to prevent moisture and moisture.
In order to improve the moisture resistance and stability of communication cables, integrated cable sheaths have been widely used in the city's telephone cables since the 1970s. There are three basic types. 1Alpeth: Extruded a layer of polyethylene sheath outside the core of the cable, and then grounded the 0.2 mm corrugated aluminum strip longitudinally, filled with a polyisobutylene insulating compound and applied a layer of thermoplastic adhesive layer, and extruded the outermost layer of polyethylene. jacket. 2Stalpeth: Wrinkle aluminum strips are covered with a wrinkle steel strip outside, covered with a layer of thermoplastic material, and the outermost layer is extruded with a layer of polyethylene sheath. 3Lepeth: The core of the cable is covered with a polyethylene sheath, which is coated with a layer of viscous thermoplastic material. The outermost layer is extruded with a lead pipe.
Coaxial cable
A communication circuit (coaxial pairs) is formed by two mutually insulated concentric inner and outer conductors, and is formed by one or more coaxial pairs. Coaxial cables are mostly used as trunk lines for long-distance communications, and they provide multi-carrier communication or television programs. They are also used for efficient data transmission.
The coaxial conductors are completely concentric and there is no electromagnetic field outside the outer conductor. Therefore, the transmission signal attenuation and the mutual interference between the coaxial pairs are small, and the performance against external interference is also higher than that of the symmetrical cable. Its transmission frequency can reach 10 ~ 100 MHz or more. The model of the coaxial communication cable is divided according to the size of the coaxial pair, there are micro coaxial cable inner conductor diameter n/ outer conductor diameter D is 0.6mm/2mm, 0.9mm/3.2mm, etc.), small coaxial cable (n/D =1.2mm/4.4mm, etc.), medium coaxial cable (n/D = 2.6mm/9.5mm, etc.), large coaxial cable (n/D = 5mm/18mm, 11mm/41mm, etc.).
The inner conductor of the coaxial pair in the coaxial communication cable is copper, and the section is cylindrical and solid. In order to increase the mechanical strength (for example, when used as a submarine cable), there are also bimetal inner conductors using a steel core copper outer layer. Outer conductors are generally made of copper tape. Commonly used forms include corrugated, indented, and lock-type. The outer conductor needs good flexibility, high stability and simple processing technology. The insulation of the coaxial inner and outer conductors should have a low dielectric constant and a low dielectric loss, and should also have a certain mechanical strength to support the outer conductor so that it is concentric with the inner conductor. In order to eliminate inconsistency of coaxial concentricity and interference between coaxial pairs, the outer conductor must be covered with a shielding layer and then twisted into the cable. The shielding layer is mostly double wrapped steel strip.
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HIGH-MIDDLE-LOW PRESSURE UNION
Figure 602
With resilient nitrile-butadiene rubber seal ring, this figure is used for sealing and protecting the steel-to-steel match.
It is recommended for the connnection of mainfold and pipe and truck-mounted application and mud delivery. It may be used as pressureless seal union with butt weld Sch. 80.
Figure 1002
Resilient nitrile-butadience rubber seal ring is mounted.
It is recommended for cement filling, fracturing, acidizing, testing and choke and kill line. It is designed for high-pressure systems including truck-mounted system. Also, it may be used as pressureless seal union. Butt weld Sch. 160 or XXH is desired.
Figure 1003
With an spheric seat, the union allows a deviation by 7-1/2° from the center or angle adjustment with a total deviation capacity of 15°. In addition to the steel-to-steel match, the nitrile-butadiene rubber O-ring ensures air-tightness in connection at any deflected position.
Figure 1502
With replaceable resilient nitrile-butadiene rubber seal ring and robust wall thickness design, this figure is used in high-pressure system.
It is commended for comment filling, fracturing, acidizing, testing and chock and kill line. Also, it may be used in pressureless seal connection. Butt weld Sch. XXH is desired.
Figure 2002
For this union, only the 2in type is available with a replaceable resilient nitrile-butadiene rubber seal ring combined in the stainless steel liner tube, providing complete compression protection in application with extra high pressure. The design of detachable nut/segment ring/simplifies the removal of the nut from the piping.
Figure 2202
With fluoroelastomer seal ring, 15000PSI NSCWP and the heat-treated parts 100% subjected to hardness test, this model complies with National Association of Correction Engineers Standard MR-01-75 and American Petroleum Institute RP-14E.
This product is designed for application with acid gases. Green nuts and parts.
Specifications:
1. ISO 9001/ API Q1 / ISO14001 / OHSAS 18001 Certificate
2. Large stocks Timely delivery
3. Professional
4. Good after-sale service
High Pressure Union Series
High Pressure Union Series,High Pressure Union,Water Pressure Reducing Valve,High Pressure Hose
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