Hoses, flexible

Cutter-type samplers can be installed for low pressure pipelines and enclosed troughs. These samplers contain a movable cutter coimected to a flexible hose through which the sample is extracted. Such devices meet all three rules for good sampling they sample a moving stream, the sample is made... 

Vibration is both a cause of problems and an effect of equipment problems. The potential destructive force of an out-of-balance load has led to setting lower shutdown limits on the magnitude of vibration than other rotating equipment. Flexible connections for process and utility lines become a must so these vibration problems are not transmitted to connected equipment. Flexible hoses with liners having concentric convolutions (bellows type) avoid the sharp points inherent with spiral metallic liners. By avoiding the sharp point the liner is less likely to cut the exterior covering. 

Select appropriate constructional materials (flexible hoses)... 

Avoid flexible hoses where possible otherwise secure, shield and maintain Shield glass sections... 

Use jointing eompound or tape to eure leaks in oxygen equipment, e.g. at eylinder eonneetions. Cut off the supply of oxygen by nipping or kinking flexible hose when ehanging equipment. 

Plant and equipment generally portable tools flexible hoses lifting equipment pressure systems... 

The primary components of LVHV ventilation systems are the exhaust nozzles, flexible hose, fixed duct, air cleaner, and the exhauster and motor. Each of these is discussed below. Figures 10.23,10.27, and 10.28 illustrate LVHV nozzles. Figures 10.29 and 10.30 illustrate other system components and installations. 

Figure 10.29 shows a VS-Pritit illustrating a complete LVHV system (plan view) for a typical foundry application. This system connects five dustgenerating tools, each with its own exhaust nozzle. This figure also includes recommended nozzle volume flow rates and flexible hose inside diameters for several typical foundry-type operations. 

Deliveries to these installations are usually by road tanker. The tanker carries its own off-loading pump driven by the vehicle engine and the transfer is by a flexible hose which is connected to the receiving vessel by a gas-tight coupling. 

Three types of lines are used in fluid power systems pipe (rigid), tubing (semi-rigid), and hoses (flexible). A number of factors are considered when the type of line is selected for a particular application. These factors include the type of fluid, the required system pressure, and the location of the system. For example, heavy pipe might be used for a large, stationary system, but comparatively lightweight tubing must be used in mobile applications. Flexible hose is required in installations where units must be free to move relative to each other. 

Shock-resistant, flexible hose (Figure 40.32) assemblies are required to absorb the movements of mounted equipment under both normal operating conditions and extreme conditions. They are also used for their noiseattenuating properties and to connect moving parts of certain equipment. The two basic hose types are synthetic rubber and polytetrafluoroethylene (PTFE), such as DuPont s Teflon fluorocarbon resin. 

The size of a flexible hose is identified by the dash ( - ) number, which is the ID of the hose expressed in 16ths of an inch. For example, the ID of a —64 hose is 4 inches. For a few hose styles this is the nominal and not the true ID. 

As mentioned earlier, flexible hose is available in three pressure ranges low, medium and high. When replacing hoses, it is important to ensure that the replacement hose is a duplicate of the one removed in length, OD, material, type and contour. In selecting hose, several precautions must be observed. The selected hose must ... 

Flexible hose must not be twisted during installation. This will reduce the life of the hose and may cause the fittings to loosen. You can determine whether a hose is twisted by looking at the layline that runs along the length of the hose. If the layline does not spiral around the hose, the hose is not twisted. If the layline does spiral around the hose, the hose is twisted and must be untwisted. Flexible... 

The minimum bend radius for flexible hose varies according to the size and construction of the hose and the pressure under which the system operates. Current applicable technical publications contain tables and graphs showing the minimum bend radii for the different types of installations. Bends that are too sharp will reduce the bursting pressure of flexible hose considerably below its rated valve. 

Flexible hose should be installed so that it will be subjected to a minimum of flexing during operation. Support clamps are not necessary with short installations but for hose of considerable length (48 inches for example), clamps should be placed not more than 24 inches apart. Closer supports are desirable and in some cases may be required. 

A flexible hose must never be stretched tightly between two fittings. About 5 to 8 per cent of the total length must be allowed as slack to provide freedom of movement under pressure. When under pressure, flexible hose contracts in length and expands in diameter. Examples of correct and incorrect installations of flexible hose are illustrated in Figure 40.33. 

Some type of connector or fitting must be provided to attach the lines to the components of the system and to connect sections of line to each other. There are many different types of connectors and fittings provided for this purpose. The type of connector or fitting required for a specific system depends on several factors. One determining factor is the type of fluid line (pipe, tubing or flexible hose) used in the system. Other determing factors are the type of fluid medium and maximum operating... 

Figure 40.33 Correct and incorrect installation of flexible hose...

A great variety of PVC materials have been tested in the process thus far cable, cable trays, flooring material, window frames, artificial leather, packaging, pipes, flexible hoses, ring binders and roofing material. This indicates that the process is robust and can handle a broad range of PVC materials. In terms of chlorine content, there are no restrictions. With the completion of the pretreatment pilot plant, the contents of other plastics and metals may now be reduced significantly. 

Cut off the supply of oxygen by nipping or kinking flexible hose when changing equipment. 

The solvent reservoir is a storage container made of a saterial resistant to chemical attack by the mobile diase. In its simplest fora a glass jug, solvent bottle or Erlenmeyer flask with a cap and a flexible hose connection to the pump is adequate. The PTFE connecting hose is terminated on the solvent side with a 2 micrometer pore size filter to prevent suspended particle matter from reaching the pump. In more sophisticated instruments the solvent reservoir may also be Cjquipped for solvent degassing, as... 

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