Pressure cylinders

Acetylene from calcium carbide can be advantageous in that calcium carbide may be shipped to the point of acetylene usage and acetylene generated on the spot. This avoids the necessity for low pressure, low pressure-drop gaseous acetylene pipelines, or high pressure cylinders for shipping acetylene. 

Chlorate candles ate quite stable. While normally hermetically sealed, these candles have been stored uncontained for as long as 20 years, and then operated successfully with no loss of oxygen output. Thus, they are well suited as emergency oxygen-generation systems (3). Chlorate candles also produce oxygen under pressure and, therefore, can be stored in or operated from pressurized cylinders. 

Creosote oils are by far the most widely used timber preservatives (see Wood). This use dates back to 1850. Eor the treatment of railway ties and marine pilings, the BetheU or fliU-ceU process is preferred. The timber to be treated is charged to a pressure cylinder, which is evacuated to extract the air from the wood ceUs. The cylinder is then filled with hot creosote and the pressure increased to 0.8—1 MPa (ca 8—10 atm) to force the oil into the ceUs. 

FIG. 10-95 Forged-steel single-acting high-pressure cylinder. 

FIG. 10-97 Typical packing arrangement, using metallic packing, for high-pressure cylinders. 

The synthesis gas comes premixed for the desired composition in a high pressure cylinder, e.g., DOT3AA6000 that has 1.5 ft = 42 liter volume. If this cylinder is charged to 380 atm and used down to 80 atm it holds as useful volume (380 - 80) 42 = 12,600 normal liter of synthesis gas. This is 562 g-mol. 

The most common material used in cylinder construction is cast iron for the larger, low-pressure cylinders and steel for the smaller, high pressure cylinders. In some cases, nodular or ductile iron can be used in lieu of cast iron. For hydrocarbon service, steel is most desirable, although not universally available. 

Pistons may be of segmented construction to permit the use of one-piece wear bands. One-piece wear bands are a requirement in API 618. Pistons have a problem in common with humans—a weight problem. Weight in a piston contributes directly to the compressor shaking forces and must be controlled. For this reason, aluminum pistons are often found in larger low pressure cylinders. Hollow pistons are used but can pose a hazard to maintenance personnel if not properly vented. If trapped, the gas will be released in an unpredictable and dangerous manner when the piston is dismantled. 

The piston is located at the end of the piston rod and acts as a movable barrier in the compressor cylinder. It is generally made from materials such as aluminum or cast iron and has a hollow center. Small-diameter high-pressure cylinders may be provided with a combined piston and rod machined from a single piece of bar stock. 

Tandem Compound high and low pressure cylinder on same centerline usually requires 80 psi or greater steam to be economical. 

Figure 12-2E. 250 psig working pressure cylinder used in refrigeration service. Auxiliary stuffing box for added sealing on shutdown. Manual fixed volume clearance pockets for capacity control. (Used by permission Bui. L-679-BIA, 1957. Dresser-Rand Company.)... 

Thus, in all compressors of two or more stages, the volumetric efficiency of the low-pressure cylinder determines the volumetric efficiency of the entire compressor (not recognizing packing leaks). ... 

Propane has a characteristic natural gas odour and is basically insoluble in water. It is a simple asphyxiant but at high concentrations has an anaesthetic effect. The TLV is 2500 ppm. It is usually shipped in low-pressure cylinders as liquefied gas under its own vapour pressure of ca 109 psig at 21°C. Its pressure/temperature profile is given in Figure 9.7. 

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