Gas Cell Essay Example | Topics and Well Written Essays - 750 words

Gas Cell - Essay Example Configured for gas sampling, the cell incorporates 2 valves, an inlet and an outlet, that enable flowing gas samples through the cell. In its solid and liquid vaporization configuration, the cell has an outlet needle valve from which a vacuum can be pulled and two (2) sample inlets. One inlet is a needle septa injection port on the top of the cell which is similar to the type used in gas chromatography. There is a second inlet in the form of a side port for inserting solid samples, which also doubles as the thermocouple port. Using the side port eliminates the need to recheck vacuum seals whenever the cell is opened to insert solid samples. The 250w heating jacket extends over the end of the cell so that both the cell body and the optics are heated, and allows operation at temperatures up to 1000K. Condensation on the optics is minimized by heating them to the same temperature as the sample chamber. A type J iron constantan thermocouple is provided with plugs which are compatible with the optional temperature controller. The cell body is type 304 stainless steel and an assortment of seals is provided - silicon rubber, viton and PTFE. Stainless Steel 304: SS 304 is the most versatile and the most ... It also has excellent low temperature properties and responds well to hardening by cold working. SS 304 is used in all industrial, commercial and domestic fields because of its good corrosion and heat resisting properties. Using SS304 is reducing the chances of failure of cell due to heating & creep. Creep Data Stress for a creep rate of 1% in 10 000 h. Temperature, oC 550 600 650 700 800 Temperature, K 823 873 923 973 1073 Stress, MPa 120 80 50 30 10 Environment Data/ Corrosion Rate The performance of SX 304 compared with other metals in various environments is shown in the following table. The corrosion rates are based on a 10 year exposure. Environment Corrosion Rate (m/year) SS 304 Mild Steel Rural 0.0025 5.8 Marine 0.0076 34.0 Marine Industrial 0.0076 46.2 So as compared to other metals stainless steel 304 is having very less corrosion rate, so this metal is best for the Gas cell. Stainless steel is also a preferred substrate because of its lower cost to fabricate into a mirror it requires multi-layer coatings, including gold as the primary reflective surface, which is expensive. Copper: Copper is a chemical element. Copper is malleable, ductile, excellent electrical conductor, non magnetic, resistant to corrosion, excellent heat transfer capacity, durable, & recyclable element. It is a ductile metal with excellent electrical conductivity and is rather soft in its pure state and has a pinkish luster which is. It finds extensive use as an electrical conductor, heat conductor, as a building material, and as a component of various alloys. Though copper has ductility property hence it can be drawn into thin wire. The ductility property of copper can reduce the chance of failure of cell due to

The Fallacy of the American Dream. The Reservation Cab Driver and Essay

The Fallacy of the American Dream. The Reservation Cab Driver and Mexicans Begin Jogging - Essay Example Of the 300 million American citizens, close to 50 million of them do not have basic health insurance. This is such a travesty in a country that is the sole superpower and the most prosperous. With the onset of the latest episode of economic recession, the unemployment rate has touched an alarming 10 percent. The main characters in the two poems have highly insecure jobs and barely scrap-by for a living. Living hand-to-mouth on a perennial basis, the attainment of American Dream is a distant and implausible reality for these people. The Reservation Cab Driver is a man of Native Indian origin, whose rickety Malibu 65 also doubles up as his house. His rights for a basic social security blanket are taken away by the same government agencies such as Bureau of Indian Affairs and HUD, that were meant to provide benefits. Living a nomadic life as a Reservation Cab Driver and working 24 hours a day he cannot yet earn a subsistence wage. His condition typifies the status of Native Indians as a whole. Once the rightful inhabitants of the vast American continent, the arrival of European colonizers put an end to their peaceful existence. Ever since, nearly the entire population of Native Indians have been wiped out, with few remaining descendants such as the Reservation Cab Driver still struggling for survival. (Alexie, 2011, p.173)