Rotary seal compound compounds

Rotary sealing rubber compounds, as opposed to static O ring compounds, should most preferably have 80 shore A to 90 shore A hardness. Soft rubber compounds, if used for manufacture of these seals, will tend to drag the rotating shaft, wear out and be heated up, causing failure. 

Rotary seal compound with high nitrile rubber content (Table 10.5)... 

Rotary seal compound with Nitrile/SBR blend (Table 10.7)... 

TABLE 10.7 Rotary seal compound with nitrile/SBR blend... 

TABLE 10.9 Alternative formulation for rotary seal compounds... 

Rotary seal compound organic cure (Table 10.18)... 

The rotary seal compound is sticky during mixing, but the O ring compound is not. The activator RCD 2098 is a zinc chloride/MBTS complex. Zinc diethyl dithiocarbamate and other activators containing zinc may also be used, but they are less effective. These polyurethanes have outstanding abrasion resistance, similar to neoprene in ozone and weather resistance, and comparable to nitrile rubbers in oil and fuel resistance. Heat aging is excellent up to 250°F (121°C), and the brittle point is —90°F (—68°C). 

Rotary seal compound (polyamine vulcanization system) (Table 10.25)... 

B. 1,4-Cyclohexanedione. The purified 2,5-dicarbethoxy-l,4-cyclohexanedione (170 g., 0.66 mole) (Note 5) and 170 ml. of water are placed in a glass liner (vented) of a steel pressure vessel of 1.5-1. capacity (fitted with a pressure-release valve). The vessel is sealed, heated as rapidly as possible to 185-195°, and kept at this temperature for 10-15 minutes (Note 6). The reaction vessel is immediately removed from the heater, placed in a large tub of ice water, and cooled to room temperature. The gas pressure then is carefully released. The resulting yellow to orange liquid is transferred to a distillation flask with the aid of a minimum volume of ethanol, and most of the water and ethanol is removed under reduced pressure by means of a rotary evaporator. The flask is attached to a short heated column fitted with a short air condenser. The remainder of the water and ethanol is removed under reduced pressure, and the 1,4-cyclohexanedione is distilled, b.p, 130-133° (20 mm.). The product solidifies to a white to pale-yellow solid, m.p. 77-79°, deld 60-66 g. (81-89% yield from 2,5-dicarbethoxy-l,4-cyclohexanedione). The compound may be conveniently recrystallized from carbon tetrachloride (7 ml. per gram of dione) the purified product is obtained as white plates, m.p. 77-79° (90% recovery). 

Single-stage oil-sealed rotary large water or vapor load may require use of refrigerated traps Single-stage or compound oil-sealed pump plus refrigerated traps, particularly at the lower pressure limit... 

Because of its elastic recovery properties, PTFE, a self-lubricating compound, is used in sealing and flexing applications such as sanitary seals, valve diaphragms, o-rings in mechanical seals, and seals and seats of stem and rotary valves such as ball valves. It is also commonly used as a liner or coating material for valves and pumps for the pharmaceutical industry. 

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