For sulfur hexafluoride

The 2003 ACGIH threshold limit valuetime-weighted average (TLV-TWA) for sulfur hexafluoride is lOOOppm (5970mg/m ). 

DISCUSSION. Figure 10.11 shows the separation of a group of gases from blood. The procedure described depends on complete equilibration between the gas and liquid in the syringe. The period to achieve equilibration depends on the gas, and can be as little as 1 min for acetone and as much as 30 min for sulfur hexafluoride. Linear calibration curves can be obtained when peak height is plotted against gas concentration for either the flame ionization or electron capture detector. The reproducibility (n = 10) for ethane gave a standard deviation of 23% of the mean concentration while it was 2.3% for halothane and 1.8% for ether. 

Calculate Z and V for sulfur hexafluoride at 100°C and 15 bar by the following equations (a) The truncated virial equation (3.33) with the following experimental values of virial coefficients ... 

Some atoms appear to exceed the octet rule. This behavior is observed only for those elements in Period 3 of the periodic table and beyond. To see how this arises, we will consider the Lewis structure for sulfur hexafluoride (SF6). The sum of the valence electrons for SF6 is... 

FIG. 2-30 Pressure-enthalpy diagram for sulfur hexafluoride (SFe). Properties computed with the NIST REFPROP Database, Version 7.0 (Lemmon, E. W, McLinden, M. O., and Huber, M. L., 2002, NIST Standard Reference Database 23, NIST Reference Fluid Thermodynamic and Transport Properties—REFPROP, Version 7.0, Standard Reference Data Program, National Institute of Standards and Technology), based on the equation of state of de Reuck, K. M., Craven, R.J.B., and Cole, W. A., Report on the Development of an Equation of State for Sulphur Hexafluoride, lUPAC Thermodynamic Tables Project Centre, London, 1991. 

Solved Problem 5.2 Write the formula for sulfur hexafluoride. 

To write the formula of a molecular compormd for which you are given the name, first write the symbols of each element in the order given in the name. Then add the appropriate subscript after each element that has two or more atoms present. Remember that the prefixes in the name teU how many atoms of each element are present. For example, the compound sulfur hexafluoride contains the elements sulfur and fluorine. Because the word sulfur has no prefix, it is understood that there is only one sulfur atom thus, the symbol S does not require a subscript. The prefix hexa tells you that six fluorine atoms are in the compound, so the subscript 6 must be added to the F. The formula for sulfur hexafluoride is SFg. Follow the rules for writing a formula for a molecular compound as you examine the formula shown in Figure 5.17. 

OTHER COMMENTS used in the manufacture of fluoro-chemicals and plastics used as one component of liquid rocket fuel and in chemical lasers chemical intermediate for sulfur hexafluoride, chlorine trifluoride, bromine trifluoride, uranium and molybdenum hexafluoride and oxygen difluoride. 

We can follow the same stepwise procedure we used above for sulfur hexafluoride. 

Dellis D, Samios J (2010) Molecular force field investigation for Sulfur Hexafluoride a computer simulatimi study. Fluid Phase Equilib 291 81-89... 

ACGIH recommends a Threshold Limit Value-Time-Weighted Average (TLV-TWA) of 1000 ppm (5970 mg/m ) for sulfur hexafluoride. The TLV-TWA is the time-weighted average concentration for a normal 8-hour workday and a 40-hour workweek, to which nearly all workers may be repeatedly exposed, day after day, without adverse effect [1]. 

OSHA lists an 8-hour Time-Weighted Average-Permissible Exposure Limit (TWA-PEL) of 1000 ppm (6000 mg/m ) for sulfur hexafluoride. TWA-PEL is the exposure limit that shall not be exceeded by the 8-hour TWA in any 8-hour work shift of a 40-hour workweek [2]. 

Most common gasket materials, including Teflon, neoprene, and natural rubber are suitable for sulfur hexafluoride service. 

The maximum filling density permitted for sulfur hexafluoride in cylinders is 120 percent (percent water capacity by weight). 

Cylinders that meet the following TC/DOT specifications are authorized for sulfur hexafluoride service 3A1000, 3AA1000,... 

Cylinders authorized for sulfur hexafluoride service must be requalified every 5 years with the exception that no retest is required for specification 3E cylinders. Furthermore, specification 3A and 3AA cylinders may be requalified every 10 years instead of every 5 years if they meet the requirements of 49 CFR 173.34 and CAN/CSA B339 [4, 7]. 

Material Safety Data Sheet for Sulfur Hexafluoride, Mathe-son Gas Products, Inc., Parsippany, NJ 07054. Material Safety Data Sheet for Sulfur Hexafluoride, Praxair, Inc., 39 Old Ridgebury Road, Danbury, CT 06817. Matheson Gas Data Book, 6th ed., 1980, Matheson Gas Products, Inc., Parsippany, NJ 07054. 

---