Cylinders contents

Precautions also have to be instituted to protect against the inherent properties of the cylinder contents, e.g. toxic, corrosive, flammable (refer to Table 8.1). Most gases are denser than air common exceptions include acetylene, ammonia, helium, hydrogen and methane. Even these may on escape be much cooler than ambient air and therefore slump initially. Eventually the gas will rise and accumulate at high levels unless ventilated. Hydrogen and acetylene can form explosive atmospheres in this way. 

The graphic below describes the permanent, stamped markings that are used on high-pressure gas cyhnders commonly found in analytical laboratories. Note that individual jurisdictions and institutions have requirements for marking the cylinder contents as well. These requirements are in addition to the stamped markings, which pertain to the cyhnder itself rather than to the hll contents. 

After evacuation, standard vacuum techniques are used to measure and condense equimolar amounts (20 mmoles each) of carbonyl fluoride and oxygen difluoride into the cylinder. The cylinder should be equipped with an explosion rupture assembly and should be in a shielded location before it is allowed to warm up. The valve is then closed, and the cylinder and its contents are allowed to warm to room temperature and remain at that temperature for 5 days. After this time, the cylinder contents are passed through a trap kept at approximately — 140°C. (melting Skelly-Solve F or methylcyclopentane). 

What the phase diagram means and what can be done with it are illustrated by a hypothetical experiment in which pure water is placed in a leakproof evacuated cylinder fitted with a movable piston, as shown in the diagram below. Heat can be added to or withdrawn from the cylinder, so that the temperature in the chamber can be adjusted to any desired value, and the absolute pressure of the cylinder contents [which equals F + W)/ A, where W is the weight of the piston] can similarly be adjusted by varying the force F on the piston. 

Plan We have to find the volume of the galena from the change in volume of the cylinder contents. The volume of galena in mL is the difference in the known volumes before and after adding it. The units mL and cm represent identical volumes, so the volume of the galena in mL equals the volume in cm . We construct a conversion factor to convert the volume from mL to L. The calculation steps are shown in the roadmap. 

The purity of the SCF is an important consideration in the planning of a synthesis. Low concentrations of impurities can have noticeable effects on the volumetric and phase behavior of SCFs. For example, helium can be present in commercial CO2 because it is sometimes added as a head-gas to ensure nearly-complete delivery of the cylinder contents and this has been found to affect the use of SCCO2 as a solvent for analytical and prepeu-ative purposes [51-53]. The He head-gas is unnecessary if a cooled pump is used for CO2 delivery. 

Example 19-1 Suppose a gas cylinder contents has 22001b/in. (gauge) at 70°F. After exposure to direct sun, the temperature increases to 180°F. What is the pressure after exposure ... 

Fig. 3-2. Schematic example of CGA shoulder decal used to identify cylinder contents in accordance with Appendix A of CGA C-7-1992, Guide to the Preparation of Precautionary Labeling and Marking of Compressed Gas Containers [9].

The gasket is the part that provides the proper seal to prevent leakage of the cylinder contents past the rupture disk assembly and is constructed of metallic or nonmetal lie materials. 

Type CG-4 and CG-S (combination rupture disk/fusible plug). A combination rupture disk/fusible plug pressure relief device requires both temperature and pressure in that order for it to operate and therefore provides for maximum retention of the cylinder contents. Sufficient heat is required to first melt out the fusible metal, after which the device will afford the same protection as the CG-1 rupture disk device. 

The cylinder content must be identified by labeling. Inappropriate, obsolete, illegible, or... 

Residual cylinder content should be confirmed and recovered or disposed of The method of disposal of residual content will de-... 

Residual cylinder content should be confirmed and recovered, or disposed of. The method of disposal of residual content will depend on the product and applicable environmental regulations. An appropriate disposal system should be available. Venting should be directed outside the building, away from building air intakes. Residual gas or liquid in all medical cylinders must be vented. Each vented cylinder is evacuated to a minimum vacuum of approximately 25 inches (635 mm) of mercury (Hg). The vacuum valve and each cylinder valve are closed, and the pump is then shut down. 

It is absolutely essential that the cylinder contents be identified before disposing of the cylinder. Content determination may be obtained through knowledge of the cylinder s origin and use, labeling and valve configuration. Cylinders with unknown contents require analysis to determine their contents. 

Sampling and analysis of the contents provide the most reliable information for proper management of problem cylinders with unknown contents. Any inconsistency, question or lack of knowledge about the cylinder contents is cause for requiring positive identification through sample and analysis. Properly trained personnel must conduct these operations. 

Equipment used for sampling cylinder contents should be rated for the service pressure stamped on the cylinder, with suitable safety factors applied for potentially overpressurized containers. All components of the system should be cleaned and suitable for oxygen service as a minimum standard. Passivation (the rendering of a surface less reactive to strong oxidizers) of the system may be required for stronger oxidizers (for example, fluorine compounds). 

Liquid contents at low pressure. Laboratory analysis of a vapor phase sample may not indicate actual cylinder contents. Both the liquid and vapor phases should be sampled. 

If a cylinder valve is damaged in a way that prevents the discharge of the cylinder contents in a normal manner, it may be possible to release the pressure in the cylinder through the pressure relief device. However, only qualified personnel familiar with gas cylinders and their pressure relief devices should attempt this procedure. It should not be attempted where the gas content may be noxious. Further, it should not be attempted without PPE or venting procedures. 

Before proceeding with the disposition of cylinder contents, the label should be read to determine if the cylinder contents are toxic or an ozone depleting substance. These substances require special care and handling. The cylinder contents should be treated as a toxic substance... 

Prior to decommissioning, cylinder contents shall be verified and removed and the cylinder purged with an inert gas. The decommissioning process should destroy the cylinder, rendering it unusable. No liquid or solid residues should be present. All materials that may have been absorbed into, or deposited onto the walls of the cylinder should be removed prior to disposition of the cylinder if they present a health or environmental hazard. 

Remove cylinder contents and purge the cylinder with an inert gas. 

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