Nitrogen lines

The nitrogen line pressure is set to a level much less than the experimental pressure. With the nitrogen cylinder open, a check valve prevents the feed gas from getting into the nitrogen cylinder. When the surge check valve cuts off the synthesis gas feed, the unit becomes depressurized. Then pressure drops below the nitrogen pressure level, nitrogen flow will start and flush out the system. 

The unit shown on the next page in figure 4.4.1 is a somewhat simplified version of a tested, actual unit. The six gaseous feed components enter through check valves at a pressure regulated to about 4 atm higher pressure then experimental pressure, e.g., 22 atm. Six mass flow controllers set the flows and all but the nitrogen lines are secured with power to open solenoid valves (SV). 

In another incident the nitrogen flow was too small. The range of the rotameter in the nitrogen line was 0-60 L/min (0-2 fC/min) although 150 L/min (5 ft /min) was needed to keep the oxygen content at a safe level. 

A third incident occurred at a U.S. government facility. An employee connected his air mask onto a nitrogen line and immediately blacked out, fell, and hit his head. Fortunately, a stand-by man came to his assistance, and he recovered without serious injury. The compressed air and nitrogen lines used the same couplings, and the nitrogen lines, which should have been a distinctive color, had not been painted [22]. 

Once a vessel has been connected up to any process or service line, the full permit-to-work and entry procedure should be followed. In the present case, this should have started eight weeks before the incident. And the nitrogen line should have been disconnected or slip-plated where it entered the vessel. 

A suspension of 3.324 g (lO.Ommol) of (/ )-2-hydroxy-1,2,2-triphenylelhyl acetate in 40 mL of THF is stirred under nitrogen at — 78°C in a 250-mL. two-necked flask equipped with a three-way stopcock connected to a vacuum pump and a nitrogen line, septum, and magnetic stirring bar. After dropwise addition of the LDA solution, the mixture is stirred in an ice bath for 1 h to complete the double deprotonation. 

The reactor, a commercially supplied quartz photochemical reaction vessel, was fitted to meet the needs of this research (Figure 1). This included use of a Teflon-coated magnetic stirring bar in the reactor, a fiitted glass sparger, a nitrogen line used to cool the UV lany, and an injection port. Deionized water was distilled prior to use. 

The example of nitrogen lines in the spectrum of cobalamin points to the necessity of also writing out resonance conditions for the presence of ligand hyperfine interaction. In general we have ... 

If the chromium (II) chloride is prepared by the Holah-Fackler procedure from electrolytic chromium and hydrochloric acid, a three-necked round-bottomed flask may be used as a reaction vessel, and ammonia may be bubbled directly into the chromium(II) chloride solution using a T-joint in the nitrogen line. Bubbling of the ammonia through the liquid avoids the necessity for stirring. When the above procedure was used, it was necessary to centrifuge the final filtered solution at 2700 r.p.m. for 15 minutes in order to remove all the platinum catalyst. 

One way to solve the problem is to install an orifice plate in the nitrogen line, thus limiting the flow to the maximum of 0.5 kg/s. Determine the orifice diameter (in cm) required to achieve this flow. Assume a nitrogen source supply pressure of 15 bar absolute. The ambient temperature is 25°C and the ambient pressure is 1 atm. 

To 11.Og (12.3 mmol) of Wang resin (Note 1) in an oven-dried, solid-phase reaction flask (Note 2) equipped with an overhead stirrer and a nitrogen line attached to a bubbler was added 100 mL dichloromethane. The resultant slurry was allowed to stir for... 

Alternatively, the flask can be closed with a three-way stop-cock to maintain connections to a vacuum pump and to a nitrogen line. 

The first step of the chain extension reaction mechanism has been shown to b e etiolate formation, the by-product of which Is ethane gas. The nitrogen line should be attached to a large adapter to provide adequate venting of the gas. 

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