Nitrogen flow rate

Set the chromatograph oven to 75 °C and the carrier gas (pure nitrogen) flow rate to 40-45mL min-1. 

Nitrogen flow rate N2 make-up gas flow rate Attenuation Range... 

Fig. 2.40.2. Chamber pressure and nitrogen flow rate as a function of drying time. 1 main drying, 2 chamber pressure, 3 nitrogen flow, 4 secondary drying (Fig. 4 from [2.32]).

To the flask are added 13.4 g. (0.58 mole) of clean sodium and 200 ml. of absolute toluene. The Vibromischer stirrer is activated, the toluene heated to reflux, and the agitation continued at this temperature until all the sodium is pulverized into a very fine sand. The agitation is ceased, and the solution is allowed to cool to room temperature. The nitrogen flow rate is increased, the Vibromischer stirrer is replaced with a conventional sealed mechanical stirrer with a Teflon blade, and a solution of 85 g. (0.6 mole) of 2-carbomethoxycyclopentanone (Note 2) in 450 ml. of absolute benzene is placed in the addition funnel. 

Fig. 8. Optimal nitrogen flow rate for variable V. Reprinted with permission from Comp. Chem. Eng., 14, No. 10, 1083-1100, S. Vasantharajan and L. T. Biegler, Simultaneous Optimization of Differential/Algebraic Systems with Error Criterion Adjustment, Copyright 1990, Pergamon Press PLC.

The reaction is exothermic and occurs at ordinary temperatures. The reaction may be controlled by adjusting temperature and nitrogen flow rate. The reaction proceeds rapidly when the metal is heated in nitrogen. 

In order to see the magnitude of the variables, consider the aeration of a cylindrical tank lm deep and 1 m diameter. Nitrogen is sparged to desorb oxygen from the liquid. Water flows continuously across the tank at a rate of 1 L/s. The nitrogen flow-rate is 0.061 kg/s, and the temperature is 20°C. The results of the outlined calculation of a suitable sparger ring, are as follows ... 

Determine the time and nitrogen flow rate so that breakthrough (no more retention for a given substance) of the trap does not occur. Do this by attaching a second trap in series and analyzing this trap. For aroma compounds, smell the end of the trap to detect odor-active compound leakage. Even if the vessel is heated, the trap should be kept at room temperature. 

V.p.c. analysis shows contamination by less than 3% of carvone. The checkers used a 1 m. by 4 mm. glass column packed with 5% PEG 6000 on Chromosorb W (60/80 mesh). The retention times were 3.7 minutes and 2.75 minutes for carvone and dihydrocarvone, respectively, at 100° with a nitrogen flow rate of 90 ml. per minute. 

Note. (1) Gas-liquid chromatography analysis using 10 per cent Silicone oil column (1.5 m) at 40°C with a nitrogen flow rate of 40ml per minute gives tR 1.18 minutes. 

Gas-liquid chromatography analysis using a 1.5 m S.E. 52 chromatographic column, at 120 °C with a nitrogen flow rate of 45ml/minute, gives retention times for phenylacetylene and tu-bromophenylacetylene of 2.16 and 0.76 minutes respectively. 

Diglyme, which has b.p. 162 °C at 760mmHg, must be completely removed from the ether extract - otherwise it will contaminate the product. Its presence in the extract may be conveniently checked by g.l.c., using a 1.5-m column of 10 per cent Silicone oil on Chromosorb W held at 100 °C, with a nitrogen flow rate of 40ml/minute, tR 3.2 minutes. 

Check the purity by g.l.c. on a 10 per cent Silicone oil column at 100 °C, nitrogen flow rate 40 ml per minute. The retention time is 1.42 minutes (cf. hexan-l-ol, 1.96 minutes). 

---