Control erratic

The fix for the erratic reflux drum pressure problem was to provide for separate pressure control of the fractionator column and the reflux drum. A new pressure control valve was installed upstream of the condenser and the old condenser outlet control valve was removed. A hot gas bypass, designed for 20% vapor flow, was installed around the pressure control valve and condenser. A control valve was installed in the hot gas bypass line. The column pressure was then maintained by throttling the new control valve upstream of the condenser. The reflux drum pressure w as controlled by the hot gas bypass control valve and the psv saver working in split range. The new system is shown in the figure below. 

Problem A lean oil still had unstable control and erratic operation. 

If the unit pressure balance indicates that either the pressure gain in the standpipes is inadequate or the delta P across the slide valves is erratic, standpipe aeration and instrumentation should be examined. Redesigning the aeration systems or replacing the standpipes can gain valuable pressure drop. Proper instrumentation can include independent aeration flow to each tap, flow indicators/controllers on each, and differential pressure indicators between the taps. 

The cold gas recycle (CGR) ratio values (Figure 4) are metered values and are more consistent than the HGR and total gas recycle ratio values which were calculated from gas analyses. Although the calculated total recycle gas flow rate was erratic, catalyst bed temperatures were uniform and easily controlled by varying recycle rate and bed inlet tem-... 

Erratic meal hours or skipped meals may result in difficulty in controlling diabetes with tiiis drug. 

This example presents four analytical situations (a) good control, (b) sudden shift in accuracy - perhaps the calibration material has become contaminated, (c) a gradual shift in accuracy-perhaps a reagent has exceeded its expiry date, (d) very poor precision - perhaps an autosampler is working erratically. 

Most systems can be controlled manually or automatically. The modem trend is to automate the process as much as possible. One reason is that automatic controllers always respond the same way to changes, whereas men are erratic. Controllers may work for years with only minor maintenance, whereas a man fatigues easily. This means that while controllers may not produce a better product than an alert man, they can, in the long run, produce a more uniform product, with less waste and fewer accidents. 

Fig. 6.3. Laser control of high-voltage discharges, (a) Free discharge over 3 m, without laser filaments. Note the erratic path, (b) Straight discharge guided along laser filaments [25]...

The data in Tables 4 to 13 at 25°C plot nearly as vertical lines independent of the wt % NH3 in solution except for pure ammonia. At low concentrations the curves tend to deviate because of the ionization of NH3 and water. If the amount of ammonia in solution is approximately known, these curves can be used to estimate the moles of acid gas per mole of NH3 with fairly good accuracy. At 80°C the curves tend to slant more so the amount of ammonia in solution would have to be known more accurately before an estimate of the ratio of acid gas to ammonia could be made. Also we do not recommend the use of a pH probe at 80°C as a control indicator because the response of the probe is more erratic, and precise data are difficult to obtain. The use of an indicator probe at 25°C seems more logical because the output is more stable. 

The only significant difficulty in processing occured at carding where static electricity caused the web to behave erratically. The static was controlled by carding the cotton with a static bar in place under the web just as it exited the crush rolls. Processing and yarn quality results for the 3 cottons made into 19.7 mg/m yarns at 13000 rpm spindle speed are shown in Table X. Spinning quality results for the Mississippi and California cottons that were made into 14.8 mg/m yarn are shown in Table XI. 

Contrary to what is generally believed, the need for an effective control was always recognised, and indeed demanded, and there was a sort of control. However, it was patchy, very limited in its scope, erratic in its implementation and of little relevance to the drugs that were beginning, and were likely in the future, to appear in the market as a result of progress in pharmacology and medicinal chemistry. 

Absorption/Distrlbutlon - Phenytoin is slowly absorbed from the small intestine. Rate and extent of absorption varies and is dependent on the product formulation. Bioavailability may differ among products of different manufacturers. Administration IM results in precipitation of phenytoin at the injection site, resulting in slow and erratic absorption, which may continue for up to 5 days or more. Plasma protein binding is 87% to 93% and is lower in uremic patients and neonates. Volume of distribution averages 0.6 L/kg. Phenytoin s therapeutic plasma concentration is 10 to 20 mcg/mL, although many patients achieve complete seizure control at lower serum concentrations. 

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