Restrictors integral

Figure 6.13 Flow restrictors of different design A, linear B, tapered C, integral and D, frit. On the right side is shown a modified high pressure cell for UV detection using open tubular columns.

If pi > P2, then air will flow from the proportional bellows through the integral restrictor and through the leak. As the rate of change of pressure in the bellows is proportional to this difference is pressure,... 

The rate of change of pressure in the integral bellows due to the leak is, however, half that due to flow through the integral restrictor, or ... 

Figure 11.19 384-parallel single-bead reactor with independent microreaction chambers and integrated flow restrictors. Typical bead diameter 1 mm. 

Thus, the pressure of the output to the valve P is the sum of Pi and the pressure produced by the wide-band proportional action contributed by the proportional bellows and the flapper-nozzle system (cf. equation 7.3). Note that for t > 0, P/ is no longer equal to P0 and thus equation 7.268 only strictly applies at t = 0. The value of 3 i (and consequently r/) depends upon the capacity C/B of the integral bellows and the the resistance to flow R/r through the integral restrictor. It is generally assumed that C/fi changes little and r/ is varied by adjusting R/r. 

Restrictors are required at the ends of SFC columns to maintain supercritical conditions throughout the column and to limit overall flow. Several options exist, with frit restrictors being the most popular, followed by integral and linear formats. The frit restrictor is... 

An important aspect for maintaining peak integrity using any split flow into a detector is the position of the restrictor tip relative to the detector source. Because SFC utilizes a gas under pressure, the rapid release of that pressure causes localized adiabatic cooling at the restrictor tip. On the other hand, at high temperatures. 

Figure 7.10. Separation of a broad molecular mass poly(ethylene glycol) trimethylsilyl ether sample using a frit restrictor (top) and integral restrictor (bottom). Column 10 m x 50 xm I.D. SB-biphenyl-30, film thickness 0.25 pm connected to the injector by a 1 m x 0.50 pm uncoated retention gap. Conditions Temperature 120°C pressure program 80 atm to 100 atm at 1.3 atm/min then 100 atm to 560 atm at 5 atm/min and held at 560 atm for 80 min mobile phase carbon dioxide. (From ref. [156]. Wiley-VCH).

Though SFC interfacing in an online fashion with an matrix assisted laser desorption ionization (MALDI) source has not yet been reported, the analysis of fractions from an SFC separation has been facilitated by the recent design of an online sample desorption device for MALDI.In this device, the end of the column is connected to an integral restrictor positioned over a spot of C18 sorbent saturated with an appropriate sample matrix such as a-cyano-4-hydroxycinnamic acid. The technique was applied to the separation of a silicone oil. MALDI-MS elucidated the polymer distributions corresponding to fractions deposited over a range of SFC retention times. 

The steam generator outlet nozzles are one piece forgings with an integral venturi type flow restrictor. The venturi section of the nozzle is designed to reduce the flow area by 70%. 

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