Pumps pressure control

Multiplex wellhead high-pressure control pump valve... 

The mechanisms that control dmg deUvery from pumps may be classified as vapor-pressure, electromechanical, or elastomeric. The vapor-pressure controlled implantable system depends on the principle that at a given temperature, a Hquid ia equiUbrium with its vapor phase produces a constant pressure that is iadependent of the enclosing volume. The two-chamber system contains iafusate ia a flexible beUows-type reservoir and the Hquid power source ia a separate chamber (142). The vapor pressure compresses the dmg reservoir causiag dmg release at a constant rate. Dmg maybe added to the reservoir percutaneously via a septum, compressing the fluid vapor iato the Hquid state. 

Some toll processes lend themselves to test runs in the pre-startup phase. Actual materials for the toll may be used in the test or substitute materials, typically with low hazard potential, are often used to simulate the charging, reaction, and physical changes to be accomplished in the toll. Flow control, temperature control, pressure control, mixing and transferring efficiency can be measured. Mechanical integrity can be verified in regard to pumps, seals, vessels, heat exchangers, and safety devices. 

For positive displacement pumps, a bypass-type control valve should be furnished to set the primary lube system pressure. The valve should be able to maintain system pressure during pump startup and pump transfers, which includes relieving the capacity of one pump, while both are running. The valve should provide stable, constant pressure during these transients. Flow turndown of 8 to 1 is not unusual. Multiple valves in parallel should be used if a single valve is not suitable. The valve should be sized to operate between 10 and 90% of the flow coefficient (Cv). Additional pressure control valves should be furnished as required to pro ide any of the intermediate pressure levels. 

Lubrication of cuuplitigs, Lubrication pumps. uid drivers, 309 Lubrication systems check valves, I commissioning, 462, 4ti coolers, 315 degassing drum, 322 filters, 316 gear box, 328 oil flooded helical, 109 overall system review, 1 overhead tanks, 319 piping, 322 pressure control valves, 313... 

FV - Flow Control Valve T - Tank P - Pump PV - Pressure Control Valve RV - Relief Valve V - Valve 1 - 1 inch size P - Pressure T - Temperature L - Level F - Flow I - Indicator C - Controller A - Alarm H - High. L - Low... 

Figure A8.14 Closed column reactor for the production of L-alanine. 1) reactor 2) plunger pump 3) pressure control valve 4) reservoir 5) substrate tank 6) pressure gauge 7) safety valve 8) heat exchanger.

Use of an infuson pump or controller still requires nursing supervision and frequent monitoring of the IV infusion. Infiltration can progress rapidly because the increased pressure will not s/ow the infuson until considerable edema has occurred. Therefore, it is important to monitor frequently for signs of infiltration, such as edema or redness at the site. Careful monitoring of the pump or controller is also necessary to make sure the flow rate is correct. 

Fig. 2.9 Schematic diagram of experimental set-up 1 inlet tank, 2 pump, 3 control valve, 4 temperature and pressure measurement ports, 5 sample of porous medium, 6 top of test section, 7 housing, 8 copper rod, 9 heater, 10 insulation, 11 exit tank, 12 electronic scales. Reprinted from Hetsroni et al. (2006a) with permission...

Flash vaporization is another simple delivery design, where the liquid is metered into a vessel heated above its boiling point (at the prevailing pressure). Controlled metering of the liquid into the vaporizer can be accomplished by a peristaltic pump or similar devices. A typical vaporizer to supply TiC is shown in Fig. 5.3. 

A fixed-bed reactor system was employed (Figure 32.2). Each of the two reactors was charged with 38 cc of Amberlyst BD20 catalyst. Sample ports located at the exit of each reactor enabled increased acquisition of residence time data. Pressure was maintained by a back pressure control valve to maintain methanol in the liquid phase. After charging, the 1st and then 2nd reactors were connected to the pumps and filled with the reaction mixture while vapor was released from each through the top vent valve. Once each reactor was filled with liquid and emptied of vapor, the pressure regulator was connected to the output and both reactors were immersed into the water bath. 

A schematic diagram of a chromatograph for SFC is shown in Figure 6.10. In general, the instrument components are a hybrid of components developed for gas and liquid chromatography that have been subsequently modified for use with supercritical fluids. Thus, the. fluid delivery system is a pump modified for pressure control and the injection system a rotary valve similar to components used in liquid chromatography. The column oven and... 

The basic SFC system comprises a mobile phase delivery system, an injector (as in HPLC), oven, restrictor, detector and a control/data system. In SFC the mobile phase is supplied to the LC pump where the pressure of the fluid is raised above the critical pressure. Pressure control is the primary variable in SFC. In SFC temperature is also important, but more as a supplementary parameter to pressure programming. Samples are introduced into the fluid stream via an LC injection valve and separated on a column placed in a GC oven thermostatted above the critical temperature of the mobile phase. A postcolumn restrictor ensures that the fluid is maintained above its critical pressure throughout the separation process. Detectors positioned either before or after the postcolumn restrictor monitor analytes eluting from the column. The key feature differentiating SFC from conventional techniques is the use of the significantly elevated pressure at the column outlet. This allows not only to use mobile phases that are either impossible or impractical under conventional LC and GC conditions but also to use more ordinary... 

Implementation of SFC has initially been hampered by instrumental problems, such as back-pressure regulation, need for syringe pumps, consistent flow-rates, pressure and density gradient control, modifier gradient elution, small volume injection (nL), poor reproducibility of injection, and miniaturised detection. These difficulties, which limited sensitivity, precision or reproducibility in industrial applications, were eventually overcome. Because instrumentation for SFC is quite complex and expensive, the technique is still not widely accepted. At the present time few SFC instrument manufacturers are active. Berger and Wilson [239] have described packed SFC instrumentation equipped with FID, UV/VIS and NPD, which can also be employed for open-tubular SFC in a pressure-control mode. Column technology has been largely borrowed from GC (for the open-tubular format) or from HPLC (for the packed format). Open-tubular coated capillaries (50-100 irn i.d.), packed capillaries (100-500 p,m i.d.), and packed columns (1 -4.6 mm i.d.) have been used for SFC (Table 4.27). 

Most centrifugal pumps are controlled by throttling the flow with a valve on the pump discharge, see Section 5.8.3. This varies the dynamic pressure loss, and so the position of the operating point on the pump characteristic curve. 

The best approach is of course a fully UHV compatible set-up with an electrochemical preparation chamber which fulfills UHV standards with respect to cleanliness and pressure control. The electrochemical chamber is filled with argon at atmospheric pressure only during the electrochemical treatment. Afterwards the chamber can be pumped down directly. Such a system was first described by O Grady [39] and was also used by Ross [40], Hubbard [41], Gerischer [42], and Streblow [36]. 

The understanding that the computers controlling the equipment might possess could be contained within a kinetic and thermodynamic model that encapsulates the detailed chemistry of the process. This would include a description of all the reactions that might be expected to occur under the conditions achievable in the plant, together with a list of the relevant rate constants and activation energies for each reaction. In addition, process variables, such as maximum flow rates or pump pressures that are needed for a full description of the behavior of the system under all feasible conditions, would be provided. 

Vacuum chamber with tempered shelves 2, container with probe 3, lift for shelves 4, condenser 5, lockgate 6, balance in the lock 7, vacuum pump for the lock 8, glove box 9, Karl-Fischer measuring system 10, pressure controlled vacuum pump 11, manipulator 12, tempered medium (Fig. 1 from [3.30]). 

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