Pneumatic switches, operation

Each steam line has two containment isolation valves, one inside and one outside the containment barrier. The isolation valves are spring-loaded pneumatic piston-operated globe valves designed to fail closed on loss of pneumatic pressure or loss of power to the pilot valves. Each valve has an air accumulator to assist in the closiue of the valve upon loss of the air supply, electrical power to the pilot valves, and failure of the loaded spring. Each valve has an independent position switch initiating a signal into the reactor protection system scram trip circuit when the valve closes. 

Set timer (iii) (Figure 7.1) for 5 min. Open the split heater, move it forward on its travel and close it over the sample tube. Operate the push button for timer (iii). After the set time of 5 min the pilot valve, Mi, is triggered which operated the pneumatic switch valve, F, thus allowing helium carrier gas to flow around the external loop, H, through the sample tube and flushing the liberated volatile constituents on to the gas chromatographic column. The carrier gas remains routed around the external loop, H, until the re-set button is pressed. It is then diverted through the internal loop, G. 

Same equipment Eliminate multiple control locations, if possible can be controlled, Provide local hand/off/auto switch to prevent from different control room operation during field activities location (e.g., indication of status in control room pneumatic in field and digital in control room). ISA RP 60.3... 

The above produce a mechanical effect which can be used direcdy to operate an electric switch or modulate the pressure of an air jet (pneumatic system). 

Control can be exercised by the operator in the control roam on the well chokes and manifold divert valves (although this is normally handled by the HOC), start/atop of the oil shipping pumps, utility equipment, switching valves, gas plant feed valves, gas compressor start/stop and emergency shutdown of any production train or the entire GC. Since the closed loop process control is performed by local pneumatic instruments, all set point changes and controller troubleshooting must be accomplished locally. 

A schematic diagram of a heart-cut LC-LC system is depicted in Figure 5.4. The column switching technique was developed by employing two high-pressure four-way pneumatic valves inserted before and after the precolumn (39). The front-cut and the end-cut of the sample eluted from the first column were vented to waste. The valves were manipulated to transfer only the heart-cut of the analyte of interest to the analytical column. The detailed operational conditions for the four-step sequence of this system can be described as follows ... 

These systems (Fig. 7.56) can operate either electrically or pneumatically and they contain the necessary volumetric devices, the controls of which are either semiautomatic, interlocked or automatic, or a combination of these. With this type of equipment the level of admixture is allowed to rise in the sight-glass by the operation of a switch or valves until a correct level is reached. The valve is then opened to... 

The seven bullet tanks were equipped with a simple sprinkler system that could be switched on to spray individual tanks. Each bullet tank was equipped with safety relief valves and pneumatically operated plug valves for isolation of the inlet and outlet valves by remote control. The tanks rested on concrete saddles, but were not anchored. [10]... 

Back to the standard s content doors and covers giving access to the interior of enclosures containing remotely operated circuits with switching contacts which can be made or broken by non-manual influences (e.g. electrical, mechanical, magnetic, electromagnetic, pneumatic, hydraulic and others) shall... 

The regeneration of a micromembrane suppressor occurs in much the same way as for a hollow fiber suppressor. The regenerent is delivered pneumatically from the reservoir, since the required flow rate cannot be obtained simply via gravity feed. While a sulfuric acid concentration of c = 0.01 mol/L suffices for isocratic operation, a twofold regenerent concentration is recommended for gradient techniques. The flow rate should be adjusted to ensure a sufficiently low background conductivity when the maximum eluent conentration is reached. Maintaining these conditions, one can then switch to the initial eluent concentration. 

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