Interlock, interlocking power

Depending on the degree of potential catastrophe, there usually is more than one safety interlock for a potential catastrophic event. Each of these safety interlocks including the sensor/transmitter, control function, and final control element are usually independent of the other safety interlocks for the same event. For maximum protection, each sensor for the same event should be unique to eliminate the potential of a common failure. The safety interlock must be fail-safe. This means that any loss of interlock power—electricity, air, hydraulics, etc.— loss of signal, must produce the same action as the safety interlock produces when it is activated (tripped). 

The next step is to apply a number of loss control credit factors such as process control (emergency power, cooling, explosion control, emergency shutdown, computer control, inert gas, operating procedures, reactive chemical reviews), material isolation (remote control valves, blowdown, drainage, interlocks) and fire protection (leak detection, buried tanks, fire water supply, sprinkler systems, water curtains, foam, cable protection). The credit factors are combined and appHed to the fire and explosion index value to result in a net index. 

Lead bricks are generahy used as temporary shields for radiation sources at nuclear power stations, research institutes, hospitals, and fuel reprocessing plants. Plat, rectangular bricks requite a double layer with staggered seams whereas the interlocking bricks requite only one course. Lead shot can be poured into inaccessible areas like a Hquid. 

Interlock pressure or pump power to shutoff pump... 

Interlock agitator power consumption to cutoff feed of reactants or catalyst or activate emergency cooling... 

For instrument modules, relay and control modules or control panels or all power modules, where an interlock with the door is not possible or is not provided, a proper shroud or shutter must be provided on all exposed live parts rated above 240 V. 

Test This is the position of the trolley when the power contacts are isolated but the control circuit is still connected, because it is tapped directly from Ihe auxiliary bus. This condition is essential to facilitate testing of control circuits with functional interlocks, without energizing the connected lotid. Isolation This is the position of the trolley when the power and the control circuits are both isolated. Depending upon the site requirements, sometimes the control circuit may be required to be still energized for some test requirements. 

Safety Considerations. High-power lasers raise a number of safety issues. There are the flammability and the toxicity of dye solutions. Most importantly, the eye hazards of laser radiation require careful shielding of the beam, and interlocks that restrict access to the laser room and to the dome. The laser could also dazzle aircraft pilots if they look directly down the beam. It is therefore necessary to close a shutter in the beam when a plane comes too close, either manually by human spotters, or automatically by use of radar, thermal IR or CCD cameras. Care must also be taken to avoid hitting overhead satellites in the case of pulsed or high power laser systems. 

The process unit has many loss control features. The plant has a diesel emergency power generator with an emergency cooling system. The plant is also under computer control with emergency shutdown based on redundant inputs. Vacuum is always broken with nitrogen. The process has complete, written, and up-to-date operating instructions. A reactive chemicals review was completed recently. The process has several interlocks to prevent polymerization. 

Safety mnst be the first consideration of any process analytical installation. Electrical and weather enclosures and safe instrnment-process interfaces are expected for any process spectroscopy installation. The presence of a powerfnl laser, however, is nniqne to process Raman instruments and mnst be addressed due to its potential to injnre someone. Eye and skin injnries are the most common resnlts of improper laser exposure. Fortunately, being safe also is easy. Becanse so many people have seen pictnres of large industrial cutting lasers in operation, this is often what operations personnel erroneonsly first envision when a laser installation is discnssed. However, modem instmments nse small footprint, comparatively low power lasers, safely isolated in a variety of enclosures and armed with various interlocks to prevent accidental exposnre to the beam. 

These lamps are radio frequency (RF) powered, and can be easily controlled and switched. The power supply includes all electrical controls, interlocks, and the water cooling supply system. A complete system is shown schematically in Figure 3.4. 

Several examples of catenanes and rotaxanes have been constructed and investigated on solid surfaces.1 la,d f 12 13 26 If the interlocked molecular components contain electroactive units and the surface is that of an electrode, electrochemical techniques represent a powerful tool to study the behavior of the surface-immobilized ensemble. Catenanes and rotaxanes are usually deposited on solid surfaces by employing the Langmuir-Blodgett technique27 or the self-assembled monolayer (SAM) approach.28 The molecular components can either be already interlocked prior to attachment to the surface or become so in consequence of surface immobilization in the latter setting, the solid surface plays the dual role of a stopper and an interface (electrode). In most instances, the investigated compounds are deposited on macroscopic surfaces, such as those of metal or semiconductor electrodes 26 less common is the case of systems anchored on nanocrystals.29... 

Summing up, it can be said that interwoven and interlocked molecules open up enormous possibilities not only to chemists but also to interdisciplinary researchers. Non-ionic templated syntheses and the newly established non-template strategy are powerful tools for further rapid and unprecedented developments in this field. 

As as been pointed out in Boxes 3-C and 17-C, the use of 13C and other isotopic tracers together with NMR and mass spectroscopy have provided powerful tools for understanding the complex interrelationships among the various interlocking pathways of metabolism. In Box 17-C the application of 13C NMR to the... 

Three types of mixer are recognized, plus a miniature mixer which would provide just enough compound for a curemeter test and one sheet. Mixers types A] and A2 and the miniature device have non-interlocking (tangential) rotors whilst type B has interlocking rotors. Dimensions of the larger mixers are specified fairly precisely, including new and worn rotor clearances, and they are required to have temperature control, a system to record power or torque and a timer. The miniature mixer is only specified in terms of capacity, rotor speed and friction ratio but is required to control of temperature, indication of power and a timer. 

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