Ultraviolet sensor

All of the ionizing air systems at Longhorn are located in areas where ultraviolet sensors are used in conjunction with deluge systems for fire protection. Care must be taken to shield the ultraviolet detectors from the ion generating corona source. The systems used at Longhorn are individually shielded with PVC tubing or with hoods. 

The fire protection system consists not only of a deluge system activated by the ultraviolet sensors, but also of fusible link type fire systems. The deluge system has a trip mechanism from mercury checks activated by heat-activated-devices, a manual release on the deluge valve, a pneumatic remote trip station, and an electrical push button along with the electrical trip mechanism from the U/V detectors. The remote trip stations are located by escape routes so it is possible for the operator to trip the systems as he exits the building without exposing himself to further danger. 

The third major component would be the controller that takes the signal from the ultraviolet sensor and amplifies it to a power voltage that operates the valve. The controller was constructed of standard electrical components that were on hand. In addition to opening the valve, it would shut off the power to the machines to prevent additional damage and would also sound an alarm. 

Before the third series of tests was made, additional research was required to find or develop an ultra-fast opening valve. This was the only major component that could be replaced to further reduce the response time. Information from Detector Electronics Corporation introduced us to a valve manufactured by Grinnell, called the Primac valve, which seemed to fit the bill. The valve uses a primer detonating device with redundant detonators to blow the valve open. The same electrical signal initiated by the ultraviolet sensor could now be used to actuate the detonators, thus further reducing lost motion. 

Day Zimmermann has installed approximately 90 ultraviolet sensor deluge systems in the Lone Star and Kansas Army Ammunition Plants. The Primac valve is only used in the black powder operation because of its higher cost. All other materials use the system as described in the second series of tests and is considered highly effective. 

Some ceramics are transparent to light of specific frequencies. These optical ceramics are used as windows for infrared and ultraviolet sensors and in radar installations. However, optical ceramics are not as widely used as glass materials in applications in which visible light must be transmitted. An electro-optic ceramic such as lead lanthanum zirconate titanate is a material whose ability to transmit light is altered by an applied voltage. These electro-optic materials are used in color filters and protective goggles, as well as in memory-storage devices. 

Technology has been introduced for on-line estimation of the kappa number based on absorption of ultraviolet light (35). This breakthrough ia optical sensor technology permits closed-loop feedback control of digesters from on-line measurement of the kappa number. 

Luminescence can be defined as the emission of light (intended in the broader sense of ultraviolet, visible, or near infrared radiation) by electronic excited states of atoms or molecules. Luminescence is an important phenomenon from a basic viewpoint (e.g., for monitoring excited state behavior) [1] as well as for applications (lasers, displays, sensors, etc.) [2,3]. 

As an example of application of semiconductor sensors for this purpose, we consider photolysis of simplest olefines (ethylene, propylene, acetylene, etc.) occurring in the range of vacuum ultraviolet. It is well-known (e.g., see [11]) that photolysis of ethylene may result in detachment of either hydrogen molecules (detached in one act) or hydrogen atoms. Hydrogen atoms subsequently associate into molecules or interact with ethylene molecules. In what follows, we consider how this problem can be solved with the help of sensors. 

Using the sensor technique for studying photolysis of adsorbed layers of cetene on metal oxides we observed tlie decay of adsorption layers under the influence of ultraviolet light. The reaction yields methylene radicals in the surface layer... 

In Chapter 5.4, optical ultraviolet radiation sensors are described, including UV-enhanced silicon-based pn diodes, detectors made from other wide band gap materials in crystalline or polycrystalline form, the latter being a new, less costly alternative. Other domestic applications are personal UV exposure dosimetry, surveillance of sun beds, flame scanning in gas and oil burners, fire alarm monitors and water sterilization equipment surveillance. 

Figure 4.1 shows atypical absorption spectrum ([Ru(bpy)3]2+, bpy = 2,2 -bipyridine), which is the prototype inorganic photosensitizer and sensor. Note in particular the intense blue-ultraviolet (UV) absorptions and the wavelength independence of the luminescence efficiency. In the blue region, a 10 M solution would absorb over 90% of the light in a 1-cm path length. 

For our purpose, it is convenient to classify the measurements according to the format of the data produced. Sensors provide scalar valued quantities of the bulk fluid i. e. density p(t), refractive index n(t), viscosity dielectric constant e(t) and speed of sound Vj(t). Spectrometers provide vector valued quantities of the bulk fluid. Good examples include absorption spectra A t) associated with (1) far-, mid- and near-infrared FIR, MIR, NIR, (2) ultraviolet and visible UV-VIS, (3) nuclear magnetic resonance NMR, (4) electron paramagnetic resonance EPR, (5) vibrational circular dichroism VCD and (6) electronic circular dichroism ECD. Vector valued quantities are also obtained from fluorescence I t) and the Raman effect /(t). Some spectrometers produce matrix valued quantities M(t) of the bulk fluid. Here 2D-NMR spectra, 2D-EPR and 2D-flourescence spectra are noteworthy. A schematic representation of a very general experimental configuration is shown in Figure 4.1 where r is the recycle time for the system. 

Irradiation Measurements. An Epply photometer with sensors for total global irradiance, photosynthetic active radiation (PAR), and ultraviolet (UV) radiation (295-385 nm) was used to measure irradiance continuously and averaged a measurement every 0.5 h. 

In addition, LNG storage and dispensing systems shall be protected by methane detectors that will sound an alarm and shut down the dispenser. A fire suppression system activated by infrared and ultraviolet flame sensors shall be included to protect the area where the vehicles are refueled. Additional measures such as automatically calling the fire department when the fire suppression system is activated should be considered. 

I. Rohm, M. Genrich, W. Collier and U. Bilitewski, Development of ultraviolet-polymerizable enzyme pastes bioprocess applications of screen-printed L-lactate sensors, Analyst, 121 (1996) 877-881. 

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