Lamps germicidal

The electrical uses of mercury include its application as a seal to exclude air when tungsten light bulb filaments are manufactured. Fluorescent light tubes and mercury arc lamps that are used for street lighting and as germicidal lamps also contain mercury. 

General Electric 4 watt germicidal lamp and a Corion Corporation 2537 interference filter (15% transmission at 2537). The Fluoromonitor s emission detection unit consisted of a RCA 931B (S-4 spectral response) photomultiplier tube and a Corning 7-51 glass filter that transmits light of wavelengths between 310 and 410 nm. 

When an aseptic room is not in use the air may be sterilised by use of UV germicidal lamps. These should be installed in a position such that the whole room is illuminated and should be sufficiently powerful to be effective at the extreme comers of the room. 

H2O2 photolysis is usually performed with low- or medium-pressure mercury vapor lamps. Almost 50% of the energetic consumption is lost in the form of heat or emissions less than 185 nm, which are absorbed by the quartz jacket. Generally, cheap germicidal lamps are used however, as H2O2 absorption is maximal at 220 nm, it is more convenient to use Xe/Hg lamps that—although more expensive—emit in the 210-240 nm range. 

The larger reactor operates under a steady state, continuous flow conditions and was made of two 1 m cylindrical reactors of annular shape in order to use conventional Germicidal lamps (Figure 14). The system of tanks shown in the flow sheet was used to (i) feed the reactor with a constant flow rate and (ii) wash the system after each experimental run. The actual operating length (Zi) of each lamp (1.2 m long) was Im. Operation could be made with just one reactor or the two in series. 

UV radiation from the Sun is a ubiquitous and important source of DNA damage that contributes to the high incidence of skin cancer in exposed individuals. The UV radiation spectrum has been arbitrarily divided into the UV-A component (wavelengths 320 00 nm), the UV-B component (wavelengths 295-320 nm), and the UV-C component (wavelengths 100-295 nm). Penetration of the atmospheric ozone layer is weak for wavelengths below 300 nm. Thus, solar UV radiation primarily comprises the UV-A and UV-B components. However, experimental studies typically involve the use of UV-C radiation from germicidal lamps with a sharp emission maximum at 254 nm. Since... 

Fig. 1. UV spectram showing germicidal lamp output versus the effectiveness of germicidal destruction at that wavelength. ...

SET launches UVLED germicidal lamp, Compoimdsemiconductor.net, February 21, 2006. 

Differences in catalytic activity of the three photoinitiators are most obvious when the coatings are exposed to a source of predominantly visible light, such as sunlight, or to a source of shortwave radiation, such as a germicidal lamp. Table VI shows the time required for 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexane carboxylate (ECC) photosensitized with the three photoinitiators to become tack-free when exposed to various sources of light. 

It can be seen that under the influence of sunlight, PM will initiate polymerization readily, while neither DPI nor TPS produces a cure. Under the germicidal lamp, which emits 254 nm radiation almost exclusively, the situation is reversed, with DPI and TPS which are strong absorbers of the shorter wavelength radiation, being somewhat more effective than PM. 

Finally, another potential interplay between UVR and viruses occurs when they coexist with their host in a type of mutualistic relationship, where the nucleic acid of the virus is integrated in the genome of the host and is replicated with it (lysogenic state). Ultraviolet C radiation produced by germicidal lamps (max. at 254 nm) has normally been used, among other stressors, to induce the shift from lysogenic to lytic state in a complex mechanism involving the DNA repair SOS system of the host [93]. However, natural or simulated solar UVR seems not to be very efficient in this process [94,95]. 

A pilot plant scale, tubular (annular configuration) photoreactor for the direct photolysis of 2,4-D was modeled (Martin etal, 1997). A tubular germicidal lamp was placed at the reactor centerline. This reactor can be used to test, with a very different reactor geometry, the kinetic expression previously developed in the cylindrical, batch laboratory reactor irradiated from its bottom and to validate the annular reactor modeling for the 2,4-D photolysis. Note that the radiation distribution and consequently the field of reaction rates in one and the other system are very different. 

---