Mercury medium-pressure unit

Surface water photolysis t,/2 = 0.78 h (reported in units of minutes) in aqueous solution when irradiated with a 500 W medium pressure mercury lamp (Chen et al. 1996). 

Table 1 contains 1995 estimated materials costs for a single photo-thermal detoxification unit chamber fitted with six 15-kW medium-pressure mercury lamps. Labor and licensing costs were not included (D117317, p. 9). 

Many technical applications require high radiant power, which cannot be furnished by an operationally reasonable number of lamps having otherwise optimal emission characteristics. Examples of this situation are mostly found in applications oTthe 254-nm fine, where a number of low-pressure mercury lamps may be replaced by one medium-pressure mercury arc. This substitution represents a compromise where spectral selectivity and energy wasting (VIS and IR radiation) is traded against a compact production unit which is less expensive (number of reactors, quartz, safety requirements) and easier to operate (number of reactors, space, and overview). 

Two mercury arc lamps with associated power units are available (a) a 2 watt low-pressure U-shaped lamp which emits mainly at 186 nm and 254 nm, and (b) a 100 watt medium-pressure straight-tube lamp emitting predominantly at 254 nm, 265 nm, 297 nm, 313 nm and 366 nm with intense emission also in the visible region both lamps have synthetic quartz envelopes. 

These specific calculations yield the amount of 253.7 nm photons (mol photons) that are produced (under optimal conditions) during 1 h of irradiation with common industrial low-pressure or medium-pressure mercury lamps, respectively. Also, (Dp may be expressed in mol photons per second which is equivalent to the older unit einstein s-, or the number of photons per second emitted by the lamp can be calculated (Tab. 3-4). 

An RFC model QC-1202 processor was used for UV curing. The unit was equipped with two 12 Inch medium pressure mercury arc lamps and a variable speed conveyor (50 to 500 ft/min). Only one lamp was used at a time In the testing (operated at 200 watts/ln). The DV energy dosage was measured by passing a UV Process Supply Compact Radiometer under the lamp on the conveyor belt. 

Most compositions were cured in air with a Linde MPHg unit employing three 2.2 KWr medium pressure mercury arc lampsr each 24 inches in length positioned parallel to the travel of the moving belt. The total delivered flux was estimated at 500 Watts/sq.ft. 

To understand the primary photochemistry of 6F-PIs in air, Hoyle et al. [I72-I74] used V-phenylphthalimide as a model compound, since this model probably reflects the structural units in 6F-PIs where conjugation between the diimide groups is prevented by the C(CF3)3 bridge. Upon irradiation with a Pyrex filtered medium pressure mercury lamp, this model in an air-saturated acetonitrile solution rapidly decomposes to form phthalic anhydride (quantum yield major product, phthalimide (0 = 2X and a trace amount of nitrobenzene (this originates probably from... 

The porosity of a catalyst or support can be determined simply by measuring the particle density and solid (skeletal) density or the particle and pore volumes. Particle density pp is defined as the mass of catalyst per unit volume of particle, whereas the solid density p, as the mass per unit volume of solid catalyst. The particle volume Vp is determined by the use of a liquid that does not penetrate in the interior pores of the particle. The measurement involves the determination by picnometry of the volume of liquid displaced by the porous sample. Mercury is usually used as the liquid it does not penetrate in pores smaller than 1.2/m at atmospheric pressure. The particle weight and volume give its density pp. The solid density can usually be found from tables in handbooks only in rare cases is an experimental determination required. The same devices as for the determination of the particle density can be used to measure the pore volume V, but instead of mercury a different liquid that more readily penetrates the pores is used, such as benzene. More accurate results are obtained if helium is used as a filling medium [10]. The porosity of the particle can be calculated as ... 

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