Secondary filter

Secondary filter A filter to provide final cleaning of the air after the main filter in a system. 

Fig. 29 Fluorescence scans of polycyclic aromatic hydrocarbons at various excitation wavelengths in combination with various secondary filters.

Instruments for the measurement of fluorescence are known as fluorimeters or spectrofluorimeters. The essential parts of a simple fluorimeter are shown in Fig. 18.1. The light from a mercury-vapour lamp (or other source of ultraviolet light) is passed through a condensing lens, a primary filter (to permit the light band required for excitation to pass), a sample container, a secondary filter (selected to absorb the primary radiant energy but transmit the fluorescent... 

Procedure. Measure the fluorescence of each of the above solutions at 445 nm, using that containing 62.0 mL of the dilute quinine solution as standard for the fluorimeter. Use LF2 or an equivalent primary filter (/cx = 350 nm) and gelatin as the secondary filter if using a simple fluorimeter. 

Secondary filter hose, process filters, PPE, experience) Worn scabbling bits, swipes. 

Fig. 2.46. Basic principle of a venting filter for in situ integrity tests. Arrangement of the sterile venting filters for in-line sterilization and integrity tests (I tests). The integrity tests are carried out following the water intrusion method (WIT). In this figure, WIT is carried out only at the primary filter. The secondary filter is installed as a back-up filter (police filter). 1, Primary filter with a 0.22 pm cartridge 2, secondary filter with a 0.22 pm cartridge the secondary filter can be sterilized independent-...

Fig. 55. Schematic representation of a fluorimeter 1 mercury discharge lamp, 2 diaphragm, 3 lens. 4 heat filter, 5 primaiy filter, 6 cuvette, 7 secondary filter, 8 photodetector, 9 measurement at an angle of 90° to the incident light.

Level 2 and 3 Production facility operating on 100% outside air primary plus secondary filters (e.g, EN779 G4 plus F8 filters)... 

A room cleanliness classification is a critical parameter and, therefore, the room air-change rates and high-efficiency particulate air (HEPA) filters should be critical parameters and require qualification. Items such as the fan generating the airflow and the primary and secondary filters are non-critical parameters, and may not require operational qualification. 

Fig. 1. Cobalt content in secondary filtered wax during pilot plant scale Fischer-Tropsch synthesis runs, using catalyst A 30gCo/0.075gPt/100gAl203 (run F102).

The dissolution behaviour of the alumina support during the slurry phase impregnation steps of the catalyst preparation procedure was considered to be the cause of the high levels of cobalt-rich ultra fine particulates in secondary filtered wax. To prevent dissolution of the alumina support during the slurry phase impregnation step of the catalyst preparation procedure, a support modification procedure was developed to prevent acidic attack of the hydroxyl groups on the surface of the support. A modifier was chosen which had to conform to the following requirements ... 

Describe the instrumentation required for fluorescence analysis. What is a primary filter A secondary filter ... 

Filters may be divided into two basic types, depending on the method of the filtration material recovery — primary and secondary. Primary filters work under conditions of a continuous regeneration of the filtration material (input dust concentrations in g m ), and secondary filters operate with periodic exchanges of the filtration material after clogging (input concentrations in mg m ). 

Figure 9.3. Schematic diagram (top view) of the components of a fluorometer (filter fluorometer or spectrofluorometer). The source is a mercury-arc or xenon-arc lamp. The excitation grating or primary filter transmits only a portion of the radiation emitted by the source. Most of the exciting radiation passes through the sample cell without being absorbed. The radiation absorbed causes the sample to fluoresce in all directions, but only the emission that passes through the aperture or slit and through the secondary filter or fluorescence grating is measured by the phototube, or photomultiplier. The output of the detector is either measured on a meter or plotted on a recorder. From G. H. Schenk, Absorption of Light and Ultraviolet Radiation, Boston Allyn and Bacon, 1973, p 260, by permission of the publisher.

Selecting a Secondary Filter and Measuring Emission. After penetrating the aperture, the emitted luminescence passes through a secondary filter or fluorescence grating that eliminates any scattered radiation. The bandwidths of the primary and secondary fitters should not overlap. For example, if a 7-60 primary filter were used, then the secondary filter chosen should not transmit below about 400 nm a good choice would be the so-called 2A secondary filter shown in Figure 9.5B. 

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