Filters fiberglass

Figure 37-6. A depth filter, fiberglass bonded with an acrylic (2,600x)...

Fiberglass manufacturing scrubber sludge Secondary and synthetic fiber Chemicals Variable-volume filter press 3 37... 

HEPA filters consist of a filter pack sealed into a case. The filter pack or core is made by pleating a continuous web of fiberglass paper back and forth over corrugated separators. The filter pack is sealed into a full-depth wood or steel casing using a elastomeric sealant. Gasketing is a critical item to ensure that the filter passes the air leakage tests. 

Reverse-flow-cleaned filters are similar to the shaker-cleaned design, except the shaker mechanism is eliminated. As with shaker-cleaned filters, compartments are taken off-line sequentially for cleaning. The primary use of reverse-flow cleaning is in units using fiberglass-fabric bags at temperatures above 150°C (300°F). 

The instances cited were examples of the use of DEP to filter liquids. We now turn to the use of DEP to aid in dielectrofiltration of gases. Fielding et al. observe that the effectiveness of high-quality fiberglass air filters is dramatically improved by a factor of 10 or more by incorporating DEP in the operation. Extremely little current or power is required, and no detectable amounts of ozone or corona need result. The DEP force, once it has gathered the particles, continues to... 

The cleaning action of a fabric filter is based on the assumption that the air will pass through the fabric while the particles are retained (Fig. 16-2). The gases must be cooled to 180°F (82°C) if cotton bags are used and 550°F (288°C) if fiberglass is... 

Fibrous bed coalescers generally have a fixed filter element constructed of fiberglass or other material that acts to coalesce (bring together) the oil droplets and to break emulsions. The coalesced oil droplets released from the filter are readily separated downstream by gravity. Coalescence in a fibrous bed coalescer involves three steps ... 

Toxi-ChromoPad (EBPI, Ontario, Canada) is a simple method for evaluation of the toxicity of solid particles [25,26,32,39]. The test is based on the inhibition of the synthesis of (3-galactosidase in E. coli after exposure to pollutants. The method has been used to measure acute toxicity of sediment and soil and other solid samples. The test bacterial suspension is mixed with homogenized samples and incubated for 2 hours. A drop of the test solution is pipetted onto a fiberglass filter containing an adsorbed substrate. A color reaction indicates the synthesis of enzyme, while a colorless reaction indicates toxicity. It has previously been shown... 

Electrostatic precipitators and baghouses are used to catch dust particles containing metals. Electrostatic precipitators use an electrical field to remove the particles. Baghouses use fiberglass filters, similar to vacuum cleaner bags, to catch them. The majority of theses particles, called cement kiln dust (CKD), are trapped by this equipment and returned to the kiln for incorporation into the cement clinker. Under USEPA s BIF rule. Southdown tests its cement kiln dust to judge whether it is hazardous. If the CKD does not meet the standards set under the BIF rule, it must be disposed of in accordance with USEPA s strict hazardous waste regulations. For that reason. Southdown does not accept fuels that would cause the waste CKD to fail this test. 

Preparation of N0X samplers involves the insertion of a chromic acid disc behind the TEA-treated screens held in the sampler. The disc, made by soaking fiberglass filters in an aqueous solution of Na2Cr207 and H2SO4, oxidizes NO to NO2. 

The principles behind ultrafiltration are sometimes misunderstood. The nomenclature implies that separations are the result of physical trapping of the particles and molecules by the filter. With polycarbonate and fiberglass filters, separations are made primarily on the basis of physical size. Other filters (cellulose nitrate, polyvinylidene fluoride, and to a lesser extent cellulose acetate) trap particles that cannot pass through the pores, but also retain macromolecules by adsorption. In particular, these materials have protein and nucleic acid binding properties. Each type of membrane displays a different affinity for various molecules. For protein, the relative binding affinity is polyvinylidene fluoride > cellulose nitrate > cellulose acetate. We can expect to see many applications of the affinity membranes in the future as the various membrane surface chemistries are altered and made more specific. Some applications are described in the following pages. 

Fig. 4 Superfusion neurotransmitter release assay in synaptosomes. (a) Schematic drawing of a superfusion setup. Synaptosomes are preloaded with radioactive neurotransmitter and captured on fiberglass filters in superfusion chambers under continuous superfusion with gassed physiological salt solution (e.g., Krebs bicarbonate buffer) using a peristaltic pump. After a 10- to 15-minute wash, neurotransmitter release is triggered by rapid switching of superfusion lines to a stimulating buffer (e.g., high-potassium solution). Superfusate is collected on a fraction collector, and radioactivity is measured by liquid scintillation, (b) Typical trace recording of tritium-labeled norepinephrine fractional release in rat cortical synaptosomes stimulated by high potassium and a-latrotoxin in the presence or absence of external calcium.

The storage and transfer of raw chemicals requires special considerations relative to the equipment that come into contact with epoxy resins. Carbon steel is generally satisfactory for pipe and tank construction and will not rust beneath the epoxy resin. Rust occuring above the level of the epoxy and accidentally introduced into the resin may be removed by filters. Epoxy coated steel pipe, aluminum or stainless steel pipe, or epoxy fiberglass composite tubing is used to prevent rusting downstream of the filter. 

The emission measurements during this testing included N0X, smoke, particulate and PNA. N0X was determined by a non-disper-sive infrared analyzer, and smoke by the Bacharach test. Both the particulates and PNA were sampled by a source assessment sampling system (SASS). The SASS system isokinetically samples a fraction of the stack gas and traps particulates in a series of cyclones, which classify the particulate by size. Final filtration is through a fiberglass filter mounted in an oven heated to 200°C to prevent condensation of acids. In this program, the cyclones were not used, since previous work (3) had shown the particulate from coal-derived fuel oils to be small, with an average diameter on the order of 0.4 /um. The PNA which is not deposited on the particulate is collected on XAD-2 resin after the gas has been cooled to 15-20°C. PNA analyses were carried out on a combined extract from the particulate, XAD-2 resin, other condensates in the system, and the solvent rinses used to clean the SASS system. 

For the preparation of the peanut skin tannin, the red skins were separated from residual nut and hull material by hand sorting, and then about 30 lb of skins were extracted with acetone-water (60 40 v/v) at a liquor-to-skins ratio of 5 to 1 at 50 °C for 4 hr in a stainless steel tank. The extract was filtered through a fiberglass mat, the acetone was removed under vacuum on a rotary evaporator, and the aqueous solution was freeze-dried. 

---