Vacuum cleaning

Vacuum cleaning, filtering, d conveying of dry products  [c.936]

Pre-wetting of powders or fibrous solids. This extends to wet sweeping (if vacuum cleaning is impractical).  [c.106]


A major advantage using the multiplier based SMART 160 is that the unit is self contained in its housing so the only cables that are required are the signal cables. This makes it possible to build the X-ray unit into a specially cooled, IP 65 sealed stainless steel housing so that the X-ray unit is protected from the very abrasive cleaning agents used in the food industry. The Tru-Vision unit is built into a similar IP 65 sealed housing opposite the X-Ray unit.  [c.591]

Surface defects (Section VII-4C) are also influenced by the history of the sample. Such imperfections may to some extent be reversibly affected by processes such as adsorption so that it is not safe to regard even a refractory solid as having fixed surface actions. Finally, solid surfaces are very easily contaminated detection of contamination is aided by ultra-high-vacuum techniques and associated cleaning protocols [24].  [c.259]

Thermal insulation. Even slight heat losses considerably disturb the delicate equilibrium of an efficient column, and almost perfect thermal insulation is required for the separation of components with boUing points only a few degrees apart. Theoretically, the greatest efficiency is obtained under adiabatic conditions. If the components boil below 100°, a silvered vacuum jacket is satisfactory the efficiency of such a jacket will depend upon the care with which it is cleaned, silvered and exhausted. In general, the most satisfactory insulation is provided by the application of heat to balance the heat loss. An electrically-heated jacket is fitted round the column the temperature of the jacket, which should be controlled by means of an external resistance or a variable voltage transformer (Variac), should be adjusted within 5° of the temperature of the vapour condensing at the upper end of the column,  [c.95]

Eor food appHcations, improved cleaning of PET produced by secondary recycling is needed. Supercritical fluid extraction using carbon dioxide (20) and solvents such as propylene glycol (26) have been proposed. High temperature and the use of vacuum to remove volatile impurities has also been suggested (27). Stripping of volatile components at temperatures above 160°C for three minutes has been reported (28). AppHcation of multilayer approach, the manufacture of a botde with an inner layer of recycled PET sandwiched between surface layers of virgin PET, is used commercially for soft drink appHcations (29).  [c.230]

In a world increasingly conscious of the dangers of contact with chemicals, a process that is conducted within the walls of a vacuum chamber, such as the VDP process for parylene coatings, offers great advantages. Provided the vacuum pump exhaust is appropriately vented and suitable caution is observed in cleaning out the cold trap (trace products of the pyrolysis, which may possibly be dangerous, would collect here), the VDP parylene process has an inherently low potential for operator contact with hazardous chemicals.  [c.443]

The advantages of packed columns include simple and, as long as the tower diameter is not too large, usually relatively cheaper constmction. These columns are preferred for corrosive gases because packing, but not plates, can be made from ceramic or plastic materials. Packed columns are also used in vacuum appHcations because the pressure drop, especially for regularly stmctured packings, is usually less than through plate columns. Tray absorbers are used in appHcations where tall columns are required, because tall, random-type packed towers are subject to channeling and maldistribution of the Hquid streams. Plate towers can be more easily cleaned. Plates are also preferred in appHcations having large heat effects since cooling coils are more easily installed in plate towers and Hquid can be withdrawn more easily from plates than from packings for external cooling. Bubble trays can also be designed for large Hquid holdup.  [c.19]

Profile dies can be flat plates or the streamline type. Flat plate dies are easy to build and iaexpensive but can have dead spots that cause hang-up, polymer degradation, and shutdowns for cleaning. Streamlined, chrome-plated dies are more expensive and compHcated to build but provide for higher rates and long mns. The land length choice represents a tradeoff long lands give better quaHty profile and shape retention but have high pressure drops that affect throughput. Land length to wall thickness ratios are typically 10 1. Drawdown can be used to compensate for die sweU but should not exceed 25% to minimize orientation. Sizing jigs vary ia complexity depending oa profile desiga water mist, fog, or air cooling can be used. The latter gives more precise sizing. Also, water immersion vacuum sizing can be used. Accurate, infinitely adjustable speed control is important to the takeoff end equipment to guarantee dimensional control of the profile.  [c.206]

Waste Handling. Housekeeping procedures in general can have a significant impact on employee exposure, and certain waste handling procedures can result in very serious exposure if proper precautions are not taken. The best way to keep a plant clean is to not spill in the first place. Management reviews of the origins of spills and accumulated debris not only keep the plant cleaner but prevent loss of valuable material, save cleanup labor, and reduce fire and other safety hazards. Spilled materials in aisles and on walkways can become airborne by redispersion and can be spread onto surfaces and result in skin contact. Dry powders are best cleaned up with either installed or portable industrial vacuum cleaners. Liquid spills can be soaked up using a number of available solvents, and scraped or shoveled into containers. Careful consideration should be given to the methods used to clean floors. Serious worker overexposures have resulted from the use of volatile solvents on large floor areas inside buildings.  [c.106]

Mercury spills should be cleaned up immediately by use of a special vacuum cleaner. The area should then be washed with a dilute calcium sulfide solution. Small quantities of mercury can be picked up by mixing with copper metal granules or powder, or with zinc granules or powder. To avoid or minimize spills, some plants use steel trays as pallets so that a spih, whether of mercury or a mercury compound, is contained on the steel tray.  [c.116]

Vacuum or inert gas operations can produce flammable dusts or powders when opened for cleaning. Most of the hazards are confined to the operator and immediate environs in the operating plant. OSHA is the primary regulator of these hazards in the United States, although many local and state agencies, especially fire departments, also regulate coatings plants. Adequate training, documentation, and protective equipment are the minimum requirements.  [c.138]

The dmm filter consists of a horizontal cylindrical dmm, having from 1 to 5 m diameter, that rotates while partially submerged in an open feed slurry tank. The filter medium is wrapped tightly around the dmm surface. The dmm shell is divided into compartments and drain lines are connected to the central valve system allowing either vacuum or pressure dictated by the cycle. A normal cycle comprises filtration, draining, and discharge by a blast of air or by mechanical means. Cake washing and filter cloth cleaning can also be part of a cycle. Several variations of the standard dmm filters exist, including hyperbaric filters, ie, pressure filtration, up to 600 kPa (87 psi), which are continuous and give high filtration rates and drier cakes (34).  [c.414]

Ion implantation (qv) direcdy inserts nitrogen into metal surfaces. A carefully poHshed and cleaned metal surface at room temperature in a vacuum (-- 0.133 mPa (l-) m Hg)) can be directly implanted with 80-keV nitrogen ions (10) (see Metal surface treatments, case hardening). In an alternative synthesis, argon ions (Ar ) of 8 keV can be used to ionize gas-phase nitrogen to obtain the same results (17).  [c.54]

Commercial oxygen, both gaseous and Hquid, at about 99.5% purity is produced by cryogenic distillation ia air separation plants. In these plants the air is cleaned, dried, compressed, and refrigerated until it partially Hquefies at about 80 K (see Cryogenics). The air is then distilled iato its components (see Table 2). Commercial gaseous oxygen at about 90—93% purity is produced from air by vacuum swiag adsorption (VSA) processes (see Adsorption, gas separation). The VSA method is the fastest growth portion of oxygen production.  [c.477]

Treating a surface with activated gas plasma is a dry process requiring no solvents or rinses of any kind. Using the correct choice of gases and process parameters, plasma cleaning can render a surface atomically clean of organic contaminants and/or activate a surface for enhanced bonding without damage to that surface (121). Figure 7 shows a continuous plasma ftber/wire treatment system that can provide surface treatments in a spool-to-spool or air-to-air mode. The plasma removal of some inorganic contaminants is possible using certain reducing, rather than oxidizing, atmospheres (see Fig. 4a). Plasma surface cleaning is done in a fully contained and controlled vacuum environment. The only effluents are the volatile reaction products of the plasma gas and the surface contaminants (see Fig. 4b). Surface drying by plasma treatment has taken on increased importance in the climate of aqueous-based wet chemical cleaning for environmentally conscious manufacturing.  [c.115]

Oxidative degradation occurs when PTMEG is heated in contact with air (262). Under these conditions, decomposition can start at temperatures as low as 100°C, along with evolution of THE and formation of aldehydes and ketones. Degradation occurs particularly readily when PTMEG is in contact with high surface area materials, eg, pipe insulation. In such cases the heat of oxidative degradation is normally sufficient to sustain the degradation reaction, and spontaneous combustion can occur. Contaminated fibrous insulation should therefore immediately be cooled and discarded. PTMEG is also hygroscopic and should be stored in completely enclosed tanks under a dry nitrogen blanket. Mild steel tanks, tanks lined with phenoHc resin, or stainless steel (type 304) tanks are usually satisfactory. The storage tank must be provided with external or internal heating to maintain a temperature of about 50°C. The storage tanks should be pressure-tested and equipped with a vacuum pressure-reflef conservation vent and an emergency vent. Vents should be heat-traced and insulated to prevent plugging by solidified polymer. New equipment should be cleaned and dried carefully to avoid contamination. If necessary, PTMEG can be dried, eg, by removing water by azeotropic distillation with toluene, by heating (120°C) under reduced pressure (263), or by sparging the hot polyglycol with dry nitrogen.  [c.365]

Thickening and Storage. After screening and cleaning, the pulp has a low consistency, often between 0.5 and 1%. The pulp slurry must be thickened by removing water prior to further processing. Pulp storage is generally termed low or high density. Low density corresponds to a pulp consistency range of 2.5—4 wt %. At these consistencies, the pulp can be pumped by centrifugal pumps and agitated. High density storage corresponds to a consistency of 10—14 wt %. This latter pulp caimot be blended by agitation, but can be pumped by displacement pumps or by special centrifugal pumps termed medium consistency (MC) pumps. From unbleached storage, the pulp is sent to the paper mill for brown grades or to the bleach plant for bleached grades. There is a variety of equipment used for thickening, depending on the level of consistency required. Gravity thickeners usually can achieve discharge consistencies of 4—8% vacuum filters, 12—15% and presses, greater than 20%.  [c.267]

Close-Coupled Single-Stage Hori ntal nd Suction. A closed-coupled pump has an impeller mounted directly on the shaft of the driver, thus eliminating the need for pump-bearing housing. The driver bearings take all pump loads. These pumps are used for relatively light-duty services. They are often appHed for sanitary and corrosive pumping requirements because of a clean-in-place (CIP) capabiUty, ie, the pump can be flushed (cleaned) without much disassembly. This type of pump can handle Hquids and semisoHds having entrained vapors, pump viscous products, and sustain good vacuum characteristics under varying conditions. Designs are simple, and maintenance is easy. These centrifugal pumps use only four basic parts pump hosing or casing, impeller, shaft, and a seal. The shaft, coimected to the power source, eg, a motor, rotates the impeller inside the casing.  [c.291]

Chemically active substances (fluxes) are used to accomplish cleaning and to provide protective shielding when vacuum or protective atmospheres are not available (see Metal surface treatments). However, the use of nonmetallic agents in fluxes is not always desirable owing to the increased propensity for their entrapment and the subsequent formation of voids in the brazed joint. On the other hand, if the brazing environment is not oxidizing, then boron, siUcon, and phosphoms, which are used as inherent constituents of FM alloys, can play the role of a flux, ie, reducing original oxide films and making the FM self-fluxing.  [c.241]

The choice of metals for vacuum walls is largely based on the ease of fabrication of the metal, machining, cleaning (26), welding, etc. Aluminum alloys are the material of choice for out-gassing at room temperature.  [c.376]

D. J. Mattox, Surface Cleaning in Thin-Film Technology, American Vacuum Society, New York, 1975.  [c.379]

Hand and power tool cleaning is used on ships mostly for spot repair of damaged areas. Hand tools include scrapers, wire bmshes, and sanders. Electric and pneumatic power tools, which include grinders and needle guns, clean faster and more thoroughly than hand tools. Most power tools have vacuum lines coimected to collect paint debris.  [c.365]

Deposition. Lens spoilage from tear film deposition is a common reason for lens replacement and mandates the frequent cleaning of nondisposable contact lenses. When deposits become significant, they affect vision, lens properties (45), and ocular health (46). Deposits that form on contact lenses are complex and contain proteins, hpids, and minor components such as calcium (47,48). The mechanism of deposit formation is of research interest and draws on work in the biomedical device field (49,50). Studies have shown that for hydrophilic lenses deposition depends on material polymers containing a charged species show greater deposition than uncharged polymers (51,52). Although no standardized tests exist for the measurement of deposition, each manufacturer has empirical tests to screen materials for protein or hpid deposition potential. These tests are not 100% predictive, because actual lens deposition is a function of lens type, patient tear chemistry, cleaning and disinfection regimen, and environment.  [c.101]

A rotating vacuum dryer is formed by equipping a double-cone mixer with a jacket and an internal vapor exit tube passing through a rotary joint in one tmnnion. Volume capacity is 0.1—30 m. FiEage is 50—70% of total volume. Internal operating pressures are 1—10 kPa (0.15—1.5 psi). In dryers operated at 1.5 kPa, having jackets heated by 200 kPa saturated steam, water evaporation based on total heated surface is 4—5 kg/(h-m ). Rotating vacuum dryers are suitable for materials that do not stick to metal when wet or dry and do not pelletize during drying. Feed conditioning is an option. The ratio of jacket surface to operating volume decreases as dryer size increases, so large dryers often include internal plate or pipe coils to compensate. These internal elements partially destroy a principal attraction of the dryers, however, which is ease of complete emptying and cleaning between batches.  [c.256]

Pan. Indirect type, batch operation Atmospheric or vacuum. Suitable for small batches. Easily cleaned. Solvents can be recovered. Material agitated while dried See comments under Liquids See comments under Liquids See comments under Liquids Suitable for small batches. Easily cleaned. Material is agitated during drying, causing some degradation Not applicable Not appbcable Not appbcable  [c.1187]

In styrene service, vapor may condense in flame arresters, and the liquid formed is low in inhibitor. Liquid may polymerize and plug off the arrester. Possible solutions include cleaning the arrester frequently or using a PVRV (pressure-vacuum relief valve).  [c.2335]

Most fugitive dust is derived from spillage of stone fines and overburden soil from conveyors, bucket elevators, loading spouts, tmcks, etc from stockpiled-processed stone and spall piles that become air-dried and then wind-blown and from tmck traffic and wind on plant roads. Spillage can be minimized by a variety of practices including not overloading conveyor belts, elevators, and tmcks better coordination of the stone-feed flow reducing conveyor gravity drops use of enclosures at vulnerable transfer points use of retractable loading spouts that fit tightly in circular ports of tank tmcks hberal appHcation of rainbird-type jet-spray systems on stockpiles watering unpaved areas removing dust from paved surfaces with vacuum-cleaning equipment reducing tmck speed or using pneumatic pumplines in place of tmcks. Successful dust abatement requires a weU-supervised, unremitting campaign, supported by all levels of management.  [c.170]

This discussion will address needs, applications, performance characteristics, and design considerations for LVHV exhaust ventilation. The applications are primarily for dust control. LVHV systems can be effective for protecting workers from dust exposures and for recovering valuable process materials. The equipment, excepting the nozzles, involves technology that is the same as for large central vacuum cleaning systems.  [c.852]

Fixed Duct/Tubing The ducts for LVHV systems ordinarily consist of steel tubing designed to minimize turbulent pressure losses and convey airborne dust to an air cleaner. The type of steel-tubing duct that is used in cen tral vacuum cleaning systems is good for LVHV applications. It is designed with long-radius turns and smooth inside joints between the fittings and straight duct sections. The duct fittings have expanded ends to allow a slip-fit with the straight duct and a smooth joint on the inside surface of the duct. The slip-fit components are positioned and welded to create a strong and smooth airflow system.  [c.864]

Air Cleaner/Dust Collector There are a wide variety of possible types of air-cleaning equipment for LVHV systems. The most common is a fabric dust collectot, having a vertical cylindtical baghouse design. This type is common in large central vacuum cleaning systems. Other types of fabric collectors can also be used. For applications involving substantial amounts of large dust particles, it is usually a good idea to have a cyclone-type primary separator upstream of a fabric collector.  [c.865]

Figure 10.30 illustrates a multiple-stage exhauster and smooth-flow duct (pneumatic tubing) components. It also includes pictures of air cleaner-exha uster-motor installations located outside of buildings and connected to LVHV (or central vacuum cleaning) systems inside the buildings.  [c.865]

Hoffman Air Systems. High Velocity Dust Control and Central Vacuum Cleaning Systems. Bulletin A.SV-623A. New York Hoffman Air Systems, 1973.  [c.914]

Experiments were carried out with a Pt(l 11) single-crystal surface cleaned in an ultrahigh-vacuum system. To monitor the progress of the reaction as a function of time, the researchers brought O, into contact with the Pt to give a surface partially covered with O atoms, which aggregate into islands with a distinct periodic stmcture the O atoms show up as dark dots in islands in the image of figure C2.7.9 at time 0. At time 0, CO was introduced into the reactor and bonded with the surface, thereupon reacting with the chemisorbed O and reducing the sizes of the islands, as shown by the STM images at increasing times after the introduction of CO (figure C2.7.9). The CO molecules that must have been present on the surface at short times were not visible because of their high mobilities. But after 290 s, and more clearly after 600 s, the O islands had markedly slirunk because of reaction, and the CO had become evident as an additional ordered, streaky stmcture (figure C2.7.9) at these times the CO had fonned into closely packed immobilized stmctures. After longer times, the O islands became smaller, indicating the progress of the catalytic reaction by 2020 s, the O had been completely converted (figure C2.7.9). Note the contrast with the NO decomposition reaction the CO oxidation takes place on the flat metal surface, not just on minority sites such as steps.  [c.2709]

These p-nitropropene crystals the chemist now has can be air-dried and used as is, but that is not advisable. What they need is a little more cleaning up, and one does this by performing recrystallization. To do this the chemist is going to use a solvent that everything in the reaction that the crystals came from is soluble in but that the crystals are not. Get it No Well, to demonstrate, the chemist will boil 200mL of methanol in a beaker and start knocking chunks of the impure p-nitropropene filter cake into the hot solvent. If all of the crystals will not dissolve in the 200mL of methanol then more is added and heated to accommodate. As soon as all the crystals are added and have dissolved, then the chemist turns off the heat and chills the mixture to 0-5°C. What is going to happen is that everything the chemist doesn t want will remain dissolved in the now cold methanol, but all of the p-nitropropene crystals will recrystallize when cold. This solution is now vacuum filtered and the now clean crystal filter cake is washed with a little bit of extra, cold methanol just to make sure. That extra methanol washing and the filtrate can be reduced in volume by distillation and chilled to retrieve a second crop of p-nitropropene crystals (total conversion is around 70%). The final thing to add is that the chemist has a choice of recrystallization solvents other than methanol. These include hexane, isopropyl alcohol and ethanol.  [c.129]

Using a standard vacuum distillation the solvent is distilled off. This shouldn t take too long. The first thing to come over after the solvent was the safrole, which with my vacuum (2mm) started at around 9CfC. The safrole will be a clear liquid, slightly viscous and will smell of liquorice. With the above measurements one can expect a yield of around 85g. No further cleaning up is necessary, and the safrole can be used as is for any further reactions.  [c.237]

It has been suggested that gold does not have a stable surface oxide (227), and therefore, its surface can be cleaned simply by removing the physically and chemically adsorbed contaminants. However, more recently it has been shown that oxidation of gold by uv and ozone at 25°C gives a 1.7 0.4 — nm thick AU2O2 layer (228), stable to extended exposure to ultra high vacuum (UHV) and water and ethanol rinses.  [c.540]

Filtration. Efficient filtration for removal of suspended particles is essential for sparkling pool water. Edters may be of the fixed-bed, precoat, or cartridge type and operate under vacuum or pressure. The most common filter media are sand, anthracite, diatomaceous earth (DE), and paper or cloth cartridges. The cartridges remove particles as small as 15 )J.m, sand to 25 )J.m, and DE to 3 ]lni (61). Since the visual limit is 30—35 )J.m, most properly operating filters do a satisfactory job. Sand and DE filters are backwashed, whereas cartridge filters are cleaned manually by rinsing in water. Backwashing removes accumulated insoluble matter which would eventually increase resistance to fiow (head) and reduce filtration rates. Elocculents for retention of surface dirt on sand filters are not recommended (2). Diatomaceous earth filters requite a precoat of DE after each filter cycle (see Diatomite). Use of compressed air (bumping) to dislodge the DE followed by recoating the filter with the dislodged DE reduces water usage and allows longer filter cycles. The DE is sometimes mixed continuously with unfiltered water before entering the filter. The pump serves not only to cinculate pool water through the filter and chlorinator but also to mix the pool water, thereby diluting and dispersing sanitizers and other additives whether added manually or through feeders. Typically, pumps are sized to achieve one pool water turnover in about 6 h. Vacuum cleaners, which derive thek suction from the filter pump, are used to remove sofids from the walls and bottom of the pool. Some automatic pool cleaners moving around the bottom of the pool are efficient enough to eliminate the need for hand vacuuming.  [c.302]

Moisture is removed from flised sUica by heating, preferably in vacuum. Prior to this, sUica ampuls are sometimes rinsed with a detergent solution, hydrofluoric acid, nitric acid, or methanol. After cleaning, drying, and loading, the ampul may be alternately evacuated and back-fUled with inert gas. Sealing is easier if the inert-gas pressure is only slightly below atmospheric.  [c.451]

Recycling of cemented carbide scrap is of growing importance. In one method, the scrap is heated to 1700—1800°C in a vacuum furnace to vaporize some of the cobalt and embrittle the material. After removal from the furnace the material is cmshed and screened. In chemical recycling the cobalt is removed by leaching, leaving carbide particles intact. In the zinc red aim process, commercialized in the late 1970s, the cleaned scrap is heated with molten zinc in an electric furnace under inert gas at - 800° C. The zinc reacts with the cobalt binder and the carbide pieces swell to more than twice their original volume. The zinc is distilled off in vacuum and reclaimed. The treated carbide pieces are pulverized and screened to produce a fine powder. The cobalt is stiU present in the particles and there is no change in grain size from the original sintered scrap. The Coldstream reclaim method employs a high velocity airstream to accelerate cemented carbide particles against a target surface having sufficient energy to cause the particles to fracture. The Coldstream process, so called because the air cools as it expands from the nozzles, is employed in combination with the zinc reclaim process.  [c.443]

Abrasive Blasting. Blast cleaning using mineral abrasives (qv) is the preferred method for cleaning steel prior to applying marine coatings. Blasting not only provides the highest level of cleanliness but also roughens the surface to provide for good adhesion of the primer. As much blasting as possible is done in purpose-built enclosures to minimi2e the amount of particulates produced and to provide better and less cosdy cleaning. Shop blasting is accomphshed by equipment having high speed rotating wheels that propel shot or grit abrasive onto steel. Portable closed-cycle vacuum blasting equipment is available for field use. Special machines have been made for steel decks and hulls which recycle the abrasive several times, saving cosdy abrasive and reducing the amount of blasting waste.  [c.364]

All contact lenses tend to accumulate debris, deposits, and discolorations on and sometimes below the surfaces (7). The deposits are usually proteinaceous or Hpid but may also be inorganic compounds and microorganisms, eg, fungi and bacteria. The source of these deposits is usually the eye itself, the tear film that bathes the surface tissues, the eyefld glands, the mucoid substance secreted by certain conjunctival cells, or the immunoglobulins secreted through the vascular system. Although regular cleaning and disinfection can control these accumulations and reduce the likelihood of clinical problems such as reduced vision, inflammation or red eye, abrasion, and infection, the deposits are considered undesirable (8,9).  [c.100]

Horizontal-Table Scroll-Uischarge and Pan Filters These are all basically revolving aumJar tables with the top surface a filter medium (Fig. 18-128). The table is divided into sectors, each of which is a separate compartment. Vacuum is apphed through a drainage chamber beneath the table that leads to a large rotary valve. Shiny is fed at one point, and cake is removed after completing more than three-fourths of the circle, by a horizontal scroll conveyor which elevates the cake over the rim of the filter. A clearance of about 10 mm (0.4 in) is maintained between the scroll and the filter medium to prevent damage to the medium. Residual cake on the medium may be loosened by an air blow from below or with high-velocity hquid sprays from above. This residual cake is a disadvantage peculiar to this type of filter. With material that can cause blinding, frequent shutdowns for thorough cleaning may be needed. Unit sizes range from about 0.9 to 7 m (3 to 24 ft) in diameter, with about 80 percent of the surface available for filtration.  [c.1717]

See pages that mention the term Vacuum cleaning : [c.864]    [c.112]    [c.134]    [c.14]    [c.11]    [c.1715]   
Industrial ventilation design guidebook (2001) -- [ c.1446 ]