Steam Cleaning Research Articles

A topographical assessment and comparison of conservation cleaning treatments

The development of laser cleaning as a conservation treatment has imposed a need for the evaluation and assessment of other cleaning techniques. The use of more traditional methods like abrasive cleaning, steam cleaning and chemical cleaning has relied so far on visual assessment, unlike much of the research applied to laser cleaning. A conscientious use of these cleaning methods requires their assessment as well as the need for a comparison based on a common methodology. A topographical assessment of laser cleaning, abrasive cleaning, steam cleaning and chemical cleaning (using hydrofluoric acid, ammonium carbonate and EDTA) is presented. Topographical variations induced on marble, oolitic limestone and architectural terracotta surfaces are assessed by means of light interferometry, showing the potential of this non-contact and non-destructive technique for surface studies in conservation. The comparison between cleaning treatments is based upon key parameters associated with cleaning surfaces. The aesthetic impact of these treatments is verified by means of optical microscopy and quantified by colour measurement. Chemical analysis of the cleaned surface (EDS) is performed to investigate the removal of surface pollutants and the presence of residues. Finally, petrographical analysis was used to investigate the removal of pollutant layers and its effect on surface texture.

KrF excimer laser dry and steam cleaning of silicon surfaces with metallic particulate contaminants

KrF excimer laser-assisted dry and steam cleaning of single-crystal silicon wafers contaminated with three different types of metallic particles was studied. The laser fluence used was 0.3 J/cm2. In the dry process, for samples cleaned with 100 laser pulses the cleaning efficiency was 91, 71 and 59% for Au, Cu and W particles, respectively, whilst in steam cleaning the efficiency is about 100% after 5 laser pulses, independently of the type of contaminant. The effects of laser irradiation on the Si surface are investigated by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). Laser processing at 0.3 J/cm2 does not deteriorate the Si-wafer surface, either in dry or steam cleaning. However, the measured XPS intensity coming from the metallic component is greater on the cleaned surfaces than in the initial condition. Quantification of the XPS results, assuming a stratified overlayer model for the detected species and accounting for the presence of the metallic particles on the surface, showed that the obtained results can be explained by the formation of a fractional metallic monolayer on the cleaned surfaces, due to partial vaporisation of small particles initially present on the sample surface. This contamination of the substrate could be considered excessive for some applications and it shows that the process requires careful optimisation for the required efficiency to be achieved without degradation of the substrate.

Explosive Boiling of Water Films Adjacent to Heated Surfaces: A Microscopic Description

Molecular dynamics simulations are used to investigate the separation of water films adjacent to a hot metal surface. The simulations clearly show that the water layers nearest the surface overheat and undergo explosive boiling. For thick films, the expansion of the vaporized molecules near the surface forces the outer water layers to move away from the surface. These results are of interest for mass spectrometry of biological molecules, steam cleaning of surfaces, and medical procedures.

The modeling of excimer laser particle removal from hydrophilic silicon surfaces

We summarize experimental results on the successful removal of submicron-sized polystyrene latex, carboxylate-modified latex, SiO2, and Al2O3 particles from hydrophilic silicon surfaces by excimer laser, using both dry and steam cleaning; the cleaning and damage thresholds have also been determined for these particles. Adhesion and removal models for an ideal sphere particle, that include van der Waals forces, hydrogen bonding, and thermoelastic effects, theoretically explain the laser cleaning results. Two models of the removal force due to the explosive evaporation of liquid film have been calculated and compared. The effects of both asperities on the particle surface and particle aggregation have also been considered. The results of the calculations show that even those surface asperities which are small compared with the particle dimension can cause a large reduction in both adhesion and thermoelastic removal forces. The theoretical predictions are consistent with the experimental observations.

Developments in the application of laser technology for conservation

Although laser cleaning of artworks was first demonstrated over 30 years ago. it is still considered by many as a ‘new’ technique and it is only relatively recently that it has been accepted alongside more traditional methods. such as steam cleaning and solvent cleaning. The laser is complementary to these techniques and its introduction has been seen by many as a significant refinement of conservation techniques. The intense, pure form of light emitted by a laser allows the conservator, in many but not all cases, to remove unwanted soiling from a fragile surface in an extremely precise and controlled manner. This paper aims to give the reader a realistic understanding of what can be achieved using a laser.

The use ofdomestic steam cleaning for the control of house dust mites

Control of dust mites using extremes of temperature is an alternative to the use of acaricides. In the past we have attempted control by freezing with liquid nitrogen. The present paper deals with the opposite extreme, the use of steam. To assess the feasibility and effectiveness of a domestic steam cleaner for the control of dust mites, its effect on mite populations and concentrations of the allergen Der p 1. A domestic steam cleaner was used to treat carpet squares that had been seeded in the laboratory with known numbers of dust mites (Dermatophagoides pteronyssinus). The number of live mites was monitored for a period of 4 months in eight treated carpet squares and eight controls. Dust samples were taken from 12 standardized areas of carpet in a tenement flat in Glasgow, UK, before and after steam cleaning treatment, and the concentration of allergen Der p 1 was compared with 12 adjacent, control areas. No live mites were found at any time in the treated carpet squares, whereas in the control squares geometric mean mite population density rose from 11 after 3 days to 39 after 1 month, 66 after 2, 122 after 3 and 185 after 4 months. There was a mean reduction of 86.7% in Der p 1 concentration (3.3-0.44 microgram/g) compared with a reduction of 4.7% (2.22-2.116 micrograms/g) in control areas, a difference that was statistically significant at the 5% level. These data indicate that steam cleaning has considerable potential as an highly effective and efficient method of killing dust mites and reducing concentrations of Der p 1 in domestic premises.

Numerical analysis of electric field in a closed space injected with charged fluid

The electric field in a closed space, where existing fluid is replaced by inflow of charged fluid, is sometimes of great importance in safety. The past method of calculation might bring a large error in the safety evaluation, since the method assumes the homogeneous distribution of electric charge and does not take into consideration its heterogeneity due to the charge transport by convection in the closed space. In order to get the precise electric field in consideration of this effect, it is necessary to comprehend the flow field in the space. In this study, the steam cleaning of cargo-holds of a tanker is used as an example. The flow field in a rectangular space is numerically calculated using several flow models. Then, the unsteady electric field, taking into consideration the mobility of charge, is obtained numerically and compared with experimental data obtained by the authors. As a result, it became clear that the mobility of charge is an important factor in determining the electric field in the closed space, and the accuracy of the safety evaluation for the avoidance of electrostatic accidents could be improved by considering the effect.

A practical excimer laser-based cleaning tool for removal of surface contaminants

A laser-cleaning tool capable of removing surface contaminants such as submicron-sized particulates and organic films has been constructed and implemented in practical use. An industrial-grade KrF excimer laser is utilized to irradiate the solid surface to be cleaned. The nanosecond-pulsed laser irradiation, shortly after the deposition of a thin liquid film on the surface, induces explosive vaporization of the liquid and removal of particulates (steam cleaning). The ultraviolet (UV) irradiation also causes ablative photodecomposition of organic film contaminants on the surface (dry cleaning). Hence, cleaning can best be done with the combination of these two laser-cleaning modes. The excimer laser cleaning tool is constructed with an aim toward practical use: It includes a computer-controlled laser beam scanning system and a stable liquid film deposition unit, providing a cleaning rate of over 200 cm /min. Semiconductor, metal, and ceramic sample surfaces, contaminated with 1-/spl mu/m sized alumina particles and micron-thick epoxy films, are tested by laser cleaning. The effectiveness of laser cleaning is compared with ultrasonic technique. The cleaning strategy and the probability of thermal damage due to laser cleaning are discussed. >

Microbial Decontamination of Ventilation Systems

The American Conference of Governmental Industrial Hygienists (ACGIH) has issued a number of recommendations aimed at preventing abnormally high levels of bioaerosols. These include the elimination of stagnant water, microbial substrates, and microbial growth centres in ventilation systems, and the implementation of effective maintenance programmes. Disinfection tech niques (e.g., HEPA vacuuming, hypochlorite disinfection, and steam cleaning) are capable of eliminating microbial substrates and growth centres from ducts and other contaminated surfaces, but there is no information in the scientific literature on the optimum frequency of these operations. This study evaluated a number of corrective measures aimed at reducing aeromicrobial flora (bacte ria and saprophytic moulds). Samples of inside and outside air were taken at a laundry serving 30 hospitals. The outside air and that from 3 ventilation sys tems was sampled using a Burkard (Jet Spore) sampler, while an Andersen N-6 sampler was used to gather air samples at 6 workstations. Four 1-day sampling surveys were performed; in each case, samples were taken at least twice a day. In the first survey, carried out in June 1988, the contamination of outside air was found to differ significantly (p ≤ 0.05) from that of the air at some of the workstations, both qualitatively and quantitatively. The same workstations were re-evaluated in December 1988, 2 months after the ventilation system had been disinfected with hypochlorites and the operating conditions modi fied. No significant differences, either qualitative or quantitative, were observed between inside and outside air. The third sampling survey was undertaken in September 1989, 2 weeks after a specialized firm had per formed a complete disinfection of the system and ducts (HEPA vacuuming, steam cleaning, and disinfection with dilute hypochlorites). Visual inspection of the workplace and the ventilation system, now operating under normal con ditions, was also performed, in keeping with ACGIH recommendations. No significant difference was observed between inside and outside air. A 4th sur vey was conducted 8 months later, in May 1990, to verify the frequency of maintenance operations. Again, no significant differences were observed between inside and outside air. Ventilation systems should be disinfected before use, i.e., in the spring and autumn for air-conditioning units and heat ing units, respectively. The frequency of maintenance operations should be established on the basis of visual inspection.

Immunoassay of peanut allergens in food-processing materials and finished foods

To quantitate trace amounts of peanut allergens in food-processing materials and finished foods, we established a solid-phase radioimmunoassay inhibition using pooled sera from five peanut-sensitive subjects and a roasted peanut-meal extract covalently linked to polyacrylamide beads. Test samples were extracted, dialyzed, lyophilized, and reconstituted at 10 to 225 mg of dry weight per milliliter concentrations. The peanut-allergen content of test samples was expressed relative to a reference extract of roasted peanut meal that was assigned an arbitrary potency of 100,000 U/ml. In confectionery products spiked with varying quantities of peanut (0.7% to 0.0175%), the recovery of peanut allergen ranged from 31% to 94%. The sensitivity of the assay was 2.5 U/mg of dry weight from these samples (0.00875% peanut). Peanut allergens were undetectable in virgin vegetable oil used to roast peanuts, but 600 to 7600 U/mg of dry weight were present in oil after varying periods of use. The allergen content of used oil was reduced to 8 U/mg of dry weight by filtration and steam cleaning. The availability of such assays provides a means of monitoring finished food products for potential allergens. This monitoring in turn will provide the means to correlate symptoms experienced by sensitive patients with the exact quantity of allergen ingested. At the present time, there is little information on the quantities of ingested peanut allergen that pose risks to peanut-sensitive subjects.

Decontamination of Three Mile Island Unit 2

This compendium of previously published works, supplemented with discussion based on current perspective, summarizes the methods and equipment employed to decontaminate Three Mile Island Unit 2 from the accident of March 28, 1979 through May 1988. Early decontamination efforts are described to clarify the lessons learned from these activities when viewed from the present perspective. New developments in conventional technology, such as hydrolasers and new technologies for decontamination operations, such as steam cleaning, vacuuming, ultra-high-pressure waterjets, and remotely operated vehicles, are discussed.

Coccidiosis in Swine

It is clear that although the clinical history, pathologic lesions, and endogenous stage life cycle of I. suis are well understood, the epidemiology of this parasite is not understood or is misunderstood. Consequently, treatment of individual piglets and prophylactic use of coccidiostats in sows have not been consistently rewarding. The best control at present is achieved through use of extensive sanitation, particularly steam cleaning. The incidence of clinical coccidiosis in piglets continues to be a major component (approximately 20 per cent) in the differential etiology of scours in baby pigs.

PROBLEMS ASSOCIATED WITH EXTERNAL CLEANING OF AN HISTORIC MASONRY BUILDING IN PERTH, WESTERN AUSTRALIA

AbstractAn account of moisture and salt penetration following steam cleaning of a brick and limestone building in an urban environment is given. The salt efflorescence on the inside walls was hydrated sodium sulphate and the origin of this is discussed and conclusions presented which should help prevent future problems.

The Use of a Steam Cleaning Lance to Clean Laboratory Equipment

The Use of a Steam Cleaning Lance to Clean Laboratory Equipment

Chemical Surface Preparation of Steel Prior to Painting★

Abstract The proper surface preparation of metal prior to painting is becoming more and more important to industry. Experience has proven that a properly prepared surface will greatly increase the life of a paint system and the product and reduce maintenance costs. Advantages and disadvantages of various types of cleaning are listed. Methods discussed include solvent cleaning, alkali cleaning, emulsifiable solvent cleaning, steam cleaning, and acid cleaning. Other topics covered include pickling, the treating of pickled metal, the use of inhibitors in pickling, and the use of phosphate coatings. 5.9.2