Hydrostatic spraying

Hydrostatic Spraying (Airless Spraying) Electrostatic Spraying Powder Coating... 

Water resistance test methods include AATCC 127 (hydrostatic pressure test), AATCC 42 (impact penetration test), and AATCC 35 (rain test). In the hydrostatic pressure test, a sample is subjected to a column of increasing water pressure until leakage occurs. The impact penetration test requires water to be sprayed on the taut surface of a fabric sample from a height of two feet. The fabric is backed by a blotter of predeterrnined weight, which is reweighed after water penetration. The rain test is similar in principle to the impact penetration test. 

The rain test simulates the effects of rainfaU the hydrostatic head on the spray controls the intensity of spraying. The repeUency is rated by the weight of water that penetrates the fabric and is absorbed by a blotter mounted behind the fabric at a specific intensity of spraying (AATCC Test Methods 35 and 42 INDA Standard Test 80.2-92). 

Ashland admitted that Uie usual testing procedures were not employed before putting tlie tank into service. Hydrostatic testing is recommended by the American Petroleum Institute, but pumps large enough to gel water to the lop of tlie lank were not tnailable at the site. An alternate procedure was performed in which the lank was sprayed with diesel fuel and subjected to a vacuum. However, the lank was not inspected by any outside agency prior to use. 

Water Spray Flushing Hydrostatic test Flow test 15, 16... 

Water sprays from monitor nozzles and hose lines can be used for vapor mitigation. Tests have been conducted in which monitor nozzles and hose lines have been used to create a chimney effect through which the gas is forced upward and dispersed at a high elevation (Beresford, 1981). Application techniques and flow rates are facility-, installation-, and material-specific. Careful planning, analyses, and testing should be conducted prior to deciding on the use of a mobile water spray as a proven means of mitigation. Preventive maintenance of this equipment is key to reliable operation. Hose lines, typically, are hydrostatically tested annually. Flow tests should also be conducted periodically. 

The treated fabric, backed by a weighed piece of blotter paper, is sprayed with water under constant hydrostatic pressure for 5 min. The weight gain of the paper after the test is recorded. This test requires a special apparatus. 

AATCC Test Method 35 -2000 " is designed to simulate a rain event. A special apparatus is used to hold the 20 x 20 cm fabric sample in a vertical position backed by a weighed piece of blotter paper. The fabric face is sprayed with water under constant hydrostatic pressure for 5 min and the blotter paper reweighed. The increase in weight of the backing paper is a measure of the resistance of the fabric to penetration by the simulated rain. 

In a spraying process, a liquid is forced through an orifice (the spray nozzle) to form droplets by the application of hydrostatic pressure. The effect of surfactants and/or polymers on the droplet size spectrum of a spray can be described in terms of their effects on the surface tension. Since surfactants lower the surface tension of the liquid, one would expect that their presence in the spray solution would result in the formation of smaller droplets. However, when considering the role of surfactants in droplet formation, one should consider the dynamics of surfactant adsorption at the air/liquid interface. In a spraying process, a fresh liquid surface is continuously being formed. The surface tension of this... 

The hold-up of the dispersed phase was determined by several techniques as there is no particular method which is reliable in all cases. In spray columns the hydrostatic method gives good results but this was not applicable in agitated columns. A comparison of different possible methods and their applicability is given in Table 2. 

Figure 3 Example of spray column with measuring points MS 1 to 6 Separate sampling of both phases for determination of concentration profiles, ES-OS ports for hold-up measurement by hydrostatic method, tracer injection, FA,FB windows for photographic determination of drop size.

In a spraying process, a liquid is forced through an orifice (the spray nozzle) to form droplets by application of a hydrostatic pressure. Before describing what happens during spraying, it is beneficial to consider the processes that occur when a drop is formed at various time intervals. If the time to form a drop is large (greater say than 1 minute), the volume of the drop depends on the properties of the liquid, such as its surface tension and the dimensions of the orifice, but is in-... 

Global adoption of Association for the Advancement of Medical Instrumentation (AAMI) and European standards for surgical drapes and gowns has changed the medical barrier nonwoven performance requirements. For example, while AAMI Level 2 protection requires a spray impact of less than 1 g and a statistically significant minimum of 20 cm of hydrostatic head, AAMI Level 3 requires these fabrics to have a spray impact test result of less than 1 g and a minimum 50-cm hydrostatic head based... 

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