Splashing threshold

Figure 3.31. Splashing threshold for surface impact of a droplet train.

L. Randy, G. Vander Wall, G. M. Berger, S. D. Mozes The combined influence of a rough surface and thin fluid film upon the splashing threshold and splash dynamics of a droplet impacting onto them, Exp. Fluids, 40, 23-32 (2006). 

Health Hazards Information - Recommended Personal Protective Equipment Face shield to avoid splash Symptoms Following Exposure Very high vapor concentrations irritate eyes and upper respiratory tract. Continued contact with skin may cause irritation General Treatment for Exposure EYES immediately flush with plenty of water for at least 15 min. get medical attention. SKIN flush with water wash with soap and water Toxicity by Inhalation (ThresholdLimit Value) QO ppm Short-Term Inhalation Limits Data not available Toxicity by Ingestion Grade 2, LDjq 0.5-5 g/kg Late Toxicity None Vapor (Gas) Irritant Characteristics Vapor is moderately irritating such that personnel will not usually tolerate moderate or high vapor concentrations Uq or Solid Irritant Characteristics Liquid may irritate skin Odor Threshold Data not available. 

If the fluid dynamic conditions of a droplet are within the spreading regime, i.e., below the threshold curve in the We-Oh map, liquid splashing and ejection from the impact surface can be eliminated. The corresponding threshold velocity can be written as ... 

The splashing criterion derived by Stow and Hadfieldl396 showed that the threshold velocity may be estimated by ... 

Yarin and Weiss[357] also determined the number and size of secondary droplets, as well as the total ejected mass during splashing. Their experimental observations by means of a computer-aided charge-coupled-device camera and video printer showed that the dependence of the critical impact velocity, at which splashing initiates, on the physical properties (density, viscosity, and surface tension) and the frequency of the droplet train is universal, and the threshold velocity may be estimated by ... 

Exposure to high concentrations may cause tracheobronchitis and pulmonary edema. The irritation threshold in humans is 0.2 5-0.5 ppm, and concentrations above Ippm are extremely irritating to all mucous membranes within 5 minutes. Fatalities have been reported at levels as low as 10ppm, and 150 ppm was lethal after 10 minutes. The violent irritant effect usually prevents chronic toxicity in humans. Skin contact causes irritation, burns, and epidermal necrosis." Eye splashes cause corneal damage, palpebral edema, blepharoconjunctivitis, and fibrinous or purulent discharge. ... 

Eye splashes cause marked conjunctivitis and may result in permanent corneal damage. The lacrimation threshold ranges from 0.3 to... 

The TLV (threshold limit value) for HCN is 11 mg/m or 10 ppm[l33). These limits include the potential contribution of skin absorption to the overall exposure. Proper gloves should be worn when handling dry sodium cyanide. Rubber gloves and splash-proof goggles should also be worn when substantial amounts of sodium cyanide solution are used. All reaction equipment in which cyanides are used or produced should be placed in well-ventilated hoods, and it should be determined immediately whether anyone has been exposed to cyanide vapors or liquid splashing 134-136). 

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