Rapid Pressurization That Does Not Allow Gas Absorption by Liquid.

DOE-HDBK-3010-94

3.0 Liquids; Aqueous Solutions

material in the respirable size range of 1.0 appears conservative. For the UNH

(higher density liquid, ~1.3 g/cm3), a bounding ARF of 1E-3 (100 ml UNH at

500 psi) with a fraction of the airborne material in the respirable size fraction of 0.4

appears conservative. The "median" values for the uranine ARF and RF are 3E-4

and 0.9 and 2E-4 and 0.3 for UNH. The average values for uranine are ARF and RF

of 5E-4 and 0.9 and 3E-4 and 0.5 for UNH.

For the sake of simplicity, a gross density distinction is made for determining which

ARF and RF values to use. Any solution containing heavy metal salts where the

liquid alone has a density in excess of ~ 1.2 g/cm3 is considered a "concentrated

heavy metal solution" for assigning ARF and RF values (i.e., 1E-3 and 0.4). Any

solution containing heavy metal salts where the solution alone has a density less than

~ 1.2 g/cm3 is considered an "aqueous solution" for assigning ARF and RF values

(i.e, 2E-3 and 1.0).

B. R ap id P ressurization T h at D oes N ot A llow G as A b s orp tion b y L iq u id .

If a pressurized vessel vents, liquid contents can be suspended as droplets formed by

turbulent shear stress on the liquid surface. If flow across the liquid is perpendicular

to the liquid surface (i.e., entire crown of vessel is lost), the gases pass directly to the

atmosphere and has little impact on the surface. Some small fraction of liquid may be

suspended by the negative phase of the impulse due to the release of normally

dissolved gases in the liquid.

If vent diameter is small and flow is low, little stress is created on the liquid surface.

If the vent size is adequate to generate flows resulting in turbulence on the liquid

surface, liquid can be suspended by drop formation. In the experimental study of

stratified two-phase flow reported by Shrock et al. (August 1987), a determinant

parameter for the release of airborne droplets was Critical Freeboard Height. This is

the height from the gas-liquid interface to the break center where gas or liquid pull

through begins. Equation 5.7 in the study report is:

[V/gD][(dg/∆P)0.5]

0.395(hb/D)2.5

(3-6)

where:

gas velocity

gravitational acceleration, 980 cm/s2

diameter of vent

density of gas at saturation

∆P

pressure differential

Critical Freeboard Height.

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