Development of a Method to Study Evaporation of a Volatile Solvent in an Isolated Subsurface Structure: A Practical Exercise in Risk Minimization

Thomas Neil McManus; Ana Rosa; Assed Haddad

doi:10.3390/infrastructures5080068

Development of a Method to Study Evaporation of a Volatile Solvent in an Isolated Subsurface Structure: A Practical Exercise in Risk Minimization

Infrastructures ◽

10.3390/infrastructures5080068 ◽

2020 ◽

Vol 5 (8) ◽

pp. 68

Author(s):

Thomas Neil McManus ◽

Ana Rosa ◽

Assed Haddad

Keyword(s):

Evaporation Rate ◽

Personal Exposure ◽

Confined Space ◽

Subsurface Structure ◽

Risk Minimization ◽

Confirmatory Testing ◽

Paper Towel ◽

Chemical Products ◽

Lower Flammable Limit

This article describes development and confirmatory testing of a method to study the evaporation of a volatile solvent containing ignitable ingredients in an isolated subsurface structure, a type of confined space. Accidental spillage and surreptitious disposal of chemical products in streets create a risk of fire and explosions in these structures. Development of the method included consideration about instrument safety; personal exposure; volume of the structure (2.5 m3); evaporation rate; temperature of the airspace; and number of opening(s) in the manhole cover. Confirmatory testing utilized 10 mL of lacquer thinner (60% to 80% toluene, 10% to 20% methylethyl ketone (MEK), 5% to 10% methanol and 1% to 9% acetone) on a wetted paper towel positioned near the bottom of the structure. This methodology produced a maximum of 2150 ppm of ‘isobutylene units’ on a PID (PhotoIonization sensor) positioned about 15 cm above the sample. This concentration corresponds to about 1140 ppm of toluene (less than 10% of the Lower Flammable Limit of 12,700 ppm). This method offers a stable, safe platform for study of the process. Evaporation of solvent and exchange between the external atmosphere and the airspace regulate the concentration of vapor, which can typically persist for 24 to 48 h.

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Unusual Fast Evaporation From Nanoholes

Volume 7: Fluids and Heat Transfer, Parts A, B, C, and D ◽

10.1115/imece2012-87147 ◽

2012 ◽

Cited By ~ 1

Author(s):

Zhi Huang ◽

Yuanchen Hu ◽

Kang Liu ◽

Xuejiao Hu

Keyword(s):

Water Surface ◽

Evaporation Rate ◽

Physical Phenomenon ◽

Gravimetric Method ◽

Industrial Applications ◽

Water Evaporation ◽

Good Prediction ◽

Confined Space ◽

Affecting Factors ◽

Air Conditioning Systems

Water evaporation is an important physical phenomenon that occurs in nature and several industrial applications such as food drying processes, cooling in air-conditioning systems and desalination. In all these systems, it is necessary to have a good prediction and control of evaporation rate as a function of various system parameters. Attempts to understand the affecting factors have mostly focus on the flow rates of gas or water streams, relative humidity of the air, presence of dissolved or suspended material in the water, temperatures of the air and water streams. However, as water surface partially covered (less surface area) is generally thought to have lower evaporation rate, little notice has ever put on it. Here we consider the evaporation case of water surface covered with nano-through-hole lid (NHL) of which the radius size is nearly equal to the average free path of the vapor. Using a gravimetric method, we experimentally measured the evaporation rate of water at the orifice of the nano-holes. The results indicate that the evaporation rate is 1–6 times faster than the non-sheltered water surface with the same liquid area. Moreover, with the porosity of the lid decreasing, the evaporation rate per unit area increases. A theoretical model is developed for this novel phenomenon from the view of molecular dynamics during evaporation and vapor diffusion. We envision that this finding may have new inspirations on phase change phenomenon in nano-confined space and put forward one new way for promoting evaporation of liquid.

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Ventilation of an Isolated Subsurface Structure Induced by Natural Forces

Infrastructures ◽

10.3390/infrastructures4020033 ◽

2019 ◽

Vol 4 (2) ◽

pp. 33 ◽

Cited By ~ 4

Author(s):

Thomas Neil McManus ◽

Assed Haddad

Keyword(s):

Gasoline Engine ◽

Operating Time ◽

Zero Order ◽

Statistical Testing ◽

Order Kinetic ◽

Confined Space ◽

Subsurface Structure ◽

Different Seasons ◽

Cast Concrete ◽

Isolated Structures

The subsurface infrastructure comprises many types of isolated structures, a type of confined space. This study reports on the effect of engine operating time, number/area and spacing of openings in the manhole cover, and operation during different seasons on ventilation of a subsurface, isolated, pre-cast concrete chamber through opening(s) in the manhole cover. Carbon monoxide (CO) emitted by a small gasoline engine reached 800 ppm in 30 s at the start of testing. Ventilation occurred continuously. Generally, the concentration of CO reported by instruments located at different heights was the same for the same moment in time, suggestive of a rapidly well-mixed atmosphere. Mathematical modelling suggested that ventilation occurred through a zero-order kinetic process. Statistical testing suggested that optimization of ventilation is possible through design modifications such as change in the number/area/shape/spacing/geometric arrangement of openings in the manhole cover. Optimizing the rate of ventilation induced by natural forces during the interval between entries will reduce the risk of explosion of the confined atmosphere and overexposure of workers when opening the manhole cover to prepare for entry. This improvement will have immense implications to safety worldwide.

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Hole Formation in Gold Films

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100095807 ◽

1972 ◽

Vol 30 ◽

pp. 510-511

Author(s):

R. W. Vook ◽

R. Cook ◽

R. Ziemer

Keyword(s):

Deposition Rate ◽

Quartz Crystal ◽

Evaporation Rate ◽

Gold Films ◽

Hole Density ◽

Hole Formation ◽

Microscope Slide ◽

Crystal Film ◽

Glass Microscope Slide ◽

Glass Microscope

During recent experiments on Au films, a qualitative correlation between hole formation and deposition rate was observed. These early studies were concerned with films 80 to 1000A thick deposited on glass at -185°C and annealed at 170°C. In the present studies this earlier work was made quantitative. Deposition rates varying between 5 and 700 A/min were used. The effects of deposition rate on hole density for two films 300 and 700A thick were investigated.Au was evaporated from an outgassed W filament located 10 cm from a glass microscope slide substrate and a quartz crystal film thickness monitor. A shutter separating the filament from the substrate and monitor made it possible to obtain a constant evaporation rate before initiating deposition. The pressure was reduced to less than 1 x 10-6 torr prior to cooling the substrate with liquid nitrogen. The substrate was cooled in 15 minutes during which the pressure continued to drop to the mid 10-7 torr range, where deposition was begun.

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