Sheng-Hung Wu

Thermal runaway analyses for two organic peroxides with H2O and dry fire-extinguishing chemicals by DSC and VSP2

In recent years, organic peroxides, including methyl ethyl ketone peroxide (MEKPO) and cumene hydroperoxide (CHP), have often caused thermal runaway reactions, fires, and thermal explosions worldwide. Under normal circumstances, H2O and dry fire-extinguishing chemicals are often employed to eliminate fire situations. We evaluated the thermal runaway reaction for MEKPO and CHP mixed with H2O and dry fire-extinguishing chemicals by differential scanning calorimetry, and thermal runaway reaction for CHP mixed with dry fire-extinguishing chemicals by vent sizing package 2. The results showed that ABC dry chemical, BC dry chemical, and XBC dry chemical all caused the decomposition of MEKPO to occur at lower onset temperature and H2O caused the ΔHd of MEKPO to become higher. On the other hand, H2O and XBC dry chemical induced the decomposition of CHP to occur at lower onset temperature as well as lower thermal explosion temperature. The maximum of self-heating rate ((dT/dt)max) and the maximum pressure-rise rate ((dP/dt)max) of CHP mixed with dry fire-extinguishing chemicals were measured lower than CHP alone. The results indicated that MEKPO and CHP are highly hazardous when mixed with H2O and some dry fire-extinguishing chemicals. In view of loss prevention, the results can be useful references for fire fighters dealing with thermal upsets in chemical plants.

Improving the indoor air quality of respiratory type of medical facility by zeolite filtering

This study investigated the indoor air quality (IAQ) conditions of carbon dioxide (CO2), carbon monoxide (CO), ozone (O3), formaldehyde (HCHO), total volatile organic compounds (TVOCs), and bio-aerosols (bacteria and fungi) in a respiratory type of medical facility in Chia-Yi County in southern Taiwan. Among those IAQ conditions, the concentrations of CO, O3, and HCHO exceeded the regulation values of the Taiwan Environmental Protection Administration (EPA) mostly in the morning. The concentrations of bacteria and fungi did not exceed the regulation values but still posed potential health and environment problems for workers, patients, and visitors. Therefore, self-made silver-coated zeolite (AgZ) was used as a filter material in air cleaners to remove bio-aerosols in the respiratory care ward (RCW), and the removals were still effective after 120 hr. The cumulative bio-aerosol removals for bacteria and fungi were 900 and 1,088 colony-forming units (CFU) g−1 after 24 hr and were above 3,100 and 2,700 CFU g−1 after 120 hr. From the research results, it is suggested that AgZ filtering could be used as a feasible engineering measure for hospitals to control their bacteria and fungi parameters in IAQ management. Hospitals should maintain their environmental management and monitoring programs and use different engineering measures to improve different IAQ parameters. Implications: This study investigated the IAQ conditions in the field at a hospital in Chia-Yi County in southern Taiwan. Although concentrations of most parameters were still within the regulation values, the concentrations of CO, O3, and HCHO were partially exceeded. We propose a method using an air cleaner with silver-coated zeolite (AgZ) as a possible engineering measure, and there were effective reductions of bacteria and fungi to lower levels with antibacterial effects after 120 hr. Furthermore, this study implies that hospitals should continuously maintain environmental monitoring programs and adopt optimal engineering measures for different needs.