Drain Pan Research Articles

Leak Monitoring in Split Duct Air Conditioner Based on Internet of Things

Water accumulation in air conditioning (AC) drain pans can lead to corrosion and subsequent leaks, impacting AC system performance. This study focuses on implementing a monitoring system to track water levels and promptly discharge water to prevent corrosion. Using a research and development approach, the study evaluated the water level sensor's performance in measuring water levels and the pump's effectiveness in discharging water at specific levels, ensuring overall system reliability. The system utilized the NodeMCU ESP8266 microcontroller, a water level sensor, an LCD I2C 16x2 display, and Blynk as a smartphone-based monitoring platform. The findings demonstrated the effective functionality of the device in evacuating accumulated water from the AC evaporator. This was achieved through the activation of a water pump when the water level reached a threshold of 2 cm, thereby preventing potential leakage in the air conditioner's storage gutter.

Outbreak of Burkholderia multivorans among patients at two acute-care hospitals in California, August 2021–July 2022

Background:Burkholderia multivorans are gram-negative bacteria typically found in water and soil. B. multivorans outbreaks among patients without cystic fibrosis have been associated with exposure to contaminated medical devices or nonsterile aqueous products. Acquisition can also occur from exposure to environmental reservoirs like sinks or other hospital water sources. We describe an outbreak of B. multivorans among hospitalized patients without cystic fibrosis at 2 hospitals within the same healthcare system in California (hospitals A and B) between August 2021 and July 2022. Methods: We defined confirmed case patients as patients without cystic fibrosis hospitalized at hospital A or hospital B between January 2020 to July 2022 with B. multivorans isolated from any body site matching the outbreak strain. We reviewed medical records to describe case patients and to identify common exposures. We evaluated infection control practices and interviewed staff to detect exposures to nonsterile water. Select samples from water, ice, drains, and sink splash zone surfaces were collected and cultured for B. multivorans in March 2022 and July 2022 from both hospitals. Common aqueous products used among case patients were tested for B. multivorans. Genetic relatedness between clinical and environmental samples was determined using random amplified polymorphic DNA (RAPD) and repetitive extragenic palindromic polymerase chain reaction (Rep-PCR). Results: We identified 23 confirmed case patients; 20 (87%) of these were identified at an intensive care unit (ICU) in hospital A. B. multivorans was isolated from respiratory sources in 18 cases (78%). We observed medication preparation items, gloves, and patient care items stored within sink splash zones in ICU medication preparation rooms and patient rooms. Nonsterile water and ice were used for bed baths, swallow evaluations, and ice packs. B. multivorans was cultured from ice and water dispensed from an 11-year-old ice machine in the ICU at hospital A in March 2022 but no other water sources. Additional testing in July 2022 yielded B. multivorans from ice and a drain pan from a new ice machine in the same ICU location at hospital A. All products were negative. Clinical and environmental isolates were the same strain by RAPD and Rep-PCR. Conclusions: The use of nonsterile water and ice from a contaminated ice machine contributed to this outbreak. Water-related fixtures can serve as reservoirs for Burkholderia, posing infection risk to hospitalized and immunocompromised patients. During outbreaks of water-related organisms, such as B. multivorans , nonsterile water and ice use should be investigated as potential sources of transmission and other options should be considered, especially for critically ill patients.Disclosures: None

Low-cost crushed-rock heat storage with oil or salt heat transfer

The demand for variable electricity and heat is met by fossil-fuel power plants because the power plant capital costs and the cost of storing fossil fuels are low. A low-carbon economy requires replacement of the storage function of fossil fuels to provide variable heat and electricity as needed. The Crushed Rock Ultra-large Stored Heat (CRUSH) system is a new technology with the goal to provide heat storage at an incremental capital cost of $2–4/kWh at scales of 10 s to 100 s of GWhs that enables economic daily to multi-week storage. CRUSH can be coupled to nuclear power plants, concentrated solar power (CSP) plants and thermal energy batteries to provide variable electricity and heat on demand. Sensible heat is stored in crushed rock—the lowest-cost heat-storage material. Heat is transferred to and from the crushed rock using nitrate salt or heat-transfer oils but these fluids do not store heat. Heat from a nuclear reactor, CSP plant or conversion of low-price electricity into heat is used to heat the salt or oil. The hot fluid is poured over the crushed rock, trickles downward by gravity through the rock, heats the rock and is collected by the drain pans under the crushed rock. To recover heat cold salt or oil is poured over hot crushed rock, trickles down by gravity while being heated and is collected by the drain pans under the crushed rock. The system design and engineering trade-offs are described. The technology is in the early stages of development.

Thermal performance of a suspended ceiling fin heat transfer panel with drain pan

Radiant air conditioning systems provide better comfort and energy efficiency than air conditioning systems based on forced convection. In order to prevent condensation, the surface temperature of the radiant heat transfer component in conventional radiant air conditioning must be maintained above the dew point temperature, resulting in insufficient cooling capacity. In this paper, a new type of suspended ceiling fin heat transfer panel with a drain pan is proposed to achieve a large temperature difference for the cooling/heating supply. This panel has the characteristics of large heat flux per unit area, sufficient cooling capacity, and simplified heat exchange system. The research results show that the heat flux of the fin heat transfer panel accounts for 90%. In a comparison of the suspended ceiling radiant panels of different structures, the suspended ceiling fin heat transfer panel may be used with a refrigerant with a lower temperature relative to the other two structures and has great potential to improve heat flux, which can reduce the installation area of indoor radiant panels. Finally, the structure of the fin heat transfer panel was optimised. When the fin spacing of the fin heat transfer panel was 5.2 mm, the cooling/heating capacity of the fins was improved by a factor of 1.5 compared to the panel with the original spacing of 1.8 mm, and the metal material required was reduced to approximately 33% of the total. These results serve as a theoretical and practical reference for the study of such air conditioning systems.

Influence of air conditioning and mechanical ventilation (ACMV) systems on indoor microbial aerosols

It is by now well established that most humans spend 70%–90% of their time in the mechanically ventilated buildings, in which the air conditioning and ventilation (ACMV) systems are commonly employed to provide fresh and clean air for indoor occupants. The air supplied to indoor environments inevitably passes over ACMV system and the interaction between the air and the ACMV surfaces can modify microbial air quality. Therefore, understanding how the ACMV influence biological aerosols can contribute to more incisive research to characterize indoor microbiology and associated health consequences. Such understanding is also essential for designing effective engineering controls to reduce bioaerosol exposure risks. In this systematic review, the content is organized into two main sections. In Part one—Influence of ACMV major components on indoor bioaerosol, commonly means the components could directly reduce or increase the indoor microbial bioaerosol concentrations. Except outdoor bioaerosols, the major components on the ACMV system could be also potential microbe’s resources. In this part, we summarize how do the major components, such as filters, heat exchanger, cooling tower and ventilation ducts, influence indoor bioaerosols. In the meantime, we emphasized an inspirational consideration that the ACMV system as a direct pathway could also spread the existing indoor microbes into other more indoor environment. Part two (Influence to indoor bioaerosol by operation mode of ACMV) summarizes available information on many important processes of ACMV that could affect the concentrations and fates of indoor bioaerosol. This section begins by reviewing the state of knowledge regarding the factors related to the components themselves (design, material); following with the factors related to the physical and chemical environment around the components (temperature, relative humidity, and airflow). Then, the article proceeds to discuss several additional processes that can affect indoor bioaerosol levels: controlling the relative humidity of the ACMV system, selection of the appropriate ventilation rate, periodically cleaning the components such as filters and ventilation ducts, and removing moisture from the drain pan and heat exchanger accordingly. In the conclusion, important challenges facing further studies are described along with several opportunities for near-term progress advancing knowledge about indoor microbial aerosols along with the interaction of ACMV system. Such progress is fundamental to efforts to better understand how the micro biome of indoor environments interacts with human health and wellbeing.

Hiding in Plain Sight: Contaminated Ice Machines Are a Potential Source for Dissemination of Gram-Negative Bacteria and Candida Species in Healthcare Facilities.

BACKGROUND Contaminated ice machines have been linked to transmission of pathogens in healthcare facilities. OBJECTIVE To determine the frequency and sites of contamination of ice machines in multiple healthcare facilities and to investigate potential mechanisms of microorganism dispersal from contaminated ice machines to patients. DESIGN Multicenter culture survey and simulation study. SETTING The study took place in 5 hospitals and 2 nursing homes in northeastern Ohio. METHODS We cultured multiple sites on ice machines from patient care areas. To investigate potential mechanisms of microbial dispersal from contaminated ice machines, we observed the use of ice machines and conducted simulations using a fluorescent tracer and cultures. RESULTS Samples from 64 ice machines in the 5 hospitals and 2 nursing homes (range, 3-16 per facility) were cultured. Gram-negative bacilli and/or Candida spp were recovered from 100% of drain pans, 52% of ice and/or water chutes, and 72% of drain-pan grilles. During the operation of ice machines, ice often fell through the grille, resulting in splattering, with dispersal of contaminated water from the drain pan to the drain-pan grille, cups, and the hands of those using the ice machine. Contamination of the inner surface of the ice chute resulted in contamination of ice cubes exiting the chute. CONCLUSIONS Our findings demonstrate that ice machines in healthcare facilities are often contaminated with gram-negative bacilli and Candida species, and provide a potential mechanism by which these organisms may be dispersed. Effective interventions are needed to reduce the risk of dissemination of pathogenic organisms from ice machines. Infect Control Hosp Epidemiol 2018;39:253-258.

Risk assessment and quality improvement of liquid waste management in Taiwan University chemical laboratories

The policy of establishing new universities across Taiwan has led to an increase in the number of universities, and many schools have constructed new laboratories to meet students’ academic needs. In recent years, there has been an increase in the number of laboratory accidents from the liquid waste in universities. Therefore, how to build a safety system for laboratory liquid waste disposal has become an important issue in the environmental protection, safety, and hygiene of all universities. This study identifies the risk factors of liquid waste disposal and presents an agenda for practices to laboratory managers. An expert questionnaire is adopted to probe into the risk priority procedures of liquid waste disposal; then, the fuzzy theory-based FMEA method and the traditional FMEA method are employed to analyze and improve the procedures for liquid waste disposal. According to the research results, the fuzzy FMEA method is the most effective, and the top 10 potential disabling factors are prioritized for improvement according to the risk priority number (RNP), including “Unclear classification”, “Gathering liquid waste without a funnel or a drain pan”, “Lack of a clearance and transport contract”, “Liquid waste spill during delivery”, “Spill over”, “Decentralized storage”, “Calculating weight in the wrong way”, “Compatibility between the container material and the liquid waste”, “Lack of dumping and disposal tools”, and “Lack of a clear labels for liquid waste containers”. After tracking improvements, the overall improvement rate rose to 60.2%.

Development of a Fungal Biosensor for Field Verifying the Surface Disinfection of Ultraviolet Germicidal Irradiation Systems for Air Handling Units

This study developed a fungal biosensor to verify the germicidal effect of ultraviolet germicidal irradiation (UVGI) systems in the field from a biosensor originally developed to assess indoor climate. A UVC ray was irradiated on the fungal spores of the biosensors at various doses, and the differences in hyphal length after subsequent incubation were observed to verify the susceptibility of the fungal biosensor to C-band ultraviolet (UVC). The results showed reasonable correlations between UVC dosage and hyphal length. These fungal biosensors were thereafter attached to the coil and the drain pan of an air handling unit with a UVGI system installed and exposed to UVC for 1 h to test the effectiveness of the biosensors on the UVGI systems in the field. The hyphal lengths observed after incubation corresponded with UVC doses of 468–1620 J·m−2 at each sampling point as shown in the previous susceptibility experiments. The extended experiments to confirm the susceptibility of the fungal spores showed that the spores were more sensitive to UVC ray than those of the fungal biosensor and had similar susceptibility to the same UVC doses even at different UVC intensities.

Effects of salinity on eggplant (Solanum melongena L.) growth and evapotranspiration

AbstractThe effects of irrigation water salinity on eggplant growth, yield, water consumption and mineral matter accumulation in leaves and fruits were investigated with a greenhouse experiment. For this purpose, five saline irrigation waters with electrical conductivities of 1.5, 2.5, 3.5, 5.0, 7.0 dS m−1 and tap water as a control treatment were utilized. Throughout the experiment, the amounts of irrigation water to be applied were determined based on the weight changes of each pot. After irrigation the amount of drainage water volume was measured in drain pans placed underneath each pot. We calculated the plant water consumption from the water budget information. Threshold soil salinity and slope values of the yield response to soil salinity level were determined as <1.5 dS m−1 and 4.4 respectively for fruit yield and 6.7 dS m−1 and 3.7 for the vegetative dry weight. The fruit yield results revealed that eggplant was moderately sensitive to salinity. Plant water consumption and water use efficiency decreased with increasing salinity. The crop yield coefficient (Ky) was 2.3. Salinity caused a decrease in K content, and increased Cl content of leaves. Although mineral concentration of the leaves did respond to increased mineral concentration of irrigation water, mineral concentration of fruits did not. Copyright © 2008 John Wiley & Sons, Ltd.

Risk factors in heating, ventilating, and air-conditioning systems for occupant symptoms in US office buildings: the US EPA BASE study

Building-related symptoms in office workers worldwide are common, but of uncertain etiology. One cause may be contaminants related to characteristics of heating, ventilating, and air-conditioning (HVAC) systems. We analyzed data from 97 representative air-conditioned US office buildings in the Building Assessment and Survey Evaluation (BASE) study. Using logistic regression models with generalized estimating equations, we estimated odds ratios (OR) and 95% confidence intervals for associations between building-related symptom outcomes and HVAC characteristics. Outdoor air intakes less than 60 m above ground level were associated with significant increases in most symptoms: e.g. for upper respiratory symptoms, OR for intake heights 30 to 60 m, 0 to <30 m, and below ground level were 2.7, 2.0, and 2.1. Humidification systems with poor condition/maintenance were associated with significantly increased upper respiratory symptoms, eye symptoms, fatigue/difficulty concentrating, and skin symptoms, with OR = 1.5, 1.5, 1.7, and 1.6. Less frequent cleaning of cooling coils and drain pans was associated with significantly increased eye symptoms and headache, with OR = 1.7 and 1.6. Symptoms may be due to microbial exposures from poorly maintained ventilation systems and to greater levels of vehicular pollutants at air intakes nearer the ground level. Replication and explanation of these findings is needed. These findings support current beliefs that moisture-related HVAC components such as cooling coils and humidification systems, when poorly maintained, may be sources of contaminants that cause adverse health effects in occupants, even if we cannot yet identify or measure the causal exposures. While finding substantially elevated risks for poorly maintained humidification systems, relative to no humidification systems, the findings do not identify important (symptom) benefits from well-maintained humidification systems. Findings also provide an initial suggestion, needing corroboration, that outdoor air intakes lower than 18 stories in office buildings may be associated with substantial increases in many symptoms. If this is corroborated and linked to ground-level vehicle emissions, urban ventilation air intakes may need to be located as far above ground level as possible or to incorporate air cleaners that remove gaseous pollutants.

Indicators of Moisture and Ventilation System Contamination in U.S. Office Buildings as Risk Factors for Respiratory and Mucous Membrane Symptoms: Analyses of the EPA BASE Data

We assessed associations between indicators for moisture in office buildings and weekly, building-related lower respiratory and mucous membrane symptoms in office workers, using the U.S. EPA BASE data, collected in a representative sample of 100 U.S. office buildings. We estimated the strength of associations between the symptom outcomes and moisture indicators in multivariate logistic regression models as odds ratios (ORs) and 95% confidence intervals (CI), controlling for potential confounding factors and adjusting for correlation among workers in buildings. This analysis identified associations between building-related symptoms and several indicators of moisture or contamination in office buildings. One set of models showed almost a tripling of weekly building-related lower respiratory symptoms in association with lack of cleaning of the drip pans under air-conditioning cooling coils (OR [CI] = 2.8 (1.2–6.5)). Other models found that lack of cleaning of either drip pans or cooling coils was associated with increased mucous membrane symptoms (OR [CI] = 1.4 (1.1–1.9)). Slightly increased symptoms were also associated with other moisture indicators, especially mucous membrane symptoms and past water damage to building mechanical rooms (OR [CI] = 1.3 (1.0–1.7)). Overall, these findings suggest that the presence of moisture or contamination in ventilation systems or occupied spaces in office buildings may have adverse respiratory or irritant effects on workers. The analysis, however, failed to confirm several risks identified in a previous study, such as condition of drain pans or outdoor air intakes, and other hypothesized moisture risks. Studies with more rigorous measurement of environmental risks and health outcomes will be necessary to define moisture-related risks in buildings.

BUILDING-RELATED SYMPTOMS AMONG U.S. OFFICE WORKERS AND RISK FACTORS FOR MOISTURE AND CONTAMINATION

Introduction Moisture and other risks for indoor microbiologic growth have been associated with increased prevalence of symptoms in many studies. We assessed relationships between health symptoms in office workers and risk factors related to moisture and contamination, using data collected from a representative sample of 100 U.S. office buildings in the U.S. EPA BASE study. Methods Analyses assessed associations between three types of buildingrelated symptoms (defined as occurring at least weekly and improving when away from the building)-lower respiratory, mucous membrane, and neurologic-and risk factors for moisture or contamination in these office buildings. Multivariate logistic regression models were used to estimate the strength of associations for these risk factors as odds ratios (ORs) adjusted for personal-level potential confounding variables related to demographics, health, job, and workspace. Results A number of risk factors were associated significantly (e.g., 95% confidence limits excluded 1.0) in adjusted models with small to moderate increases in one or more symptom outcomes. Significantly elevated ORs for mucous membrane symptoms were associated with the following risk factors: presence of humidification system in good condition versus no system present (OR = 1.4); air handler inspection annually versus daily (OR = 1.6); current water damage in the building (OR = 1.2); and less than daily vacuuming in study space (OR = 1.2). Significantly elevated ORs for lower respiratory symptoms were associated with: air handler inspection annually versus daily (OR = 2.0); air handler inspection less than daily but at least semi-annually (OR = 1.6); less than daily cleaning of offices (1.7); and less than daily vacuuming of the study space (OR = 1.4). Only two statistically significant risk factors for neurologic symptoms were identified: presence of any humidification system versus none (OR = 1.3); and less than daily vacuuming of the study space (OR = 1.3). Dirty cooling coils, dirty or poorly draining drain pans, and standing water near outdoor air intakes were not identified as risk factors in these analyses, despite predictions based on previous findings elsewhere, except that very dirty cooling coils were associated with a statistically nonsignificant increase (OR = 1.3, 95% confidence interval = 0.9–2.1) in lower respiratory symptoms Conclusions These preliminary findings suggest that some factors indicating risks for moisture or contamination in office buildings may have adverse effects on respiratory or neurologic health of office workers. Expanded analyses are underway that will include in multivariate models additional potential confounders and risk factors, such as ventilation rate and indoor temperature. Future analyses will also assess risk in susceptible sub-groups such as previously diagnosed asthmatics.

The National Institute for Occupational Safety and Health Indoor Environmental Evaluation Experience. Part Three: Associations between Environmental Factors and Self-Reported Health Conditions

Abstract Associations between environmental factors and work-related health conditions were assessed using regression techniques with environmental and health data for 2435 respondents in 80 office buildings included in the National Institute for Occupational Safety and Health Health Hazard Evaluation program. The health conditions analyzed included two symptom groupings—multiple lower respiratory symptoms and multiple atopic symptoms—and the presence of asthma diagnosed after beginning work in the building. Four categories of environmental variables were included: heating, ventilation, and air conditioning (HVAC) system design; HVAC maintenance; building design; and building maintenance. Female gender and age over 40 years showed increased relative risks (RRs) for each health condition. In regression models adjusted for age and gender, RRs of multiple lower respiratory symptoms were increased for variables in the HVAC design and maintenance categories, with the highest RR for presence of debris inside the air intake [RR = 3.1, confidence interval (CI) = 1.8, 5.2] and for poor or no drainage from drain pans (RR = 3.0, CI = 1.7, 5.2). Elevated RRs of multiple atopic symptoms were found for variables in three of the four environmental categories, with the highest for presence of suspended ceiling panels (RR = 2.3, CI = 1.0, 5.5). The RR of asthma was highest if recent renovation with new drywall had been performed (RR = 2.5, CI = 1.4, 4.5). These data are from office spaces about which there was some level of occupant concern, and thus it may not be appropriate to use them to estimate the magnitude and distribution of symptoms found in all office spaces within U.S. buildings. Furthermore, the high degree of correlation among environmental variables makes it difficult to disentangle which are the most important predictors of work-related health conditions. The analysis is useful, however, for determining factors that may be associated with development of health conditions in the office environment and which might be considered in any building plan to reduce indoor air-related symptoms.

Heterotrophic bacteria in an air-handling system.

Heterotrophic bacteria from structural surfaces, drain pan water, and the airstream of a well-maintained air-handling system with no reported building-related illness were enumerated. Visually the system appeared clean, but large populations of bacteria were found on the fin surface of the supply-side cooling coils (10(5) to 10(6) CFU cm-2), in drain pan water (10(5) to 10(7) CFU ml-1), and in the sump water of the evaporative condenser (10(5) CFU ml-1). Representative bacterial colony types recovered from heterotrophic plate count cultures on R2A medium were identified to the genus level. Budding bacteria belonging to the genus Blastobacter dominated the supply surface of the coil fins, the drain pan water, and the postcoil air. These data and independent scanning electron microscopy indicated that a resident population of predominantly Blastobacter bacteria was present as a biofilm on the supply-side cooling coil fins.