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The use of air purifier to clean the room with poor ventilation is considered as a fast and common solution to minimize the spread of SARS-CoV-2 nowadays. However, the efficacy of the filter within the air purifier must be tested priorly to ensure the cleanliness of the air, since the size of this novel virus is very small. Inexpensive particulate counter which is common in the market, such as HT-9600 particle counter can be used to test the efficacy of the filter if the device is properly calibrated. This paper aims to calibrate the HTI portable particulate counter to Solair3100 which has been calibrated by NIST using ISO 21501-4 and ISO 17025 standards. Both devices were used to measure the amount of particle in various places to see their characteristic. The same nonlinear trend produced by both devices in reading the amount of particle in different places made the calibration effort can be done. Data used for calibration were the average reading of the number of particles from various conditions. Calibration curve of HT-9600 particle counter was obtained by plotting the average readings of both devices in a single plot. The obtained calibration curve is a non-linear plot which represents the characteristic of particle counter in reading the amount of particle based on its respective size. The obtained calibration function from the curve shows great tendency in reading the right amount of particle in the air with minimum error. [ABSTRACT FROM AUTHOR]

One of the causes of drought crises in Indonesia was the mixing of water in the residents' dug wells with seawater — brackish water — whose salinity is high and not following drinking water standards. The lack of clean water usually occurs during the long-dry season, is advantageous because of the abundant source of solar radiation. Therefore, the brackish water desalination process can be done utilizing solar energy. Carocell 3000 solar-still has been widely used to produce purified water because of its low price and ease of use. According to the manufacturer, this solar-still can provide purified water from 65% of the solar energy it receives. Nevertheless, the information on the optimum input flow rate is missing. This study aims to determine the optimum input flowrate of Carocell 3000 solar-still to produce the maximum volume of purified water. The experiment was conducted in July by varying the amount of input flowrate ranging from 48, 72, 92, to 120 ml/min then measuring the volume of purified water produced within an hour. The limitation of only one solar-still available made the testing of parameter variations cannot be done simultaneously at the same time on the same weather conditions, so data for the analysis were collected from several days of testing. Data with the almost equal value of solar radiation were selected to see the performance of solar-still in producing the maximum volume of purified water with different variations of input flow rate. The result showed that input flowrate affects the production of purified water, but not linearly. With the average solar radiation of 461±24 W/m2, the input flow rate of 48 ml/min was the optimum input flow rate for Carocell 3000, which has an evaporator surface area of 3m2, because of its higher efficiency of purified water produced within an hour, around 34%. [ABSTRACT FROM AUTHOR]