Rancang Bangun Neraca Analitik untuk Kalibrasi Gelas Ukur Penakar Hujan Tipe Observatorium dengan Kontrol Massa

Abstract

The observatory type rain gauge is a manual type rain gauge that requires a measuring cup to measure rainfall in millimeters (mm) of rain. Precise measurement requires calibration of the measuring cup so that the scale reading on the measuring cup can be trusted. Calibration of measuring cups uses the gravimetric method by finding the volume of water by measuring the mass of water with analytical scales. Mass and volume are interrelated, where mass is volume times water density, and the scale (mm) on the glass can be converted into volume (ml) with a cross-sectional area of the observatory rain gauge is 100 cm2. Technological developments can make manual analytical balance calibration automatic by utilizing microcontrollers and pumps in filling the volume so as to reduce parallax errors when setting the meniscus or filling the volume of water in the glass. The analytical balance design obtained calibration results where the average correction value for the 50 ml set point is 0.00 ml, the 100 ml set point is -0.76 ml, the 150 ml set point is -0.02 mm, the 200 ml set point is -0.74 ml, and the 250 ml set point is 0.63 ml. The correction value obtained is still below ± 1 ml which means that the rain gauge scale is in good condition.