Being able to properly measure a CO2 tank is integral if you plan to fill it. If a CO2 tank is overfilled, it can explode. Always make sure that the scale that you use to weigh CO2 tanks is accurate and calibrated. Also, keep a chart posted near your refill station that outlines the proper weights and fill levels for each size CO2 tank.
1. Purchase a high quality digital scale that measures in ounces. Although high quality scales may be slightly expensive, it is important to purchase one that you feel is reliable.
2. Place the empty CO2 tank on the scale. Zero out the scale so that the display reads 0.0 with the CO2 tank on it. Most scales have a button that is labeled zero.
3. Fill the CO2 tank using your fill station, while it sits on the scale. The weight on the scale will slowly climb as the CO2 enters the tank. Each size tank has a limit on how much it can hold, so as soon as the tank reaches that limit, turn off the fill station. Keep a CO2 weight chart around so that you will not forget the limits of each tank.