Choosing the right balance can seem like a daunting task. The two biggest questions to ask yourself; what is the most you will be weighing and what is the least you’ll be weighing. From these answers, you can extrapolate what we call the capacity and readability of the balance required for your task. The capacity is the maximum weight a balance can measure. The readability is smallest division the balance can weigh. If you know you consistently weigh items that are 2000g in weight, you will need a balance that weighs 2000g or greater. Its important to consider your container weight along with sample weight when determining the required maximum capacity. With extremely small samples, be sure to check the balance’s minimum weight requirement to ensure your sample size is greater than this value.
Choosing the right location.
Proper environmental conditions for weighing are crucial for producing accurate, repeatable, and precise measurements. To obtain the most accurate weighing results, it is important to place the device in an environment that provides stable conditions. Things to consider are temperature, humidity, and location. When determining the balances workplace, it’s important to look at the ambient temperature of the lab. The optimal operating temperature for a balance is between 10-40 C (50-104 F). With temperature oscillations, drifting in the weighing results and failure to return to the zero point when a load is removed can result. The Cascade Sciences CT-series balances feature an internal temperature sensor to account for temperature fluctuations and will automatically trigger the Internal Calibration procedure to aid in the adjustment of the balance to the new environmental conditions. The relative humidity in a workplace is optimal between 50-75%. When humidity of the workplace drops below the optimal range, the occurrence of electrostatic processes increases which can cause the weighing vessel or sample to become electrostatically charged. In turn, the balances display becomes unstable and repeatability is decreased. When selecting the final location of balance its important to take in consideration the stability of the workbench. The balance should be located on a stable workbench that is not a ected by vibrations or is unlevel. With the introduction of vibrations and an uneven surface, the balance can respond with drifting values on the display and decreased repeatability. This can also occur with direct air drafts from air conditioning systems or fans.
Regular calibration ensures accurate weighing results. By not regularly calibrating the balance, issues can arise such as: product quality issues, recalls or work because of inaccurate values, and audit issues. These can all lead to unscheduled downtime and loss of productivity. When should I calibrate? There is not one right answer. It all depends on what you are weighing, how often you are weighing, your environment, and how critical your measurement is to you. Here are some ideas on when you should be calibrating your balance:
– Calibrate your balance per manufacturers requirements. We at Cascade Sciences recommend daily calibration. Your measurements are important, so why take a chance? Save time and money and order a CT-Series balance which include an internal calibration mechanism.
– Calibrate your balance before any major critical measuring project.
– After balance movement. If your balance was moved, knocked, or pushed. Maybe something was dropped in it? It should be calibrated.
– If long breaks between following measuring series occur.
– If temperature inside the balance changes more than: 1 C or 2 C for Analytical balances or 2 C for Precision series balances.
Use proper weighing technique
Set up your balance correctly. Many people think that their balance needs to be turned on and off after each use. The truth is, leaving your balance on all the time is better for your balance and the accuracy of your readings. Balances need to acclimate to their surroundings for at least an hour and preferably a day before use. Things to consider before you start weighing:
– Keep your balance running and warmed up.
– Ensure that the room and the balance doors (for analytical models) are closed to minimize drafts.
– Check the level, and if necessary, re-level the balance.
– Press the Zero button. There are two methods of weighing. Direct weighing and Indirect weighing (or weighing by difference).
– With Direct weighing, with nothing on the pan, you’ll need to first zero the balance by pressing the zero button. Place your object on the center of the pan, not on the corners/edges, and weight until the stability icon appears.
– In Indirect weighing or weighing by difference, you would first place your empty sample container on the center of the pan and press the Tare key.
– With an analytical balance, in both methods, ensure that all doors are closed before taking any measurements.
Care for your equipment
Cleaning should be done daily or as required. To clean your balance, carefully remove the balance pan, clean and replace it. Clean up any spilt liquids and brush any spilt chemicals from the weighing chamber. Clean the glass doors (inside and out), using a soft cloth. Remove dust from the exterior of the cabinet and clean up any spilt chemicals from the balance bench area.