Internal vs. External Scale Calibration: Which is Right for My Laboratory?

Calibration is a crucial part of laboratory balance maintenance, with two types, internal and external scale calibration, available to choose from. What’s the difference, and why does it matter? This blog will help you make your decision.

What is Internal Scale Calibration?

Internal calibration is a function on some laboratory balances that allows you to calibrate with just the tap of a button, letting the machine do all the work. This is done using weights that are built into the balance. A motorised mechanism moves the weight onto the force restoration system. The balance reorients itself so the display will always reflect the known weight. Then, it uses it as a reference in future weighing sessions.

The whole process takes just a minute or two depending on the machine and doesn’t require any human involvement besides scheduling or starting it. This can make internal calibration an excellent choice for laboratories that are extremely busy with little downtime, and those that require frequent calibration for ultra-precise tasks.  

Scaletec offers four balances with internal calibration capabilities – Adam Equipment’s Solis and Luna Analytical and Precision Balances. To make it simple, Adam added an “i” suffix to the end of models that boast internal calibration, while those with an “e” are exclusively external calibration.

What’s External Scale Calibration?

External calibration is a function available on all weighing scales and balances, even those with internal capabilities. It requires using scale calibration weights suitable for the capacity and readability of your balance, which is often outlined in your weighing scale’s manual. Calibration weights aren’t usually included with your balance, so you’ll need to purchase them separately. Scaletec offers individual weights as well as calibration weight sets for laboratories employing balances of different capacities.

The process is simple, typically just activating calibration and placing the weight on the weighing pan when prompted, but it does require a person present to perform the job. In general, you can consider external calibration more traceable and better for audits than internal calibration, as you can see and monitor the weight, rather having them locked inside, intouchable.

Pros and Cons of Internal and External Calibration

Below is a chart comparing the pros and cons of both internal and external calibration.

Both types of calibration have their advantages and disadvantages, so it’s important to make the right choice for your needs. However, since balances with internal calibration can also be calibrated externally, we recommend keeping a calibration weight available for verification or in case of audits either way.

Why is Scale Calibration So Important?

When performing feats of science in a lab, the last thing you want is to be unsure of your weighing results – which is what could happen if you leave your balance uncalibrated for too long. Heavy use should always be balanced – pun intended – with regular and even frequent calibration so that you’ll never begin to experience the drifts and jumps in results associated with an uncalibrated machine. From that point on, you won’t be sure just when your results started to lose accuracy, which puts past work in jeopardy!

Scaletec is here to help you learn how to calibrate your balance effectively. Give us a call to learn more.