What is the difference between an analytical balance and a precision balance?

An analytical balance provides readability of 0.1 mg or better, while a precision balance typically reads to 0.001 g or 0.01 g. Analytical balances include draft shields and are designed for highly sensitive measurements. Precision balances handle larger samples and are less affected by environmental conditions.

What readability do I need for my lab application?

You need a readability that is at least one-tenth of your smallest sample weight or required measurement increment. For example, measuring 100 mg samples may require 0.01 mg readability, while gram-level work may only need 0.01 g. Selecting higher readability than necessary increases cost without improving results.

Do lab balances need to be calibrated?

Yes, all lab balances require regular calibration to maintain accuracy. Calibration ensures measurements remain traceable to certified standards. Internal calibration simplifies this process by automating adjustments, while external calibration requires manual verification with certified weights. In regulated environments, calibration records must be documented and retained.

What is the difference between readability and repeatability?

Readability is the smallest increment of weight a balance will display. Repeatability is the degree of agreement between multiple measurements of the same mass, on the same balance, under the same conditions.

What is the best way to clean my balance to ensure accurate readings?

Inspect and clean before each use. A flannel cloth or soft brush works well for dusting and light cleaning. Use a non-abrasive cleaner for light spills, and a dry flannel cloth for glass parts. Set a regular maintenance schedule for deep cleaning to ensure optimal performance and instrument longevity.

Can vibration affect the accuracy of my balance?

Yes — even slight vibration from a heavy footstep can affect accuracy. Place the balance on a sturdy benchtop away from high-traffic areas such as hallways, elevators, stairways, and doors. If that placement is not possible, an anti-vibration table should be considered.

What’s Most Important When Measuring Turbidity? (Part Two)

This is part two of a two-part series.

Measuring tools for turbidity include turbidity meters, Secchi disks, and turbidity tubes.

Secchi disks have a long tradition in measuring water transparency. They are mounted on a pole and lowered into water to indicate the level at which the disk is no longer visible and the water is no longer transparent. While these disks are highly economical and efficient, they cannot deliver the accuracy of a turbidity meter.

Turbidity tubes (also referred to as transparency tubes) are sometimes preferred for use in smaller community water supplies because of their low cost and low maintenance. Designed for field use, they take samples of water, which are then drained through the tube to reveal a black and white (Secchi) disk. The remainder of the water is then measured in centimeters. Tubes are not recommended for very low turbidity levels.

Cole-Parmer® Laboratory Benchtop Turbidity Meters, EPA compliant

Turbidity meters are digital devices that may be handheld for field or lab use or they may be benchtop models primarily for lab use. They operate by reading a beam of light which is passed through the water sample. Meters require a greater financial investment than either disks or tubes, but they deliver the best accuracy and can measure even very low turbidities. Because meters run on a power source (either batteries or electricity), they do require some maintenance.

Advanced turbidity meters can offer advantages such as push-button calibration, selectable readout modes, diagnostic error messages, and signal averaging. For those seeking to simplify routine laboratory work, the consistent performance of a turbidity meter may be worth the cost. EPA- and ISO-compliant models are available for regulatory monitoring.

View our selection of turbidity meters and turbidity testing products.

What’s Most Important When Measuring Turbidity? (Part Two)

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