Ohaus Ranger 7000 Compact Scale

Ohaus Ranger 7000 Compact Scale. A laboratory balance is only as good as where it stands and how it is checked.

The models differ by 3kg 0.05g, 6kg 0.1g, 15kg 0.2g, 35kg 0.5g, 3kg 0.01g, 6kg 0.02g and 3 more.

Readability is not accuracy

The figure quoted for a balance — 0.1 mg, 0.001 g — is its readability: the smallest step it will display. Accuracy is a separate and usually larger number, and it depends on the bench, the draught, the temperature and the operator far more than on the electronics.

A balance reading to 0.1 mg on a wooden bench next to a door is a balance reading noise to 0.1 mg. Put it on stone or a dedicated anti-vibration table, away from air conditioning, doors and direct sun, and let it warm up before the first weighing of the day.

Internal or external calibration

An internally calibrated balance carries its own reference mass and adjusts itself, usually on a temperature change or a timer. An externally calibrated one needs a certified weight and someone to run the routine. Internal costs more and is the right answer wherever the balance is used by many people or moved between rooms — because the calibration that never gets skipped is the one nobody has to remember.

Where it is used

• analytical and quality control laboratories
• formulation and dispensing
• education and research
• incoming material checks

Practical note

Weigh at the centre of the pan and close the draught shield before reading; both are worth more than the last digit of the specification.

Supplied in 9 models.