What Is a Fill Height Tester? A Guide to Measuring Fill Level and Container Capacity
A fill height tester measures how much liquid a container holds at a given fill level, and the fill level that corresponds to a given volume. Bottle makers use it to check the capacity of their containers, and fillers use it to make sure that the declared volume is reached at the fill height set on the line. Fill height, brimful capacity and fill volume are basic data for every new bottle and for production checks.
How does a fill height tester work?
The reference method is gravimetric: the container is filled with water and weighed, and the weight of the water is converted into a volume using the density of water at its temperature. For glass containers, this method is described in ISO 8106.
On the AT2E FHT-1, the measuring sequence is automatic. The tester positions itself according to the bottle height and fills the bottle with water, while a high-precision level detection system follows the liquid level and adjusts the filling rate. A precision balance then weighs the water, and the tester calculates the volume with an automatic correction for the density and temperature of the water.
Manual methods use simpler tools: a fill height gauge measures the distance from the top of the finish to the liquid level, and a fill height syringe adjusts the water level in a bottle to a predetermined fill height.
Main applications
Bottle design: checking the brimful capacity and the fill point of a new bottle.
Container production: checking the capacity of glass and PET containers during production.
Filling lines: setting and checking the fill height that gives the declared volume.
Filled products: weighing capped bottles, then the same bottles once emptied, to find the weight of their contents.
Key concepts: brimful capacity, fill height and fill volume
Brimful capacity: the volume of the container filled to the very top of the finish.
Fill height: the distance from the top of the finish down to the liquid level. The space above the liquid is the headspace.
Fill volume: the volume of liquid in the container when it is filled to a given fill height. The FHT-1 offers three modes: brimful volume, fill height for a given fill volume, and fill volume for a given fill height, the last two with or without the brimful measurement.
Density and temperature: one gram of water is not exactly one milliliter. At 20 °C (68 °F), water has a density of about 0.998 g/ml, and it changes with temperature, which is why the weight is corrected for the temperature of the water.
Resolution: the FHT-1 measures from 0 to 3000 ml (101 US fl oz) with a volume resolution of 0.01 ml and a height resolution of 0.1 mm, and it is designed to meet the requirements of ISO 8106.
Why weighing beats reading a line
In a kitchen, a measuring cup is quick, but bakers who want the same result every time weigh their flour. The cup depends on how it is filled and how the line is read; the scale does not.
Container capacity works the same way. Reading a level on a graduated cylinder depends on the meniscus and on the eye of the operator. Weighing the water and correcting for its temperature gives a result that depends much less on who made the measurement.
Calibration of a fill height tester
A fill height tester combines a balance, a height measurement and a temperature probe, and each one is checked:
Check the balance with certified reference weights.
Check the height measurement against a reference of known height, and the temperature probe against a reference thermometer.
Measure a reference container of known capacity, record the deviations, and adjust if they exceed the acceptable limit.
A calibration pack is available as an option for the FHT-1. Clean water and containers free of air bubbles are also part of the method, since trapped air takes the place of water and lowers the result.
AT2E fill height and volume testers
AT2E covers fill height and volume from a hand gauge to an automatic tester:
FHT-1: automatic fill height tester for brimful volume, fill height and fill volume, 0 to 3000 ml, for containers 55 to 203 mm in diameter and 150 to 440 mm high; the FHTT-1 version integrates a top load tester.
FHG / FHG-D: fill height gauge for all bottle sizes, 0 to 150 mm, graduated in millimeters or inches.
FHS: fill height syringe that adjusts the water level in a bottle to a predetermined fill height, maximum suction volume 65 ml.
BWCS-A: bottle weight control system for crown capped products, which weighs the filled bottle and then the same bottle once emptied, 0 to 4000 g with a resolution of 0.01 g.
Precision scale: precision weighing scale for fill weight control.
Conclusion
Volume is what the consumer buys, and fill height is how the line delivers it. Measuring capacity by weight, with a temperature correction and a calibrated balance, gives bottle makers and fillers a common and objective reference.
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AT2E is an ISO 9001 certified company (AFNOR Certification).
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