Test the average dry matter and specific gravity of a bulk sample
The Zeal Manual Hydrometer is a traditional industry tool for fast intake sampling and measurement of potato dry matter and specific gravity (density). It is used extensively throughout the potato world by producers of crisps, french fries, potato wedges and canned, frozen and powdered potato products.
Which manual hydrometer model should you buy?
The Zeal Manual Hydrometer is made with 3 different scales to allow for different ranges of dry matter being measured for different varieties of potato. Dry matter is not constant for a variety – it can change between years according to growing conditions and irrigation. Hence, it is not always possible to predict in advance the range of dry matter that will need to be measured.
The standard range of 17-25% (Model: POT/HYDROMETER) covers most situations. The other models (POT/HYDROMETERD4501 and 4502) tend to be used with specialist varieties.
How to use the Zeal Manual Hydrometer
An exact weight of potatoes (3.63Kg/8lbs) is placed in the basket. The hydrometer and basket are suspended in a large container of clean water at approximately 15°C/60°F. The hydrometer with basket attached must float freely. The buoyancy of the unit in water (with potatoes in the basket) determines the water level against the vertical scale in the stem which gives the readings of dry matter and specific gravity.
The point at which the water surface crosses the vertical scale is the dry matter (right) and specific gravity (left) reading.
The Zeal hydrometer is supplied with a calibration weight that lets the user check if it is floating at the Zero point on the scale in the stem before the potatoes are added to the basket. If it is not at Zero, the screw at the top of the tube can be turned slightly to raise or lower the scale inside the tube until the hydrometer floats at exactly Zero.
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