Variable Gravity Temperature Volume Compensators

A positive displacement meter measures gross volume regardless of temperature and/or specific gravity. On those products with a linear coefficient of expansion, a Temperature Volume Compensator automatically corrects registration to indicate the volume of the liquid at a selected base temperature (normally 60 degrees F). Whether or not a Temperature Volume Compensator should be used in a meter assembly would be determined by one or more of the following considerations: 1. The magnitude of the coefficient of expansion of a product; 2. The magnitude of variation in product temperature; 3. The commercial value of the product; 4. the degree of metering accuracy desired; 5. the requirement that the product be measured by weight instead of volume.

The Temperature Volume Compensator contains an infinitely variable transmission, which reacts to product and ambient temperature sensed by a fluid filled capillary system connected to motor bellows. Changes in product temperature produce changes in the bellows length. This change in length is sensed and mechanically transmitted to a differential. The degree to which this variation in length affects the registration is based on the coefficient of expansion, which may be set in the field on a TVC/VG (Variable Gravity) model on a scale conveniently located on the front face plate of the Temperature Volume Compensator.