Mechanical Registration - Variable Gravity TVC

A positive displacement meter measures gross volume regardless of temperature and/or specific gravity. On those products with 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°F [15°C]). Whether or not a Temperature Volume Compensator should be used in a meter assembly would be determinded 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 a 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 plate of the Temperature Volume Compensator.