Meaning: Membranous structure that functions as the circulatory system in mammal embryos until the heart becomes functional. Classified under: Nouns denoting animals. Synonyms: umbilical vesicle; vesicula umbilicus; vitelline sac; yolk sac. Hypernyms (vesicula umbilicus is a kind of...): sac (a structure resembling a bag in an animal)
electric fan; blower. Hypernyms (blower is a kind of...): fan (a device for creating a current of air by movement of a surface or surfaces) Meronyms (parts of blower): electric motor (a motor that converts electricity to mechanical work) fan blade (blade of a rotating fan)
All ECMs are variable-speed motors. However, not all variable-speed motors are ECMs. ECM blowers include a control circuit that adjusts the blower speed to compensate for increased static pressure (which can occur, for example, when dust builds up on the filter).