The UNIVAC I relied on approximately 5,200 vacuum tubes for its central logic and processing.  Because thousands of tubes ran simultaneously, generating substantial heat and power (drawing roughly 125 kW for the system), burned-out tubes were a frequent point of failure requiring regular maintenance and replacement by technicians. 

The architecture utilized around 13 different types of vacuum tubes, such as the 25L6GT (an octal-based beam power tetrode). Major electronics manufacturers like RCA, General Electric, and Sylvania produced them, often branded interchangeably with UNIVAC or Remington Rand markings