Q. On what basis are fire and water tube boilers are classified?
✅ Correct Answer: (D)
depending tubular heating surface
Explanation: based on the contents of the tubular heating surface, boilers are primarily classified as fire tube boiler and water tube boiler. fire tube boilers those in which production of combustion pass through the tubes and water tube boilers are those in which the products of combustion surround the water tubes from outside.