Q1: Check valve is used for __________ flow.

ANS:B - unidirectional

A check valve, also known as a non-return valve or one-way valve, is used for unidirectional flow.

Explanation:

• Unidirectional Flow: Check valves are designed to allow fluid (liquid or gas) to flow through them in one direction only. They prevent reverse flow or backflow of the fluid. This is particularly useful in systems where it is critical to maintain flow directionality and prevent undesired backflow, which could lead to issues such as contamination, loss of efficiency, or even damage to equipment.
• Function: Check valves operate automatically. They open when the flow is in the intended direction (forward flow), allowing the fluid to pass through. When the flow tries to reverse direction (backflow), the valve closes to prevent the fluid from moving backward.
• Applications: Check valves are commonly used in various industries and systems, including plumbing, wastewater treatment, HVAC systems, manufacturing processes, and pipelines, among others.