What are the two major types of sea strainers used in the Coast Guard?

• A. Simplex and Duplex
• B. Single and Double
• C. Primary and Secondary
• D. Manual and Automatic

Answer: (A)

Sea strainers protect pumps and valves from debris in seawater by filtering what’s drawn into the system. They come in two main configurations: simplex and duplex. A simplex strainer uses a single basket and is straightforward, but you typically have to shut the system down to clean or replace the basket. A duplex strainer uses two baskets and a by-pass or switching valve, so you can isolate and clean one basket while the other continues to flow, preventing downtime. This distinction matters in Coast Guard contexts because duplex units support continuous operation for critical systems, while simplex units are simpler and cheaper for less demanding service. The other options don’t reflect the standard terminology for sea strainer configurations.