Question 45 1AE01 - First Assistant Engineer

The Correct Answer is C ### Explanation for why Option C (Duplex) is Correct: A **Duplex filter (or strainer) unit** consists of two parallel filter elements housed in separate chambers, along with a valve system (usually a three-way or four-way valve). This design allows the flow of fluid to be switched completely from the 'dirty' or clogged element (Chamber 1) over to the 'clean' standby element (Chamber 2) without interrupting the process or the flow line. Once the flow is rerouted, the isolated element can be opened, cleaned, or replaced while the system remains fully operational and "on the line." ### Explanation for why the other options are incorrect: * **A) Canister:** A canister filter generally refers to a housing that holds a single replaceable element. While it may be a component of a filter type (like Simplex), simply identifying it as "Canister" does not imply the dual-chamber configuration needed for continuous cleaning without shutdown. * **B) Simplex:** A **Simplex filter (or strainer) unit** contains only a single filter element. To clean or replace the element, the entire unit must be taken offline, meaning the system flow must be stopped or bypassed externally, contradicting the requirement of leaving the system "on the line." * **D) Bypass:** While a bypass line (an auxiliary path for fluid flow) can be used to isolate *any* piece of equipment for maintenance, "Bypass" is a method or component of piping, not a specific type of filter/strainer unit designed inherently for continuous on-line cleaning. The Duplex unit is the specific configuration of the filtering equipment that provides the built-in capability to switch flow internally.