The two numbers in a valve designation describe different parts of the function.
Read the slash designation
Festo explains that the first number identifies ports and the second identifies switching positions. Thus 3/2 and 5/2 share a position count but not a port count. Primary reference: Festo directional-valve designations.
Keep the actual symbol beside the designation. Numbers do not replace the internal path drawing or establish the actuation, electrical interface and selected operating conditions. A purchasing line should identify the function being requested before part dimensions are compared.
A hypothetical circuit-description gap
Imagine a requirement identifies two separate actuator chamber connections, but a quotation lists only a valve name without its function symbol. The reviewer should trace how supply, working paths and exhaust are represented in each switching position. A two-position description alone does not settle the chamber-path question.
Prepare rows for each position and columns for the declared connections. Keep unused or unknown paths visible. This original worksheet compares documentation; it provides no field port assignment, actuator installation method or HM circuit claim.
Complete the functional comparison
Ask the supplier to identify the exact symbol and variant applicable to the proposed circuit. Retain manual override, actuation and relevant supply details in separate fields, because they answer additional questions beyond the two-number designation.
A replacement can preserve a mounting pattern while changing function. Compare the complete relationship and approved drawing rather than accepting mechanical fit as functional equivalence. This guide helps a buyer read basic valve terminology without assuming every three-port or five-port device uses the same path assignment, controller policy or abnormal-condition response across every application.
Customer Questions
Does the first number identify switching positions?
No. It identifies ports in this notation.
Does equal position count prove equal paths?
No. Read the complete function symbol.
Can mechanical fit replace the function comparison?
No. Preserve the actual circuit relationship.
Primary References
These references support the technical principles discussed in this guide. The worked examples and review questions are educational.
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