Pneumatic and solenoid valve part numbers look cryptic, but they all describe the same handful of properties. Once you know what to look for, you can spec a replacement from any brand — Festo, SMC, ASCO, Numatics, Bürkert and others.
1. Ports and positions (the '5/2', '3/2' code)
A valve is described by its number of ports and switching positions. The first number is ports, the second is positions:
- 3/2 = 3 ports, 2 positions — typically for single-acting cylinders or as a pilot.
- 5/2 = 5 ports, 2 positions — the workhorse for double-acting cylinders.
- 5/3 = 5 ports, 3 positions — adds a center position (closed, exhausted, or pressured).
2. Actuation and return
- Single solenoid with spring return, or double solenoid (detented).
- Direct-acting vs pilot-operated (pilot needs a minimum pressure to shift).
- Manual override present or not.
3. Port size, flow and mounting
- Port thread: 1/8, 1/4, 3/8, 1/2 — in NPT (US) or G/BSP (metric).
- Flow capacity: Cv or Qn (l/min) — must meet the cylinder's speed demand.
- Mounting: inline (ported body), manifold/sub-base, or NAMUR (bolts to a quarter-turn actuator).
4. Coil voltage (for solenoid valves)
The coil voltage must match your control system — common options are 24V DC, 110/120V AC, and 230V AC. The connector type (DIN 43650 form A/B/C, or a flying lead) matters too. Mismatched coil voltage is one of the most common ordering mistakes.
Tell us what it controls
If the valve's markings are worn, tell us the application — what it switches, the cylinder size, port thread and coil voltage — and we'll cross-reference a verified equivalent and quote it. Send the old part number or a photo to start.