How to Choose a Solenoid Valve: 4 Stages — Ports and Positions, Direct-Acting or Pilot-Operated, Flow and Size, Coil and Mounting

First decide ports and positions (how many ports and positions, single or double solenoid, normally closed or normally open); then direct-acting or pilot-operated (a pilot-operated valve needs enough pressure difference between inlet and outlet to shift); then match flow with the flow coefficient and port size; and finally confirm coil voltage and tolerance, electrical connector, and subbase or manifold mounting. This article covers pneumatic solenoid valves for controlling air cylinders and similar devices; valves for water, oil or steam are mentioned only where sources’ general statements help comparison. Four stages:

• Stage ① Ports and positions: ports and positions, single or double solenoid, three-position center functions, normally closed or open.
• Stage ② Direct-acting or pilot-operated: the two actuation methods, minimum pressure difference, response time.
• Stage ③ Flow and size: flow coefficient, port size, speed control.
• Stage ④ Coil and mounting: voltage and tolerance, electrical connectors, subbases and manifolds.

Source details are in the notes at the end. This is a general overview; each case needs its own assessment.

Stage ①: Ports and positions — decide how the air flows

What to do:

• Ports and positions: single-acting cylinders are usually controlled by three-port valves (3/2); double-acting cylinders by four- or five-port valves (4/2 or 5/2).
• A five-port valve has a separate exhaust for each cylinder port, so speed can be adjusted separately in each direction.
• Single or double solenoid: a single-solenoid valve returns by spring when voltage is removed; a double-solenoid valve is switched back by the other coil.
• Three-position valves — check the center function: all ports blocked holds the equipment locked in position; exhaust center vents all the air; pressure center lets both motions occur at once.
• Normally closed or open: closed when de-energized is normally closed; open when de-energized is normally open.

What public sources say: an online encyclopedia page (multiple editors; changes) says two-port valves have two ports; three-port valves connect one port to either of the other two, usually supply and exhaust; open when de-energized is normally open, closed when de-energized is normally closed. A pneumatic component distributor’s catalog page (maker data, undated) says single-acting valves are also called three-port or 3/2 valves, and double-acting valves four-port or 5/2 valves; single-solenoid valves return by spring when voltage is removed, double-solenoid valves by moving voltage from the first coil to the second; and it describes the 5/3 blocked, exhaust and pressure centers as above. A pneumatic component maker’s handbook (maker data, undated) says a three-port valve has one power outlet and a four-port valve two, three-port valves usually drive single-acting cylinders and four-port valves double-acting ones, and five-port valves have separate exhausts for each cylinder port so speeds can be set separately.

How JIAHON can help:

• A site search for “solenoid valve” (October 13, 2026), excluding spare valves dedicated to placement machines and other equipment, found four product pages of general pneumatic solenoid valves and control components used below. For specifications a page does not state, please ask.
• Pneumatic solenoid valve: the page says the series covers three 5/2 models, two of which are not listed on the page (please ask); the listed model is 5/2, single solenoid with spring return. The double-solenoid model is not listed (please ask). 3/2 and 5/3 versions, center functions, and normally closed or open are not stated; please ask. The page also has a “general range” table that it says describes pneumatic solenoid valves in general rather than this model, so it is not cited here.
• Solenoid valves, air-pilot valves and regulators: five items — two solenoid valves (one a 5-port solenoid valve, one a 4/5-port single solenoid), two air-pilot valves (one a 3/2 air-operated valve, one a 4/5-port pilot valve) and one regulator. Center functions and normally closed or open are not stated; please ask.
• Solenoid valve series page: a list of model numbers in one series, without ports, positions or coil count for each; please give the model number you need and JIAHON will quote.

Stage ②: Direct-acting or pilot-operated — check pressure and response time

What to do:

• Direct-acting: the solenoid directly moves the main valve, needing relatively more power, with actuation in about 5 to 10 ms (the sources’ example); the larger the orifice, the more solenoid force needed.
• Pilot-operated: the solenoid only moves a pilot, and the fluid’s own pressure moves the main valve — less power, usable at higher pressures and larger sizes, slower, and it needs enough inlet-outlet pressure difference to shift.
• Pilot supply: internal pilots take air from inside the valve; external pilots use a separate supply. A solenoid-pilot valve may need an external supply if the air through the power section isn’t enough to shift the spool.
• Response time: from signal to completed shift; small volumes and stronger magnetic force give faster response.

What public sources say: the encyclopedia page says direct-acting valves need relatively more power and usually actuate in about 5 to 10 ms, while pilot-operated valves use the fluid’s pressure, consume less energy and are slower (about 15 to 150 ms depending on size), and cannot operate without enough pressure difference. A 2002 water treatment magazine article (drawn from an instrument maker’s technical data) says static pressure rises with orifice size, requiring more solenoid force, so internally piloted valves are used for higher pressures and larger orifices; internally piloted valves generally need a minimum pressure difference; for vacuum, confirm the vacuum is on the outlet side; and response time runs from signal to completed mechanical switching, faster with small volumes and stronger magnetic force. The pneumatic handbook (maker data, undated) describes pressure pilots (external air signal, considered more reliable) and bleed pilots (air from inside the valve, which shifts on its own if the line is cut), and recommends an external supply for solenoid pilots when air through the power section can’t shift the spool.

How JIAHON can help:

• Solenoid valves, air-pilot valves and regulators: the page says the air-pilot valves are driven by an air signal; the 3/2 air-operated valve is listed at 0 to 1.0 MPa with spring and pilot actuation, and the 4/5-port pilot valve at 0.15 to 0.7 MPa. Both solenoid valves are listed at 0.1 to 0.7 MPa. Minimum pressure difference and response time are not stated; please ask.

Stage ③: Flow and size — enough air, fast enough, for the cylinder to move fast enough

What to do:

• Check the flow coefficient (Cv): the higher the Cv, the higher the flow; at the same port size, choose the higher Cv.
• Convert Cv to actual air flow by dividing by a pressure factor (figures below).
• For system losses, the source recommends oversizing by at least 25%.
• Speed control: five-port valves have separate exhausts for individual speed adjustment; flow controls should meter exhaust air — the source lists metering inlet rather than exhaust air as a cause of erratic cylinder motion.

What public sources say: the pneumatic handbook (maker data, undated) says higher Cv means more flow; to convert to standard cubic feet per minute (SCFM), divide Cv by a pressure factor of 0.0212 at 80 psi or 0.0177 at 100 psi — for example, Cv 0.48 at 100 psi gives about 27 SCFM; oversize by “at least 25%” for system losses; five-port valves allow separate speeds; and its cylinder troubleshooting table lists metering inlet rather than exhaust air as a cause of erratic rod motion. The distributor’s catalog page (undated) says at the same port size, choose the valve with the higher flow coefficient. The water treatment article defines Cv in gallons per minute of water (40 to 86 °F) at 1 psi pressure drop — a water definition; since this article focuses on pneumatics, its figures are not used.

How JIAHON can help:

• Pneumatic solenoid valve: the listed model has G 1/8 piping ports. Flow coefficient and usable pressure range are not stated; please ask.
• Solenoid valves, air-pilot valves and regulators: the 4/5-port pilot valve has M5 ports and the regulator 3/8 ports; solenoid valve ports and flow coefficients are not stated; please ask.

Stage ④: Coil and mounting — right voltage, right connector, right base

What to do:

• Coil voltage: confirm the control supply first. Sources list common voltages of 6, 12, 24, 120 and 220 V, AC or DC; most coils tolerate ±10% of rated voltage — check the data sheet.
• Don’t use the wrong voltage: too low and the spool may not move, or move slowly and noisily with a hot coil; too high and the coil overheats and valve life shortens; a DC coil on AC, an AC coil on DC, or a 50 Hz coil on 60 Hz can all overheat.
• AC coils draw more current at pull-in and drop to a lower holding current afterwards; if the spool sticks, the coil heats quickly and may burn out — the cause may be the valve, not a faulty coil.
• Power required depends mainly on fluid pressure and orifice size.
• Electrical connectors: several types, including plugs and DIN 43650 round and square.
• Subbases and manifolds: stacking valves on a manifold shares supply and exhaust ports, reduces piping and simplifies troubleshooting; there are several subbase interface sizes.

What public sources say: an online shop’s selection article (published 2024, page modified 2026; seller data) lists common coil voltages of 6, 12, 24, 120 and 220 V AC or DC; says most coils tolerate ±10% (a 220 V AC coil usually operates between 198 and 242 V); says AC coils have a large inrush followed by a smaller holding current and burn out quickly if the plunger sticks, which points to the valve rather than the coil; and describes the effects of low voltage, high voltage, a 24 V supply on a 12 V coil, 50 Hz coils on 60 Hz, and AC/DC mix-ups. The encyclopedia page says required power depends mainly on fluid pressure and orifice size — for example, a 3/4 inch, 150 psi, 24 V AC residential sprinkler valve draws 7.2 VA inrush and 4.6 VA holding. The pneumatic handbook says stacking valves shares supply and exhaust ports with centralized control, reducing piping and simplifying troubleshooting. Another pneumatic component maker’s catalog page (maker data, undated) lists four ISO 5599-1 subbase interface sizes (1 to 4), with sizes 1, 2 and 3 mixable on one manifold, and connector types including type A, M12, plug, central plug and DIN 43650 round and square.

How JIAHON can help:

• Solenoid valves, air-pilot valves and regulators: both solenoid valves are DC 24 V; connectors and subbases are not stated; please ask.
• Pneumatic solenoid valve: the listed model’s valve body excludes the coil, which is bought separately by voltage. The page also says mounting flange dimensions differ between makers, so cross-maker replacement usually means changing the mounting plate and piping too, and bus-type manifolds are maker-specific and almost never directly interchangeable. Subbase and connector types are not stated; please ask.
• Solenoid valve series page: two models are annotated with voltages (AC110V and AC220V); the rest don’t state voltage; connectors and subbases are not stated; please ask.
• Inverters, servo drives and solenoid valves: a mixed page of nine items — four inverters, two servo drives and three pneumatic components: two solenoid valves (one a 5-port solenoid valve with no voltage stated, one a valve body at DC 24 V) and one air regulator. Coil tolerance, connectors and subbases are not stated; please ask.
• Valves for water, oil or steam: the pneumatic solenoid valve page says vacuum and chemical valves are special specifications outside general pneumatic valves, covered separately; for valves for water, oil or steam, please ask.

To match a model, please prepare six items: single- or double-acting cylinder; working pressure and flow; control supply voltage; wiring method; whether manifold mounting is needed; and the pipe size to connect. Please contact JIAHON or email [email protected].

Further reading: Solenoid valve vs. proportional valve, solenoid valve vs. relay, solenoid valve vs. pressure regulator

Air circuits on printers and placement machines: clamping pressure and maintenance

Clamping, lifting, stopper and cleaning mechanisms in SMT equipment are mostly air-cylinder driven, and solenoid valves control those cylinders. When replacing a solenoid valve or troubleshooting the air circuit, first know the pressures the machine was set to:

• Each pneumatic mechanism has its own set pressure. After replacing a solenoid valve or regulator, return to the machine’s documented settings — too loose a clamp lets parts shift, too tight may damage boards or stencils.
• Check for leaks during maintenance. Leaks in valves and tubing can slow cylinders and delay in-position signals, ending in machine alarms or slower cycle times.
• Match specifications before replacing. Ports and positions (3/2, 5/2), coil voltage, connector and subbase should match the part being replaced (see Stages ① and ④); acceptance or maintenance records usually give the machine’s air supply conditions — check them before replacing.

Notes: sources and limitations

Limitations: response times, pressure factors, voltage tolerance, oversizing and power figures are examples or rules of thumb from the sources, not selection thresholds; they vary by maker and series. Imperial units (psi, inches, SCFM, °F) are kept as given. Product figures were read from product page text on October 13, 2026; please ask about anything not stated.