Solenoid Valve Selection Guide

When choosing a solenoid valve, you must first understand the specific requirements of your application. Here’s a guide to help you navigate the critical criteria for selecting solenoid valves, enabling you to streamline your search using webshop filters effectively.

Huade Hydraulic is dedicated to providing professional and reliable service.

Essential Information

Keep these key guidelines in mind when selecting a solenoid valve:

• Solenoid valves are sensitive to contaminants; ensure they operate with clean liquids or air.
• Indirectly controlled solenoid valves require a pressure differential of about 0.5 bar to function correctly. They should not be used in closed circuits or low-pressure systems. Direct and semi-direct valves can operate with a pressure differential from 0 bar.
• Verify that the fluid medium and temperature align with the valve's material specifications, including the body and seal materials.
• Solenoid valves operate quickly (around 10 ms), but improper use can generate pressure transients within the system (such as water hammer).

Key Parameters

When selecting a valve, consider these vital parameters:

Principle of Operation

Different types of solenoid valves function based on varied operating principles:

• Direct operated (operating from 0 bar)
• Semi-direct operated (operating from 0 bar)
• Indirect operated (requires a pressure differential, typically a minimum of 0.5 bar)

Selecting the appropriate operating principle is crucial. Direct operated valves can function from 0 bar, using a plunger sealed with a polymer gasket to control flow. If the solenoid is energized, the valve opens. For higher flow rates, either semi-direct or indirectly operated valves are preferred, utilizing medium pressure for operation. Semi-direct valves typically have a more powerful coil, whereas indirect valves usually require a consistent pressure differential of around 0.5 bar.

To determine if an indirect valve suits your needs, check for a permanent pressure differential of at least 0.5 bar. If that isn't the case, opt for a (semi-)direct operated solenoid valve.

Circuit Function

The circuit function denotes a valve’s role in the system. Here are the two main types:

2/2-Way

2/2-way valves feature two ports (inlet and outlet) with two positions (open and closed). Most are normally closed (NC), meaning the valve is closed until powered and opens upon electrification. Normally open (NO) valves behave oppositely, remaining open until powered. Most 2/2-way valves function in a single flow direction.

3/2-Way

A 3/2-way valve, having three ports and two positions, is typically direct operated from 0 bar and suitable for smaller flow rates. For larger orifices, consider a 3-way electric ball valve. These valves may have various circuit functions: normally closed (A), normally open (B), diverting (C), and universal (D).

Pipe Diameter and Thread Type

Solenoid valves usually feature female-threaded ports, commonly British Standard Pipe Parallel (BSPP), marked by letter G (e.g., G1/4 inch). The thread size is in inches but differs from pipe diameter; see the provided standard sizes for specifics.

Orifice, Kv-value, and Flow Rate

A solenoid valve's flow resistance is influenced by the valve body's design and the orifice diameter. The orifice is the valve's closure diameter, and typically, larger piping correlates with larger orifices.

The flow resistance is expressed via the flow coefficient Kv, representing the volume of water (in m3/hour) passing through at a 1 bar pressure. A higher Kv-value results in increased flow rates under a given pressure. You can calculate the flow rate using the following formula:

Q = Flow rate [m3/hour]
Kv = Flow coefficient
dp = Differential pressure between inlet and outlet [bar]
SG = Specific Gravity (Water = 1)

Example

For a solenoid valve with a Kv of 1.25 connected to a water pipe at 2 bar with a negligible pressure drop downstream, the flow rate can be calculated, yielding approximately 29.5 l/min.

Medium (Material Compatibility)

Solenoid valves are suitable for neutral liquids and gases like oils, fuels, water, air, or steam. Material compatibility with the medium is crucial; most valves are brass-based, suitable for numerous substances. Seal materials like FKM and EPDM have distinct properties suited for specific applications.

Pressure Considerations

The system's operating pressure plays an integral role in solenoid valve selection. Exceeding the specified pressure could lead to dangerous scenarios. It's essential to understand both the maximum and minimum pressure differential for the valve's functionality.

Temperature Range

Consider the minimum and maximum temperature specifications when selecting a solenoid valve. Avoid using water valves below 0°C due to freezing risks.

Response Time

Response time is defined as the duration from solenoid activation until the pressure reaches 10% or 90% of the maximum test pressure, often varying based on valve type. Typical direct operated valves exhibit response times between 5 and 50 ms, while indirect ones range from 50 ms to beyond. Fast-closing valves can introduce pressure waves, leading to issues in the circuit; if so, consider consulting installation guides.

Voltage and Coil

The solenoid coil transforms electrical energy into mechanical motion. Solenoids are available for both DC and AC at varying voltages, influencing valve characteristics. Most solenoid valves from JP Fluid Control come with DIN connectors for efficient coil changes and moisture protection.

IP Rating

The Ingress Protection (IP) rating indicates the protection level against hazardous access and moisture ingress. Most JP Fluid Control solenoid valve coils hold an IP-65 rating, defining their resistance to dust and water ingress.

To dive deeper into the world of solenoid valves or to locate a suitable solenoid operated directional control valve, feel free to reach out for assistance!

For inquiries regarding the 4we6 directional control valve, we are here to help.