DESIGN OF A BY-PASS VALVE

AIM:

Design of a Solenoid in-line By-Pass Valve with Inlet Día of ∅9 mm and Outlet Día of ∅11 mm using Autodesk Inventor.

SOLENOID VALVE:

A solenoid valve is an electromechanically operated valve. Solenoid valves differ in the characteristics of the electric current they use, the strength of the magnetic field they generate, the mechanism they use to regulate the fluid, and the type and characteristics of fluid they control. The mechanism varies from linear action, plunger-type actuators to pivoted-armature actuators and rocker actuators. The valve can use a two-port design to regulate a flow or use a three or more port design to switch flows between ports. Multiple solenoid valves can be placed together on a manifold.

Solenoid valves are the most frequently used control elements in fluidics. Their tasks are to shut off, release, dose, distribute or mix fluids. They are found in many application areas. Solenoids offer fast and safe switching, high reliability, long service life, good medium compatibility of the materials used, low control power and compact design.

Solenoid valve designs have many variations and challenges. Common components of a solenoid valve are:

• Solenoid subassembly

1.           Retaining clip (a.k.a. coil clip)
2.           Solenoid coil (with magnetic return path)
3.           Core tube (a.k.a. armature tube, plunger tube, solenoid valve tube, sleeve, guide assembly)
4.           Plugnut (a.k.a. fixed core)
5.           Shading coil (a.k.a. shading ring)
6.           Core spring (a.k.a. counter spring)
7.           Core (a.k.a. plunger, armature)

• Core tube–bonnet seal
• Bonnet (a.k.a. cover)
• Bonnet–diaphragm–body seal
• Hanger spring
• Backup washer
• Diaphragm
  1. Bleed hole
• Disk
• Valve body
  1. Seat

The core or plunger is the magnetic component that moves when the solenoid is energized. The core is coaxial with the solenoid. The core's movement will make or break the seals that control the movement of the fluid. When the coil is not energized, springs will hold the core in its normal position.

The plugnut is also coaxial.

The core tube contains and guides the core. It also retains the plugnut and may seal the fluid. To optimize the movement of the core, the core tube needs to be nonmagnetic. If the core tube were magnetic, then it would offer a shunt path for the field lines. In some designs, the core tube is an enclosed metal shell produced by deep drawing. Such a design simplifies the sealing problems because the fluid cannot escape from the enclosure, but the design also increases the magnetic path resistance because the magnetic path must traverse the thickness of the core tube twice: once near the plugnut and once near the core. In some other designs, the core tube is not closed but rather an open tube that slips over one end of the plugnut. To retain the plugnut, the tube might be crimped to the plugnut. An O-ring seal between the tube and the plugnut will prevent the fluid from escaping.

The solenoid coil consists of many turns of copper wire that surround the core tube and induce the movement of the core. The coil is often encapsulated in epoxy. The coil also has an iron frame that provides a low magnetic path resistance.

MATERIALS:

The valve body must be compatible with the fluid; common materials are brass, stainless steel, aluminum, and plastic.

The seals must be compatible with the fluid.

To simplify the sealing issues, the plugnut, core, springs, shading ring, and other components are often exposed to the fluid, so they must be compatible as well. The requirements present some special problems. The core tube needs to be non-magnetic to pass the solenoid's field through to the plugnut and the core. The plugnut and core need a material with good magnetic properties such as iron, but iron is prone to corrosion. Stainless steels can be used because they come in both magnetic and non-magnetic varieties.For example, a solenoid valve might use 304 stainless steel for the body, 305 stainless steel for the core tube, 302 stainless steel for the springs, and 430 F stainless steel (a magnetic stainless steel) for the core and plugnut.

USES:

An installation engineer should first understand the purpose of the bypass line before installing a bypass valve onto it. A bypass piping line is laid for two reasons:

• To act as a backup line so as to allow continuous operation in case any failure or damage occurs to the main pipeline equipment
• To supplement the performance of the mainline valves

2-WAY SOLENOID VALVES

2-way solenoid valves operate in a manner analogous to single-pole single-throw (SPST) electrical switches: with only one path for a flow.

Solenoid valve symbols often appear identical to fluid power valve symbols, with “boxes” representing flow paths and directions between ports in each of the valve’s states. Like electrical switches, these valve symbols are always drawn in their “normal” (resting) state, where the return spring’s action determines the valve position.

SCHEMATIC:

COMPONENTS OF SOLENOID BY-PASS VALVE:

INLET ADAPTOR (M12x1.5-6g)

COIL COVER

SEAL

TEFLON BUSH

SPRING SPACER (1mm T)

OUTLETR ADAPTOR (M14x1.5-6g)

SPRING (P-1.7, H-10)

M4x10L HSH SCREW

PLUNGER SUB ASSEMBLY:

Exploded View

Half Section View

PLUNGER PART 1:

PLUNGER PART 2:

PLUNGER PART 3:

VALVE BODY SUB ASSEMBLY:

PART I1:

PART I2:

PART I3:

40µ FILTER ELEMENT

ASSEMBLED SOLENOID BY-PASS VALVE:

Exploded View:

Half Section View:

CONLUSION:

A Solenoid in-line By-Pass Valve was created using Autodesk Inventor with Inlet Día of ∅9 mm and Outlet Día of ∅11 mm. Threaded joints were used at both inlet and outlet to fix the fluid lines to the By-Pass valve.