Guige for correct solenoid valve specification

  This document is made with intention of choosing exact solenoid valve from our range. For this reason, guide is going to specify the main technological notions, enabling our customers to become the first collaborators in design of new products with manufacturers.

Operation principles 

  As already mentioned, a solenoid valve is combination of two main parts: one is electromagnet, made up of solenoid and it's movable core, and the second is valve body with the relative circuit connections, with one or orifices.
Solenoid coil valve is defined as such since it has the basic characteristic of a solenoid, mounted in the guide housing into which plunger operates. This can be main one or it can in turn give the command for performing the partial or total fluid intercepting.
In the solenoid, the internal space is occupied by ferromagnetic material which constitutes the core(mobile and fixed).
When coiled is energized by an electrical current, a magnetic field is generated, that will cause the movement of the mobile core, which is free to slide in the guide (made out of nonmagnetic material) toward fixed core which in turn is fixed in the same housing by way of welding or trough a finer sealing thread.
In normally-closed valve version the mobile core is kept apart from the fixed core (in closed position) by a spring that will return into the same position after the action of the magnetic field have ceased.

Types of operation 

  According to the type of operation carried out, the following categories of solenoid valves can be classified: 

Direct Action 

Closed position

  In rest position the coil is not energized by a current; with the help of fluid pressure, the core's spring pushes the sealing pad against the valve seat, thus keeping valve closed. 

Open Position 

  When solenoid valves is energized, mobile core is attracted by the fixed core, thus allowing the fluid to flow trough solenoid valve opening. Maximum pressure difference allowed is reduced with increasing of seat diameter. 

Servo-Controlled Action 

Closed position 

  In rest position, trough the equalizing opening, fluid excises a pressure on the sealing pad of the main opening (membrane).

Sealer pad remains in closed position since, at even fluid's pressure, the upper surface is greater than the lower one. 

Open position 

  When solenoid valve is energized, outlet hole is opened. A drop in fluid pressure is caused on the upper surface of the main membrane, which causes its lifting by way of the fluid pressure on the lower surface. For correct operation it is mandatory for the outlet opening to be of a diameter greater than equalizing one. Therefore this typology of valve foresees a minimum pressure value for correct operation to be guaranteed.

Servo-Assisted or mixed operation 

  These are of the same type as those servo-controlled, with the difference that the control seal element (mobile core) is close-coupled to membrane, thus already guaranteeing proper operation from 0 bar.

Normally open valves 

   There is also a possibility of having normally open version. This is obtained by inverting position mobile core in relation to fixed one (Series 61, 65, 87). Mobile core is kept open by a spring; when coil is energized, mobile core is drawn towards the seat of fixed core thus shutting off the outlet.