Isolate aggressive, chalky or dirty media from valve parts
The armature systems in solenoid valves are made from a magnetic material that enables the valve to open and close easily. But magnetic materials are softer and less durable than non-magnetic stainless steel – and over time this means that armature systems can be damaged by aggressive, dirty or chalky media. Aggressive media cause rapid corrosion of the armature, and the impurities in dirty or chalky media can block the opening and closing movement.
The only way to overcome these problems is to separate the medium from the armature system – and this means using an isolating diaphragm. The isolating diaphragm has to follow the opening and closing of the valve, and so is typically made of rubber. But this creates another problem – due to the large surface area of the diaphragm, an increase in medium pressure can cause the diaphragm to open.
Danfoss has the solution to both these problems. By using an isolating diaphragm made from EPDM or FKM rubber – able to cope with up to 16 bar pressure – and filling the cavity of the armature system with a neutral medium, the system becomes pressure insensitive.
It works like this: as pressure increases on the diaphragm from the medium, so does the counter pressure from the isolated neutral medium, ensuring pressure remains equal on both sides.
This process means your valves function optimally – and has already been proven in a number of applications. For example, Danfoss’ isolating diaphragms helped improve the irrigation system of an English golf course. Mounting an isolating diaphragm on EV220B valves stopped dirt particles being sucked into the armature system, eliminating blockages.
A similar system also solved a corrosion problem in the armature system of EV220B valves on a Polish ship which used seawater as a medium.
Danfoss’ isolating diaphragms can be ordered separately for valve types EV210B and EV220B, or can be delivered as an integrated part of valve types EV212B and EV222B.
By Karsten Holtebo, Application Manager, Marine