BRASS PILOT-OPERATED AND GUIDED DIAPHRAGM SOLENOID VALVES
The pilot-operated solenoid valves manufactured by OLAB, represented by the Series 18000, are on-off valves suitable for liquid and gaseous fluids whose viscosity is not greater than 37 CST (or 5°E).
These are servo-controlled diaphragm solenoid valves with BSPP threaded female inlet-outlet connections (cylindrical for gas), CW617N brass casing and cap, stainless steel magnetic parts and NBR diaphragm for water, EPDM peroxide, FKM (FPM) or other elastomers upon request.
The 18000 valves are of the 2/2-ways normally closed type (2 ways 2 positions), while the 18500 valves are 2/2-ways normally open.
Both versions are available in three models:
- with coil (18000 and 18500) - (protection degree IP00)
- without coil (18010 and 18510)
- with coil + connector (18020 and 18520) - (protection degree IP65 according to the din 40050 standard).
Despite their small weight and size (due to their peculiar profile), they are extremely robust and the fluid temperature are in compliance with gasket materials and the maximum allowable viscosity.
They are suitable for all fluids compatible with the materials which the gaskets and the internal components are made of, except for the dangerous fluids of Group 1 as according to the European Directive 97/23/EC (PED).
The range includes all sizes from 3/8” to 2” with ø11.5 to ø50 (DN) holes, while coils are all Class H for continuous use (ED 100%).
The guided diaphragm pilot operated solenoid valves of the Series 20000 by OLAB are of the guided diaphragm-type with BSPP threaded female inlet and outlet connections (cylindrical for gas), CW617N brass casing and cap, stainless steel magnetic parts and FKM (FPM) diaphragm.
BRASS PILOT-OPERATED SOLENOID VALVES
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| NORMALLY CLOSED | NORMALLY OPEN |
The electro-pilot of the pilot-operated solenoid valves is not directly responsible for opening the solenoid valve.
The solenoid valve presents three sequential chambers (see drawing below):
- inlet chamber Ci (upstream the diaphragm)
- compensating chamber Cc (downstream the diaphragm and upstream the electro-pilot)
- outlet chamber Cu (downstream the electro-pilot).
In the 2/2-way normally closed (N.C.) solenoid valve, Ci and Cc are communicating by means of a compensating hole when the coil is de-energized. Therefore, the diaphragm is in a condition of balanced pressure level and DN tightness is ensured by the retaining spring load of the same diaphragm.
When the coil is energized by acting on the electro-pilot, there is an immediate communication between Cc and Cu: the sudden increase in volume of the pressurized fluid over the diaphragm (Cc + Cu > Ci) causes, according to the Boyle-Mariotte’s law, a pressure drop.
The diaphragm is no longer in a condition of balanced pressure level (pressure under it is higher than pressure over it) and swells up in the higher pressure direction raising up and opening the DN to let the fluid flow.
In the 2/2-way normally open (N.A.) solenoid valve, Cc and Cu are communicating when the coil is de-energized and pressure under the diaphragm is higher than pressure over it and as a result, the diaphragm is raised to let the fluid flow.
When instead the coil is energized, the communicating passage between Cc and Cu is closed. The volume available to the pressurized fluid above the diaphragm is suddenly reduced and, always because of the Boyle-Mariotte’s law, this results in a pressure increase above the diaphragm. The lack of balance so produced makes the diaphragm close on the seal.
CUSTOM SOLUTIONS
OLAB does not only produce a vast range of fittings, it also supplies rapid and effective custom solutions thanks to its competent, flexible and dynamic design office. Our team of engineers collaborates actively with the main Italian and foreign companies operating in the railway and automotive industry. They propose innovative solutions designed to improve performance in terms of plant safety and efficiency. The close relationship established goes well beyond an ordinary customer-supplier relationship. It culminates in an actual “engineering partnership”, in which OLAB is involved right from the design stage. This new concept of cooperation between OLAB and its customers has led this year to the creation of the new OLAB Railway Division, where kits (shaped pipes and fittings) are pre-assembled ready for final installation by the customer. The advantages of these coded and packaged assembly kits are a significant reduction in installation times and considerable cost saving.
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