Sun’s New Solenoid-Operated Relief Valves
By Mike Osenga16 November 2018
New to Sun Hydraulics’ cartridge portfolio and to the FLeX Series family, the company has introduced four new solenoid-operated relief valves. With a 2-stage, field-adjustable design, the new valves are designed to offer pressure regulation with up to 25 gpm (100 l/min) flow rates.
The Sun RVC valves offer fully adjustable ventable and blockable relief functions. Sun said the new valves were designed to reduce the complexity and improve the reliability and safety of hydraulic systems. To reduce complexity, Sun said the valves combine the functionality of two valves into one body and one cavity, reducing materials and creating a more compact and efficient system. The reliability improvement comes from the main stage orifice being protected by a 150-micron stainless steel screen.
To improve safety, Sun said the adjustment screw is leak-free and contains a mechanical stop to prevent the screw from backing out, offering safe, reliable field adjustment.
The RVC valves are two-stage, balanced piston relief valves. In relief mode, the valves open to tank, throttling flow to regulate the pressure when the pressure at the inlet reaches the valve setting, which is adjustable. Energizing the solenoid activates or deactivates the relief function. Four versions are available: the RVCK, a normally vented, energize to relief design; the RVCL normally in relief, energize to vent; the RVCM, normally in relief, energize to block; and the RVCN, normally blocked, energize to relief.
Sun said the RVC valves are targeted at fixed displacement pump applications, with each model in the valve family having a distinct advantage to specific hydraulic systems and applications.
• The RVCK – Use for pump start-up to unload until pressure is built, eliminating stress on the system, then energize during operation.
• RVCL – Allows the user to energize at start-up and de-energize during operations to keep power consumption lower during use.
• RVCM – For circuits that require two pressure settings, one with a high setting at acceleration, and one with a setting that is constant. The blockable RVCM regulates pressure throughout.
• RVCN – Use the relief function to preload the cylinder and avoid decompression shock in systems built for high capacities.
The new valves offer interchangeable coil options – using the 740 Series high-power and 747 Series hazardous location coils in a range of coil terminations and voltage options. The valves are available in 15 gpm (60 l/min) and 25 gpm (100 L\l/min) nominal flow rates. A variety of coil termination and voltage options are available, with and without surge protection.
The 740 Series high-power coils come in 12, 14, 24, and 28 Vdc and 115 and 230 Vac versions, and are DIN 43650 Form A (IP65/IP67 rated) and Deutsch DT04-2P (IP69) rated. Transient voltage suppression (TVS) diode is optional for dc coils and standard for ac coils.
The 747 Series hazardous location (explosion-proof) coils have ATEX, IECEx and CSA global certifications and are certified for gas and dust environments (T4 compliant for gas, T135°C for dust). Further they are CE compliant. The 30-W coils come in 12 and 24 Vdc and 115 and 230 Vac options. The DC coils have integral TVS diode and offer 48-Vdc breakdown voltage, while the AC coils are internally rectified.