Non-adjustable direct-acting relief valve

Capacity: 50 gpm200 L/min. | Cavity: T-3A
RDFA3 : Non-adjustable direct-acting relief valve
Technical Features [ + ]

Non-adjustable direct-acting relief cartridges are normally closed, pressure-limiting valves used to protect hydraulic components from pressure transients. When the pressure at the inlet (port 1) reaches the valve setting, the valve starts to open to tank (port 2), throttling flow to limit the pressure rise. These valves are smooth and quiet, essentially zero leak, dirt tolerant, immune to silting and are very fast.

  • Customer must specfy setting. The valve will be factory set and is tamper proof.
  • Cartridges configured with EPDM seals are for use in systems with phosphate ester fluids. Exposure to petroleum based fluids, greases and lubricants will damage the seals.
  • Will accept maximum pressure at port 2; suitable for use in cross port relief circuits.
  • Valve is relatively insensitive to varying oil temperatures and oil borne contamination.
  • Select a spring range where the desired relief setting is approximately mid-range to high between the minimum and maximum pressure to ensure maximum valve repeatability.
  • Suitable for use in load holding applications.
  • Back pressure on the tank port (port 2) is directly additive to the valve setting at a 1:1 ratio.
  • All 2-port relief cartridges (except pilot reliefs) are physically and functionally interchangeable (same flow path, same cavity for a given frame size).
  • Incorporates the Sun floating style construction to minimize the possibility of internal parts binding due to excessive installation torque and/or cavity/cartridge machining variations.
Technical Data [ + ]
Note: Data may vary by configuration. See CONFIGURATION section.
Cavity T-3A
Series 2
Capacity 50 gpm200 L/min.
Factory Pressure Settings Established at 4 gpm15 L/min.
Maximum Operating Pressure 5000 psi350 bar
Response Time - Typical 2 ms2 ms
Maximum Valve Leakage at Reseat 10 drops/min.0,7 cc/min.
Reseat >90% of setting>90% of setting
Valve Hex Size 1 1/8 in.28,6 mm
Valve Installation Torque 45 - 50 lbf ft61 - 68 Nm
Model Weight .50 lb0,25 kg
Seal kit - Cartridge Buna: 990303007
Seal kit - Cartridge EPDM: 990303014
Seal kit - Cartridge Polyurethane: 990303002
Seal kit - Cartridge Viton: 990303006
Performance Curves [ + ]
FAQs [ + ]

Direct-acting valves are used to prevent over pressure, and pilot-operated valves are used to regulate pressure. If you are unsure, use a direct-acting valve. Sun's direct acting valves are very fast, dirt tolerant, stable, and robust. Sun's pilot-operated valves are moderately fast, they have a low pressure rise vs. flow curve, and they are easy to adjust.

One graphic example is on a portable grain auger for silos. When the farmer gets caught in the auger the kick-down relief trips and allows him to escape.

Pressure setting tolerances are listed in our Performance Data page. A link to this page can also be found in the Additional Resources tab of the applicable product page.

There are exactly 250 Sun drops in a cubic inch or 15 in a cc.

Maybe not. We build in a good amount of overlap in the kick-down reliefs to prevent false tripping. This means they are not as fast as our standard pilot-operated reliefs. A direct-acting relief valve set just above the kick-down relief valve would be good insurance.

Additional Resources [ + ]