Direct-acting relief valve, CE marked

Capacity: 20.8 gpm79 L/min. | Cavity: T-3A
RDFT : Direct-acting relief valve, CE marked
Technical Features [ + ]

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.

The CE marked valve is a safety valve that meets the requirements of the European Directive for Pressurized Devices (PED) 97/23/EC. The valve setting represents the excess operating pressure at which the valve opens. Valve capacity can be determined from the performance curve. It shows an approved flow which depends on the excess operating pressure. As a requirement of the PED, the system pressure at the maximum approved flow is a maximum of 10% above the excess operating pressure.

  • Standard settings for preset valves include:
    • B adjustment range: 100 bar
    • A adjustment range: 140 bar, 160 bar
    • C adjustment range: 210 bar, 250 bar and 330 bar
    Other settings are available upon request.
  • At this time RDDT and RDFT are the only Sun relief valves that are CE marked.
  • Each delivery contains a TÜV-Approval, which is a certification of the excess operating pressure and the approved flow, an EC Declaration of conformity and an instructional manual.
  • Pressure settings from 60 bar up to 420 bar are approved and certified by TÜV
  • 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.
  • 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.
  • 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 [ + ]
Cavity T-3A
Series 2
Capacity 20.8 gpm79 L/min.
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
Adjustment - Number of Clockwise Turns to Increase Setting 55
Valve Hex Size 1 1/8 in.28,6 mm
Valve Installation Torque 45 - 50 lbf ft61 - 68 Nm
Adjustment Screw Internal Hex Size 5/32 in.4 mm
Locknut Hex Size 9/16 in.15 mm
Locknut Torque 80 - 90 lbf in.9 - 10 Nm
Model Weight .50 lb0,25 kg
Seal kit - Cartridge Buna: 990303007
Seal kit - Cartridge Polyurethane: 990303002
Seal kit - Cartridge Viton: 990303006
Performance Curves [ + ]
FAQs [ + ]

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.

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.

Additional Resources [ + ]