Anti-Shock, pilot-operated, balanced poppet relief valve
Symbols for RPKT
Pilot-operated, anti shock relief cartridges limit maximum system pressure and also limit the rate of pressure rise. The valve opens and then ramps closed at a constant speed, independent of settings and flows. The adjust screw determines the maximum (relief) setting and the minimum (threshold) setting.
- Will accept maximum pressure at port 2; suitable for use in cross port relief circuits.
- The seals on the adjust screw are exposed to system pressure which means this valve can only be adjusted when the pressure is removed. The setting procedure is; check the setting, remove the pressure, adjust the valve, check the new setting.
- Not suitable for use in load holding applications.
- When pressure at the inlet (port 1) exceeds the threshold setting, the valve opens to tank (port 2). The pilot section moves forward at a steady rate, increasing the setting by compressing the pilot spring. Maximum setting is achieved when the pilot section reaches a mechanical stop.
- Valve provides protection for pumps and motors from pressure transients due to sudden load changes, especially variable displacement pumps, since the displacement mechanism is sometimes too slow to catch these pressure transients.
- Valve provides protection for hydrostatic drives by reducing the jerk caused by sudden reversals. The valve is suitable for cross-port applications.
- When used with a switching device, the valve can provide the ramp characteristic typically provided by proportional valves.
- Small power units can be started against an anti shock relief to provide longer pump life.
- 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.
| Cavity | T-18A |
| Series | 4 |
| Capacity | 200 gpm760 L/min. |
| Maximum Operating Pressure | 5000 psi350 bar |
| Factory Pressure Settings Established at | 4 gpm15 L/min. |
| Control Pilot Flow | 10 - 25 in³/min.0,16 - 0,41 L/min. |
| Pressure Ramp Up Time | 400 - 600 ms400 - 600 ms |
| Response Time - Typical | 2 ms2 ms |
| Adjustment - No. of CW Turns from Min. to Max. setting | 4.54.5 |
| Valve Hex Size | 1 5/8 in.41,3 mm |
| Valve Installation Torque | 350 - 375 lbf ft474 - 508 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 | 2.50 lb1,15 kg |
| U.S. Patent # | 6,039,0706,039,070 |
| Seal kit - Cartridge | Buna: 990318007 |
| Seal kit - Cartridge | Viton: 990318006 |
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.
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.
- Sun Expands Corrosion-Resistant Solutions
- Precise electro-proportional inverse relief valve
- Pilot-Operated, Balanced Poppet, Anti Shock Reliefs
- CavitySaver multi-function valves deliver single-cartridge solutions
- 'Soft' Relief Eliminates Pressure Spikes
- Tri-Grip Handknob Now Offered From Sun as a Standard Control Option
- QuickDesign with SmartConnect Offers Drag-and-Drop Schematic Tool
- Sun Introduces 'Hybrid' Valves
- CE/TÜV Certified Pressure Relief Valves
- Sun's New FLeX Series Solenoid Valves & Coils
- Pressure Relief and Regulating Cartridge Valve Technical Tips
- Pilot-Operated, Balanced Poppet Relief Valves
- Get the relief you need. Adjustable. Ventable. Blockable. FLeX-ible.
- Sun Offers Zinc-Nickel Plating for Corrosion Resistance
- Sun Cartridges with EPDM Seals
- Pressure Relief and Regulating Valves (655.91 KB)
- Manufacturing Sun Cartridge Cavities (522.27 KB)
- Fluid Recommendations: Oil Viscosity, Cleanliness & Temperature
- Units of Measure, Settings, and Conversions
- Sun's Floating Style Screw-In Cartridge (1.06 MB)
- Performance Data
- Cavity Information (S-171) and Tooling
- Sun Model Code Explanation; 999-901-334 (343.9 KB)
- Cartridges: Materials of Construction
- Pressure Equipment Directive 2014/68/EU