Fast-acting, pilot-operated, balanced piston relief valve

Capacity: 200 gpm760 L/min. | Cavity: T-18A
RPKE : Fast-acting, pilot-operated, balanced piston relief valve
Technical Features [ + ]

Fast-acting, pilot-operated, balanced piston relief cartridges are normally closed, pressure-limiting valves used to protect hydraulics components from pressure transients. Fast opening and closing is gained at the expense of smoothness. 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 have low pressure rise vs. flow and are very fast.

  • All 2-port relief cartridges (except pilot reliefs) are physically and functionally interchangeable (same flow path, same cavity for a given frame size).
  • Will accept maximum pressure at port 2; suitable for use in cross port relief circuits. If used in cross port relief circuits, consider spool leakage.
  • Main stage orifice is protected by a 150-micron stainless steel screen.
  • Not suitable for use in load holding applications due to spool leakage.
  • 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 [ + ]
Note: Data may vary by configuration. See CONFIGURATION section.
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.
Maximum Valve Leakage at 110 SUS (24 cSt) 5 in³/min.@1000 psi80 cc/min.@70 bar
Response Time - Typical 2 ms2 ms
Adjustment - No. of CW Turns from Min. to Max. setting 55
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
Seal kit - Cartridge Buna: 990018007
Seal kit - Cartridge Polyurethane: 990018002
Seal kit - Cartridge Viton: 990018006
Performance Curves [ + ]
FAQs [ + ]

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.

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.

Only external seals are serviceable.  Sun offers replacement seal kits for all cartridge models. The applicable kit part number can be found in the product page's Technical Data table or by using our Cartridge Seal Kit search function located under Accessories. Please note: Converting the external seals from one material to another does not ensure fluid compatibility with that material due to the existence of internal seals within the cartridge.
Additional Resources [ + ]