Air-controlled, direct-acting relief valve - pilot capacity

Capacity: 2.5 gpm10 L/min. | Cavity: T-8A
RBAR : Air-controlled, direct-acting relief valve - pilot capacity
Technical Features [ + ]

Two-port, pilot-stage, air-controlled, direct-acting relief cartridges are normally closed pressure regulating valves. When the pressure at port 1 (inlet) is sufficient to overcome the force due to the air signal, a flow path is opened from port 1 to port 2 (tank). These cartridges are designed for pilot flow applications and utilize Sun's T-8A cavity so they can be used in conjunction with Sun's pilot-operated, main-stage valves.

  • Utilizes the Sun T-8A 2-port cavity making it the ideal choice to use in conjunction with Sun's main stage pilot or vent-to-operate cartridges. Separate pilot lines are eliminated and only one cavity needs to be machined to accommodate both the control and primary function. Note: All 2-position, 2-way pilot stage control cartridges utilize the same cavity and are physically interchangeable. Functionality is the only consideration.
  • Note: The main stage valve should first be installed to the correct torque value followed by the T-8A pilot control section into the main stage valve to its required torque value.
  • Different pilot control port options are available. See Option Selection for details.
  • Ports 1 and 2 may be pressured to 5000 psi (350 bar).
  • Hardened poppet and seat provide consistent operation, low leakage rates and superior wear characteristics.
  • Two different oil-to-air pilot ratios are available; 50:1 and 75:1. See Option Selection.
  • Maximum pilot control port pressure is 150 psi (10 bar).
  • Backpressure at port 2 increases the relief setting by a .43 multiplier.
  • 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-8A
Series P
Capacity 2.5 gpm10 L/min.
Maximum Operating Pressure 5000 psi350 bar
Maximum Valve Leakage at 110 SUS (24 cSt) 15 drops/min.1 cc/min.
Maximum Pilot Pressure 150 psi10,5 bar
Pilot Control Port See Control OptionsSee Control Options
Valve Installation Torque 20 - 25 lbf ft27 - 33 Nm
Seal kit - Cartridge Buna: 990608007
Seal kit - Cartridge EPDM: 990608014
Seal kit - Cartridge Polyurethane: 990008002
Seal kit - Cartridge Viton: 990608006
Performance Curves [ + ]
FAQs [ + ]

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.

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 [ + ]