Direct-acting relief valve - pilot capacity
Two-port, pilot-stage, direct-acting relief cartridges are fully adjustable, normally closed pressure regulating valves. When the pressure at port 1 (inlet) is sufficient to overcome the spring force (valve setting), a flow path is opened from port 1 to port 2 (tank).
- 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.
- 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.
- Backpressure at port 2 (outlet) is directly additive to the pressure setting at port 1 (inlet).
- 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.
- 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.
|Capacity||2.5 gpm10 L/min.|
|Factory Pressure Settings Established at||2 in³/min.30 cc/min.|
|Maximum Operating Pressure||5000 psi350 bar|
|Response Time - Typical||2 ms2 ms|
|Maximum Valve Leakage at 110 SUS (24 cSt)||15 drops/min.1 cc/min.|
|Valve Hex Size||7/8 in.22,2 mm|
|Valve Installation Torque||20 - 25 lbf ft27 - 33 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|
|Seal kit - Cartridge||Buna: 990608007|
|Seal kit - Cartridge||EPDM: 990608014|
|Seal kit - Cartridge||Polyurethane: 990008002|
|Seal kit - Cartridge||Viton: 990608006|
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.
- For Series 1 cartridges configured with an O control (panel mount handknob), a .75 in. (19 mm) diameter hole is required in the panel.
- Sun Cartridges with EPDM Seals
- Series 4 PLUS Cartridges Offer Higher Flows with Lower Pressure Losses
- 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
- Pressure Relief and Regulating Cartridge Valve Technical Tips
- Pilot Operated, Balanced Poppet Relief Valves
- Sun Expands Corrosion-Resistant Solutions
- Sun Offers Zinc-Nickel Plating for Corrosion Resistance
- Performance Data
- Sun's Floating Style Screw-In Cartridge (719.9 KB)
- Units of Measure, Settings, and Conversions
- Cavity Information (S-171) and Tooling
- Sun Model Code Explanation; 999-901-334 (343.9 KB)
- Cartridges: Materials of Construction
- Fluid Recommendations: Oil Viscosity, Cleanliness & Temperature
- Pressure Equipment Directive 2014/68/EU