Vent-to-open, spring-biased closed, unbalanced poppet logic element with pilot source from port 2

Capacity: 300 gpm1100 L/min. | Cavity: T-19AU
LOKB : Vent-to-open, spring-biased closed, unbalanced poppet logic element with pilot source from port 2
Technical Features [ + ]

These unbalanced, vent-to-open logic valves are 2-way switching elements that are spring-biased closed and have port 2 as a pilot source. With port 3 blocked, the valve will remain in the closed position in the 2 to 1 direction and will function as a check valve from 1 to 2. With port 3 vented, the valve will open provided there is sufficient pressure to overcome the spring force. The force generated at port 3, plus the spring force, must be greater than the sum of the forces acting at port 1 and port 2 for the valve to remain closed. NOTE: The pilot area (port 3) is 1.8 times the area at port 1 and 2.25 times the area at port 2.

  • These valves will work in Sun's standard T-19A cavity at lower capacity. To realize the full stated capacity, the T-19AU cavity should be used.
  • These valves open quickly when vented. Time to close is difficult to predict as it is dependent on the rate of flow and the pressure drop created as it closes.
  • Because these valves are unbalanced, operation is pressure dependent. Opening and closing of the poppet are functions of the force balances on three areas: Port 1 = 100%, Port 2 = 80%, and the Pilot Area = 180%.
  • These valves are pressure responsive at all ports, therefore it is essential to consider all aspects of system operation through a complete cycle. Pressure changes at any one port may cause a valve to switch from a closed to an open position, or vice versa. All possible pressure changes in the complete circuit must be considered to assure a safe, functional system design.
  • All ports will accept 5000 psi (350 bar).
  • Corrosion resistant cartridge valves are intended for use in corrosive environments and are identified by the model code suffix /AP for external stainless steel components, or /LH for external zinc-nickel plated components. See the CONFIGURATION section for all options. For further details, please see the Materials of Construction page located under TECH RESOURCES.
  • 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.
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Technical Data [ + ]
Note: Data may vary by configuration. See CONFIGURATION section.
Cavity T-19AU
Series 4
Capacity 300 gpm1100 L/min.
Maximum Operating Pressure 5000 psi350 bar
Maximum Valve Leakage at 110 SUS (24 cSt) 10 drops/min.0,7 cc/min.
Pilot Volume Displacement .47 in³7,7 cc
Area Ratio, A3 to A1 1.8:11.8:1
Area Ratio, A3 to A2 2.25:12.25:1
Control Orifice Diameter .035 in.0,9 mm
Valve Hex Size 1 5/8 in.41,3 mm
Valve Installation Torque 350 - 375 lbf ft474 - 508 Nm
Model Weight 2.60 lb1,20 kg
Seal kit - Cartridge Buna: 990019007
Seal kit - Cartridge Polyurethane: 990019002
Seal kit - Cartridge Viton: 990019006
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Performance Curves [ + ]
Performance Curve for LOKB: Vent-to-open, spring-biased closed, unbalanced poppet logic element with pilot source from port 2 Performance Curve for LOKB: Vent-to-open, spring-biased closed, unbalanced poppet logic element with pilot source from port 2
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FAQs [ + ]
Direct acting or pilot operated - what do I use?

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.

I need to discharge a large accumulator. How can I increase the capacity of my discharge circuit?

Because of the very high ratio, the COFO has limited capacity. The discharge path is across a .050 inch (1,3 mm) diameter orifice. If you have large accumulators combined with low precharge pressures, this may not discharge the energy quickly enough. Using the COFO XDN cartridge in conjunction with an LODA XDN will provide capacity for larger applications.

How big is a drop of hydraulic oil?  

There are exactly 250 Sun drops in a cubic inch or 15 in a cc.

What parts of the Sun cartridge valve are field serviceable?
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.
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  • LOKB8Vent-to-open, spring-biased closed, unbalanced poppet logic element with pilot source from port 2 and integral T-8A control cavity
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Additional Resources [ + ]
Highlights
Technical Tips
Technical Information
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