Pilot-to-close check valve
Symbols for COJA
This valve is a spring biased closed, pilot-to-close check cartridge that has a 1.8:1 pilot ratio. The valve allows flow from port 1 to port 2 and blocks reverse flow. Pressure at the pilot port opposes pressure at port 1 at a ratio of 1.8:1. This valve is most often used in regeneration circuits.
- Nominal pilot ratio is 1.8:1. This means that a pressure of 1000 psi (70 bar) at the pilot port will close a valve against a pressure of 1800 psi (125 bar) at port 1. Any decay or loss of pilot pressure could allow the valve to open, even if it is a momentary decay or loss.
- Pressure at the port 2 area directly opposes pilot pressure.
- Reverse flow through the valve from port 2 to port 1 is not possible under any condition.
- With equal pressures at all ports the valve is closed.
- In the begining the CO*A's did not have a positive seal on the pilot pistons and the CO*B's did. Now the CO*A's are positively sealed and the 2 valves are mechanically identical. CO*A's are more readily available and cost less.
- 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.
- Corrosion resistant cartridge valves are intended for use in corrosive environments and are identified by the model code suffix /AP or /LH (see CONFIGURATION section). For further details, please see the Materials of Construction page under TECHNICAL 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.
| Cavity | T-19A |
| Series | 4 |
| Capacity | 160 gpm610 L/min. |
| Maximum Operating Pressure | 5000 psi350 bar |
| Pilot Ratio | 1.8:11.8:1 |
| Maximum Valve Leakage at 110 SUS (24 cSt) | 1 drops/min.0,07 cc/min. |
| 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 | EPDM: 990019014 |
| Seal kit - Cartridge | Polyurethane: 990019002 |
| Seal kit - Cartridge | Viton: 990019006 |
There are exactly 250 Sun drops in a cubic inch or 15 in a cc.
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.
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.
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