2-way, pilot-to-shift directional valve with drain to port 4 - normally open
Symbols for DRAY
The normally-open, direct-acting 2-way directional cartridge with external drain is a pilot unloading valve used to sense pressure in one circuit to switch or unload a valve in a different circuit. When pressure at port 1 exceeds the setting of the valve, the spool shifts to block port 2 from port 3.
- The pilot area (port 1) and the spring chamber drain (port 4) are positively sealed.
- There is spool leakage between the work ports (ports 2 and 3)of less than 20 drops/min (1,4 cc/min).
- The valve is designed to not modulate and is the equivalent of a hydraulic pressure switch.
- 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-21A |
| Series | 1 |
| Capacity | .5 gpm2 L/min. |
| Maximum Operating Pressure | 5000 psi350 bar |
| Maximum Valve Leakage at Reseat | 20 drops/min.20 drops/min. |
| Reseat | >85% of setting>85% of setting |
| Valve Hex Size | 7/8 in.22,2 mm |
| Valve Installation Torque | 30 - 35 lbf ft41 - 47 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 | .30 lb0,15 kg |
| Seal kit - Cartridge | Buna: 990021007 |
| Seal kit - Cartridge | Polyurethane: 990021002 |
| Seal kit - Cartridge | Viton: 990021006 |
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.
There are exactly 250 Sun drops in a cubic inch or 15 in a cc.
In many circuits the directional cartridge is set to shift at a low pressure no matter how high the pilot pressure goes. If you use a DP__ , the pilot flow increases to significant amounts. A DR__ however will only consume a small amount of flow. A DP__ is useful when you want to block or open the pilot flow to shift the valve.
DP**s and DR**s are from the reducer/reliever family and are very capable of modulating. They are not bistable.
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