Model Definition

• DR: Pilot-operated pressure reducing valve series

• 50: Nominal size NG50 per ISO4401 standard

• E: Internal pilot oil drain structure, built-in pilot oil return passage

• 7X: Revised 7-generation internal valve body & spool design, X = continuous optimized design variant without fixed pressure rating

Technical Parameters

1. Max inlet working pressure: 315 bar

2. Adjustable outlet pressure range: 6~210 bar (selectable by fitted internal regulating spring)

3. Nominal rated flow: Max 500 L/min

4. Working medium: Mineral-based HLP hydraulic oil, permissible viscosity 2.8~380 mm²/s, fluid temperature −20℃~+80℃

5. Mounting specification: ISO 4401-10-16-07-0 (NG50 standard bottom mounting flange dimension)

6. Pilot drain layout: Internal built-in drain channel; external drain port available as optional modification

7. Standard sealing: NBR nitrile rubber; FKM fluororubber optional for high temperature or synthetic hydraulic fluid

Interface & Connection Configuration

• Main ports: P = primary pressure inlet, A = regulated secondary pressure outlet; T drain port integrated inside valve body for internal pilot oil return

• Top regulating assembly: Hand adjustment knob with lock nut and graduated scale for fixed outlet pressure setting

• Bottom flange plane: Standard NG50 flat mounting surface for direct installation on dedicated cast steel manifold block

• Built-in integrated check valve between P and A for free reverse A→P bypass flow when upstream supply pressure drops

Core Functions

1. Stabilize constant secondary outlet pressure at port A regardless of fluctuating primary inlet pressure and variable load flow demand

2. Pilot-operated spool construction delivers high regulating accuracy and stable dynamic performance under large flow swing

3. Internal drain design simplifies pipeline layout and eliminates external backpressure interference on regulation precision

4. Integrated reverse free-flow check valve speeds up cylinder retraction and equipment reset action

5. Inherent pressure limiting property protects downstream cylinders, motors and piping from accidental overpressure damage

Application Scenarios

• Large hydraulic press main branch constant-pressure control circuit

• Heavy-tonnage die-casting & large injection molding machine clamping auxiliary pressure loop

• Metallurgical rolling equipment central manifold pressure stabilizing system

• Large engineering machinery centralized hydraulic power unit branch pressure regulation

• Heavy-load ship deck machinery & large metallurgical fixture hydraulic clamping control

Usage & Maintenance Instruction

1. Entire system full depressurization is mandatory before valve disassembly and maintenance

2. Do not over-tighten the adjusting knob to avoid permanent deformation of internal regulating spring

3. Replace main circuit hydraulic filter every 2000 working hours to reduce spool blocking caused by oil contamination

4. Clean internal spool assembly with filtered clean hydraulic oil in case of continuous output pressure drift during operation