Description
1" Proportional Pressure Limiting Valve 3–200 Bar – RSG 785-E
The RSG Type 785-E is an electronically controlled proportional pressure limiting valve designed for stepless overpressure control in high-pressure liquid systems using a 0–10V analogue control signal.
The valve operates on a pressure-balanced principle and is installed in a bypass circuit. This allows the process-media pressure to be several times higher than the pneumatic control pressure, with versions covering pressure ranges up to 200 Bar.
When system pressure exceeds the electrically determined set pressure, the valve progressively opens the bypass flow to limit the pressure. This makes the 785-E particularly suitable for protecting pumps, pipework, test equipment and high-pressure process systems where the required pressure limit needs to be changed automatically.
Stepless 0–10V Pressure Control
The 785-E provides continuously adjustable pressure limitation rather than simple ON/OFF control.
Control Signal: 0–10V
Electrical Supply: 24V DC
Pressure Range: Up to 200 Bar
The electrical set-point signal determines the required pressure limit, allowing the valve to be controlled directly from compatible:
✓ PLC Analogue Outputs
✓ Process Controllers
✓ Machine Control Systems
✓ Automated Test Equipment
✓ Remote Pressure Controls
✓ Variable Pressure Systems
Pressure-Balanced Bypass Design
The RSG 785-E is intended for installation as a bypass pressure limiting valve.
Rather than being installed as a conventional inline pressure reducing regulator, the valve connects between the pressure side of the system and a free return or discharge path.
The pressure-balanced construction allows the controlled media pressure to be substantially greater than the pneumatic control pressure.
When the selected pressure limit is reached, bypass flow increases to prevent the system pressure continuing to rise.
Pressure, Orifice & Flow Options
The 785-E is available in four nominal sizes and two actuator configurations.
DN10 – 10mm
Pressure: 12–160 Bar
Maximum Flow: 3.0 m³/h
Actuator: AG1
DN12 – 12mm
AG1 Pressure: 10–120 Bar
AG2 Pressure: 10–200 Bar
Maximum Flow: 6.0 m³/h
DN15 – 15mm
AG1 Pressure: 5–64 Bar
AG2 Pressure: 5–140 Bar
Maximum Flow: 8.3 m³/h
DN20 – 20mm
AG1 Pressure: 3–40 Bar
AG2 Pressure: 3–80 Bar
Maximum Flow: 14.1 m³/h
All versions use a G1 BSP connection with AG1 single-piston and AG2 double-piston actuator versions; DN10 is not available with AG2.
AG1 & AG2 Actuator Options
Two pneumatic actuator arrangements allow the 785-E to cover different pressure ranges.
AG1 – Single Piston
Used for pressures up to approximately 160 Bar depending upon nominal diameter.
AG2 – Double Piston
Provides greater actuation force for the higher-pressure configurations, including the DN12 version rated up to 200 Bar.
High Flow Capacity
Maximum flow increases substantially with nominal diameter:
DN10: 3.0 m³/h
DN12: 6.0 m³/h
DN15: 8.3 m³/h
DN20: 14.1 m³/h
This provides a choice between very high pressure capability and increased bypass flow capacity according to the system requirements.
Stainless Steel Construction
Body: AISI 303 Stainless Steel
Seal: FKM
Connection: G1 BSP
The stainless steel body provides a robust construction for demanding high-pressure industrial liquid systems.
Media compatibility should be confirmed against the AISI 303 stainless steel and FKM sealing for the actual process liquid.
Liquid Media & Filtration
Media: Compatible Liquids
Maximum Media Contamination: 50µ
The 785-E is designed to tolerate liquid contamination up to 50 microns.
Control Air Filtration: 40µ
Maximum Control Air Pressure: 8 Bar
The process liquid and pneumatic control air have different filtration requirements and should not be confused: 50µ applies to the controlled liquid; 40µ applies to the pilot/control air.
Temperature
Media Temperature: 0°C to +60°C
Ambient Temperature: 0°C to +50°C
These limits apply to the standard AISI 303 / FKM configuration.
Electrical Specification
Nominal Voltage: 24V DC
Control Signal: 0–10V
Maximum Residual Ripple: 10%
Voltage Tolerance: ±10%
Power Consumption: 2.5 Watts
Duty Cycle: 100% ED
Electrical Connection: M12x1
Protection: IP65 with Connector
Preferred Mounting: M12 Connector Upright
The manufacturer's specification confirms the 24V DC supply, 2.5W consumption, continuous-duty operation and IP65 protection.
M12 Electrical Control
The M12 connection carries both the electrical supply and analogue set-point interface.
The connection diagram on page 1 identifies:
Pin 1 – Power Supply
Pin 2 – Set Point (-)
Pin 3 – GND (-)
Pin 4 – Set Point (+), 0–10V
This allows straightforward integration with PLCs and electronic process controllers.
Installation Requirements
Correct pipework design is particularly important with a bypass pressure limiting valve.
The manufacturer specifies minimum straight flow-calming sections of:
✓ 3 × Pipe Diameter Before Valve
✓ 5 × Pipe Diameter After Valve
The outlet or T-side must discharge freely with no dynamic back pressure and with the lowest practical flow resistance.
This is important because excessive outlet restriction can affect pressure-limiting performance.
Minimum Residual Pressure
The minimum achievable residual pressure varies according to valve size and flow.
The manufacturer's graph on page 3 shows that residual pressure increases as bypass flow increases, with the larger DN20 version providing the lowest residual-pressure characteristic of the range.
This should be considered where the application requires both high bypass flow and the lowest possible pressure after the valve begins relieving.
Typical Applications
✓ Pump Overpressure Protection
✓ High-Pressure Process Lines
✓ Bypass Pressure Limiting
✓ Hydraulic Test Systems
✓ Industrial Fluid Control
✓ High-Pressure Test Rigs
✓ Automated Machinery
✓ Variable Pressure Systems
✓ Process Skids
✓ PLC Controlled Pressure
✓ Pump Circulation Systems
✓ OEM Pressure Control
Why Choose the RSG 785-E?
The RSG 785-E provides electronically adjustable overpressure protection for systems where a conventional mechanically adjusted relief valve does not provide sufficient process flexibility.
Its 0–10V proportional control input allows the pressure limit to be changed remotely or automatically, while the pressure-balanced bypass design enables media pressures substantially higher than the available pneumatic control pressure.
With pressure ranges from 3 Bar up to 200 Bar, flow capacities from 3 to 14.1 m³/h, four nominal diameters and AG1 or AG2 actuator configurations, the 785-E can be selected around both the required pressure range and bypass flow capacity.
Available Versions
DN10 – 12–160 Bar – 3.0 m³/h
DN12 AG1 – 10–120 Bar – 6.0 m³/h
DN12 AG2 – 10–200 Bar – 6.0 m³/h
DN15 AG1 – 5–64 Bar – 8.3 m³/h
DN15 AG2 – 5–140 Bar – 8.3 m³/h
DN20 AG1 – 3–40 Bar – 14.1 m³/h
DN20 AG2 – 3–80 Bar – 14.1 m³/h
Connection: G1 BSP
Body: AISI 303 Stainless Steel
Seals: FKM
Control: 0–10V
Supply: 24V DC
The manufacturer's ordering structure identifies the range as 785-E, with DN10, DN12, DN15 and DN20 options and AISI 303 construction.
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