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Fairchild pneumatic relay family for precision pressure-control applications. The portfolio includes positive/negative bias relays, high-flow bias relays, multi-stage bias relays, adjustable-ratio relays, computing relays, snap-acting relays, reversing relays and pressure-selector relays. Model 85D, for example, provides two-stage pilot operation, 14 SCFM flow capacity and 1/8, 1/4 and 3/8 in standard ports. Model-specific pressure, flow, port and function data must be matched to the exact relay model.
Adjustable Ratio Relay (M21) is designed as a purpose-built Rotork solution for instrumentation and pneumatic control. Its configuration is intended to provide dependable mechanical movement, controlled positioning and repeatable integration with the associated valve, damper, regulator, gearbox or instrumentation circuit. The product architecture is focused on predictable operation, straightforward integration and reliable performance in industrial flow-control systems.
The product-specific technical configuration is defined by the operating principle, output arrangement, power or pressure source, control method and environmental protection associated with this model or range. Key values and capabilities identified for the product are retained above so that the item can be evaluated against the required duty, interface and installation conditions without substituting specifications from another product family.
Where the selected configuration supports electrical, pneumatic, hydraulic, analogue or network control, the actuator or instrument can be integrated with the wider plant control architecture using the available control and feedback options. Depending on the product, these can include local controls, manual override, position indication, analogue signals, fieldbus or Ethernet communications, diagnostic information, pressure-control functions, relay outputs or dedicated mechanical interfaces. Exact options remain dependent on the selected product configuration.
Rotork products are engineered around the mechanical and environmental requirements of industrial flow-control equipment. Depending on the product family, the design may incorporate sealed housings, self-locking gearing, protected mechanical components, corrosion-resistant construction, hazardous-area certification, explosionproof protection, fail-safe mechanisms, high-duty modulation or low-power operation. The technical information above identifies the characteristics applicable to this product and should be used when matching the item to the installation.
Adjustable Ratio Relay (M21) is suitable for the industrial applications associated with its product function, including valve automation, process control, water and wastewater systems, energy infrastructure, oil and gas, chemical processing, power generation, HVAC, pipeline service, instrumentation and other demanding flow-control installations. Application selection should consider valve type, torque or thrust, travel, duty cycle, control signal, pressure or power supply, ambient conditions and required protection level.
Correct selection requires matching the exact product configuration to the valve or controlled device, mounting interface, operating duty and site environment. Mechanical interfaces, electrical or pneumatic connections, operating limits, available accessories and certification requirements should all be considered before installation. The product-specific technical documentation should be used to confirm dimensions, connection details, sizing and configuration before final equipment selection.
The combination of purpose-built construction, application-specific control functionality and documented technical limits makes Adjustable Ratio Relay (M21) suitable for professional flow-control installations where reliable and repeatable operation is important. Its design supports integration into engineered systems while allowing the configuration to be selected around the actual valve, process and site requirements.
| Feature | Specification |
|---|---|
| Applications | Fairchild pneumatic relay family for precision pressure-control applications |
| The portfolio includes | The portfolio includes positive/negative bias relays, high-flow bias relays, multi-stage bias relays, adjustable-ratio relays, computing relays, snap-acting relays, reversing relays and pressure-selector relays |
| Model 85D for | Model 85D, for example, provides two-stage pilot operation, 14 SCFM flow capacity and 1/8, 1/4 and 3/8 in standard ports |
| Model-specific pressure flow | Model-specific pressure, flow, port and function data must be matched to the exact relay model |
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