Model 91 High Pressure Selector Relay is designed to select the higher of two signal pressures, and to provide a continuous output pressure (or pressure range) to a controller. The ability to precisely control pressure switching and pressure monitoring functions make the Model 91 the logical choice in dead end or low flow applications such as precision control loops.
Features
Model 91 High Pressure Selector Relay Features
- Small, rugged design - suitable for installation where space is limited
- Soft seat construction assures positive shutoff
- Low selection differential allows precise control of switching function
- Fast response -well suited for control in critical loops
- Automatic switching eliminates manual monitoring of signal pressure
Specifications
Model 91 High Pressure Selector Relay Specifications
| Parameter | Specification |
|---|---|
| Maximum Signal (Supply / Output) Pressure | 200 psig (≈ 14.0 bar / 1400 kPa) |
| Minimum Switching Differential (Sensitivity) | < 0.1 psig (≈ 0.007 bar / 0.7 kPa) |
| Maximum Differential Between Input Signals | 100 psig (≈ 7.0 bar / 700 kPa) |
| Ambient Temperature Range | –40 °F to +200 °F (–40 °C to +93.3 °C) |
| Body Material | Aluminum alloy |
| Diaphragm Material | Dupont Fairprene-coated fabric |
| Trim Material | Brass |
| Connection (Port) Size / Type | 1/4″ NPT (female) standard; BSPT (tapered) option also available. |
| Operating Principle / Use Case | Automatic switching (no manual monitoring) - ideal for dead-end or low-flow applications, precise control loops and pressure-monitoring functions. |
Q & A
Model 91 High Pressure Selector Relay Q & A
+What is the purpose of the Model 91 High Pressure Selector Relay?
The Model 91 is designed to automatically select the higher of two input pressures and deliver a continuous output pressure to a controller or device.
+What applications is the Model 91 best suited for?
It is ideal for dead-end or low-flow applications, including precision control loops that require accurate pressure monitoring and switching.
+What is the maximum signal pressure the Model 91 can handle?
The relay can handle a maximum signal pressure of 200 psig (14.0 BAR, 1400 kPa).
+What is the minimum switching differential?
The Model 91 provides highly sensitive operation with a switching differential of less than 0.1 psig (0.007 BAR, 0.7 kPa).
+What is the maximum allowable differential between the two input pressures?
The unit can accommodate a maximum differential of 100 psig (7.0 BAR, 700 kPa).
Downloads
Download Rotork Fairchild Model 90 and Model 91 Low/High Pressure Selector Relay Datasheet
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