The mechanical Reed-type position indicator sensor detects and is activated when the magnetic field generated by the top of the Super-Seal valve actuator aligns with the sensor. A red LED illuminates when the sensor is triggered. In addition to providing visual confirmation of the valve's state (whether it is open or closed), the Reed sensor can also be used to switch or trigger an auxiliary device.
Super-Seal valves have two position indicator sensor slots in their valve heads, one long, one short. This sensor is activated and illuminates when:
- the valve is open and the sensor is in the short slot.
- the valve is open and the sensor is positioned at the top of the long slot.
- the valve is closed and the sensor is positioned at the bottom of the long slot.
To correctly adjust the sensor, slide it into one of the sensor slots (set screw facing out). Energize the solenoid to open the valve. Slide the sensor up and down in the slot until the LED illuminates. With a small flat head jeweler's screwdriver, tighten the sensor set screw to secure it in place.
The reed sensor has two conductors, brown (+), and blue (-). It is powered by an external power supply of 5 - 120 volts, AC or DC, and has a 100mA maximum current draw (maximum contact rating is 10W). The Reed-type sensor is recommended to trigger a digital device, such as a PLC, since it has limited current capability.
The Reed-type sensor requires a series resistor on the positive conductor to limit the current through the red LED (maximum 20mA). As voltage increases, so does the value and power rating of the resistor needed. The LED can be driven with reduced current (2mA minimum), which decreases the resistor's wattage rating, albeit at reduced brightness. For example, at 120 VAC a 2.7kO, 2W resistor is needed for maximum brightness. A 1/4W, 56kO resistor may be substituted, but the LED would pull only 2mA and brightness would be diminished significantly.
The basic calculation for the correct resistor value (at 20mA) for a DC voltage source is:
R = 50 (E-2)
and for an AC voltage source (to obtain similar brightness) is:
R = 25 (E-2.7)
where R is the resistor value needed, and E is the operating voltage.
Please see the brochure for sensor technical specifications, wiring, and suggested resistor values at some common voltages. Download the User Manual for information about wiring multiple position indicator sensors, and for complete information about the Ideal Vacuum Super-Seal family of pneumatic bellows valves and available options.
