Moisture:

    • Moisture can affect the amplifiers and timing circuits
    • Cause changes in circuit impedance 
    • It is important to protect the circuitry and may be done using epoxy (most banner products are epoxy-encapsulated)
    • Condensation can affect even perfectly sealed sensors.
    • You can solve this issue by changing your choice of sensor or you sensor location.
      • NEMA 6 ratings have the best moisture seals and are able to resist occasional or prolonged submersion
      • NEMA 4 and 6 can with stand low pressure wash down
      • Fog and liquid on a lens can send the beam in the wrong direction
      • Opposed and retroreflective sensors are the most reliable
      • Diffuse divergent and convergent mode sensors are not recommend to use where moisture is a factor are 

View Next Article Sensor Temperature Considerations 

Temperature:

  • Most photoelectric sensors can be exposed to -20° to +55° Centigrade (-4° Fahrenheit to 131° Fahrenheit)
  • Extreme cold-below -40° C (-40°F) and above +100° (+212° F) you may want to use glass Fiber Optics
  • Remote sensors have higher operating temperatures but they contain only optical elements usually rated for -40° C (-40° F) and above +100° C (+212° F)

View Next Article Hazardous Environment 

Hazardous Environments:Preventing Sources of Ignition

  • Fiber optics- great way to avoiding sources of ignition
    • Plastic is the better choice because glass fiber optics are hard to seal off between the hazardous and safe environment
  • Explosion-proof enclosures
    • Can withstand pressure during an internal explosion 
    • Disadvantages to using explosion-proof enclosures
      • It is costly
      • Limited sensor choice(the ones that fit in the box)
      • Special treated wires have to be used
  • Intrinsically-Safe and NAMUR Advantages( Intrinsically-Safe- Sensors that use a low level of energy so that the amount of electrical energy is limited)
    • Reduce cost of hardware and installation
    • Easy sensor installation and alignment
    • Suitability for all classes, groups, and divisions of hazardous locations
    • Helps prevent explosions not just contain them
    • No shock hazards exist because the low voltage and current
    • Recognized internationally

View Next Article Shock and Vibrating Mounting 

Click here  to see a corrosive agents chart for picking out the proper sensor housing.

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