Description
The OMEGA OS551A-MA-6 is a high-performance infrared (IR) thermometer designed for non-contact temperature measurement in industrial process environments. This specific model features a 4 to 20 mA analog output and a laser sighting system, optimized for integration into PLC or DCS control loops where mechanical contact with the target is impossible or hazardous.
Commercial Availability & Lifecycle Status
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Condition: New Original
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Availability: In Stock / Available via distribution
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Standard Lead Time: Ships within 2–4 business days
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Warranty: 1-Year Manufacturer Warranty
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Pricing Note: Prices for the OS550 series vary based on optic ratios and laser configurations. Contact us for a formal quote tailored to your current project.
Technical Specifications
| Parameter | Value |
| Manufacturer | OMEGA Engineering |
| Model Number | OS551A-MA-6 |
| Temperature Range | −23 to 538°C (−10 to 1000°F) |
| Output Signal | 4 to 20 mA (Linearized) |
| Optical Resolution | 30:1 (Distance to Spot Ratio) |
| Sighting | Integrated Laser Sighting (Class II) |
| Accuracy | ±1% of reading or 1.7°C (3°F), whichever is greater |
| Repeatability | ±1% of reading |
| Emissivity | Fixed at 0.95 (Industrial standard) |
| Spectral Response | 8 to 14 microns |
| Power Requirement | 12 to 36 V DC |
| Housing Material | NEMA 4 (IP65) Anodized Aluminum |
Technical Implementation & Field Considerations
Distance to Spot Ratio (30:1)
The 30:1 optical resolution is a critical factor for installation. This means that at a distance of 30 inches, the sensor measures the average temperature of a 1-inch diameter circle. If the target does not completely fill this “spot,” the sensor will average the target temperature with the background temperature, leading to significant measurement errors.
Emissivity Constraints
The OS551A-MA-6 features a fixed emissivity of 0.95. This is ideal for measuring “non-gray” bodies such as:
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Paper, wood, and rubber.
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Painted surfaces and plastic.
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Oxidized or rusted metals.
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Food products.
Note: It is NOT suitable for measuring shiny, polished, or reflective metals (like stainless steel or aluminum) without applying a high-emissivity coating (such as black paint or thermal tape) to the target surface.
Laser Alignment
The “-6” suffix denotes the laser sighting configuration. This provides a visual reference for the center of the measurement area. In field deployments, ensure the laser lens is cleaned regularly with a soft cloth and non-abrasive cleaner, as dust buildup on the lens can scatter the laser and eventually cloud the IR detector optics.
Signal Loop Wiring
The 4 to 20 mA output is a 2-wire, loop-powered configuration. When integrating with a PLC (such as an Allen-Bradley ControlLogix or Siemens S7-1500), ensure the analog input card is configured for “Sourcing” power or provide an external 24 V DC power supply in series with the loop.
Frequently Asked Questions
Can this sensor operate in ambient temperatures above 50°C?
The internal electronics are rated for operation up to 50°C (122°F). If your installation site exceeds this—common in furnace or glass-working applications—you must utilize an optional Water Cooling Jacket or Air Purge Collar to protect the sensor from thermal damage.
How do I scale the 4 to 20 mA signal in my PLC?
The output is linear across the full range of the device.
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4 mA = −23°C (−10°F)
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20 mA = 538°C (1000°F)
Use the standard linear scaling formula: $Value = \frac{(I – 4)}{16} \times (Max – Min) + Min$.
What happens if the lens gets dirty?
The sensor will “see” the temperature of the dirt on the lens rather than the target. Because the OS551A is a NEMA 4 rated device, it is resistant to moisture, but the optics must remain clear. We recommend an air purge collar for environments with high particulate matter to maintain a positive pressure of clean air across the lens.
Do you need the specific pinout diagram for the M12 connector, or are you looking for the compatible mounting bracket part numbers for this 30:1 optic model?
