Take your pH and ORP measurements outdoors
Our Thermo Scientific Orion portable meters are built rugged and waterproof for dependable performance, anywhere and anytime. Take advantage of one-hand operation and easy portability for any remote application without sacrificing accuracy and the reliability of your measurements. Identify the best match based on your required features, performance specifications, and budget.
Which portable pH and ORP meter is right for you?
Premium | Advanced | Basic | |
|---|---|---|---|
| Orion Star A321 pH Portable Meter (Star A3210 series) | Orion Star A221 pH Portable Meter (Star A2210 series) | Orion Star A121 pH Portable Meter (Star A1210 series) | |
 |  |  | |
| Premium rugged, easy-to-use portable field meters | Advanced portable meters, easy-to-use, dependable field meters | Basic portable meters, budget-friendly, simplified field meters | |
| Ideal for applications in: | pH, mV, ORP, and temperature testing, and field applications | Advanced pH analysis ideal for outdoor environments and field applications | IP67-rated housing for rugged protection in outdoor environments |
| pH range | –2.000 to 20.000 pH | –2.000 to 20.000 pH | 2.00 to 16.00 pH |
| pH resolution | 0.1. 0.01, 0.001 pH | 0.1. 0.01, 0.001 pH | 0.1. 0.01 pH |
| pH relative accuracy | ±0.002 pH | ±0.002 pH | ±0.01 pH |
| pH calibration points | Up to 5 | Up to 5 | Up to 3 |
| pH calibration editing | Yes | No | No |
| Range (mV) | ±2000.0 mV | ±2000.0 mV | ±1600.0 mV |
| Resolution (mV) | 0.1 mV | 0.1 mV | 0.1 mV |
| Relative accuracy | ±0.2 mV or ±0.05% of reading, whichever is greater | ±0.2 mV or ±0.05% of reading, whichever is greater | ±0.2 mV or ±0.05% of reading, whichever is greater |
| ORP mode | Yes | Yes | No |
| Range (temperature) | –5.0° to 105.0°C, 22.0° to 221.0°F | –5.0° to 105.0°C, 22.0° to 221.0°F | –5.0° to 105.0°C, 22.0° to 221.0°F |
| Resolution (temperature) | 0.1°C, 0.1°F | 0.1°C, 0.1°F | 0.1°C, 0.1°F |
| Accuracy (temperature) | ±0.1°C | ±0.1°C | ±0.1°C |
| Temperature compensation | Automatic or manual | Automatic or manual | Automatic or manual |
| Offset calibration | 1 point | 1 point | Yes |
| Data points | 5000 with date and time stamp | 1000 with date and time stamp | 50 |
| Log function | Manual, automatic with AUTO-READ or timed | Manual, automatic with AUTO-READ | Manual, automatic with AUTO-READ |
| Inputs pH electrode | BNC, reference pin | BNC, reference pin | BNC |
| Inputs ATC probe | 8 pin mini DIN | 8 pin mini DIN | 8 pin mini DIN |
| Outputs | RS232, USB | RS232, USB | --- |
| Power supply | 4 AA batteries: 800 hrs. battery life (included) or optional universal, 100–240 VAC (sold separately) | 4 AA batteries: 800 hrs. battery life (included) or optional universal, 100–240 VAC (sold separately) | 4 AA batteries: 2,000 hrs. battery life (included) or optional universal, 100–240 VAC (sold separately) |
| Enhance your productivity with accessories for your benchtop and portable meters. Meter Accessories › | |||
Take your measurements indoors with our complete lab offerings
Benchtop
pH Meters
 |
Equip your lab with our benchtop pH and ORP (Oxidation-Reduction Potential) meters that provide dependable performance, accuracy, and reproducibility for your application or analysis needs.
pH Electrodes
and Probes
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Our extensive assortment of quality pH electrodes, sensors, and probes are available in a variety of body materials, body styles, and sample requirements.
Buffers and
Solutions
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We offer a variety of NIST traceable pH buffer solutions, pH electrode storage solutions, electrode cleaning solutions, lab buffer kits, and electrode filling solutions for every application.
Orion solutions, standards and buffers portfolio
Using high-quality solutions to calibrate and maintain your sensors is the best way to ensure your data is both accurate and reproducible. Learn more about why high-quality solutions deliver correct measurements every time.
Knowledge Base: Certificates of Analysis and SDS for Orion, ROSS, AQUAfast, AquaMate, and AquaSensors products.
Orion Meters Software and Upgrades
Thermo Scientific Orion benchtop and portable meters are designed to help deliver accurate, consistent results, day after day. Boost productivity by upgrading your software today.
