Milwaukee MW151 MAX pH/ORP/Temp Logging Bench Meter

The Milwaukee MW151 MAX 3-in-1 pH/OPR/Temp. Logging Portable Bench Meter is fast, reliable, simple to operate, and is designed with a small lab space footprint.  It is ideal for use by brewers, wine makers, growers, labs, food processing, water treatment and many other applications with challenging pH measurement needs.

With up to 5-point calibration and 7 standard buffer choices (plus 2 custom buffers), the meter can be quickly calibrated to a higher accuracy compared with 1 or 2-point calibration.  The MW151 MAX is accurate to ± 0.002 pH, 8 x more accurate than some alternative meters.

The meter comes with a refillable, glass, double junction pH electrode and MA831R temperature sensor allowing the meter to automatically adjust the pH reading for the effect of temperature (ATC).

Features:

• Fast, easy-to-read results with large duel level digital LCD readout
• Extreme accuracy to ±0.002 pH | +/- 1 mV OPR | +/- 0.4°C (+/-0.8°F)
• Extended pH range (-2.00 pH to 20.00 pH / -2.000 to 20.000 pH)
• Lightweight, sleek design with small benchtop footprint
• Simple, easy-to-use logging and USB download functions, manual or on stability up to 1,000 logs
• Electrode diagnostics feature checks and displays the condition of the pH electrode. 
• Easy measurement: just place the electrode and temperature probe in the sample, gently stir and wait for the reading to stabilize
• Simple push button, automatic up to 5-point calibration for increased accuracy
• Up to 7 Standard calibration solutions (1.68, 4.01, 6.86,7.01, 9.18, 10.01 and 12.45) and 2 custom choices
• Refillable, glass, double junction lab grade pH electrode for low maintenance and high performance with a screw on cap to ensure proper storage
• Built-in rechargeable battery with 8 hours battery life (battery included)
• Selectable Auto-off feature
• Alphanumeric LCD display messages for friendly, intuitive information, warnings and error messages
• Internal clock date to keep track of different time-dependent functions (calibration, timestamp, calibration time out)
• 3-foot probe cables for extra flexibility when testing

Specifications:

• pH Range: -2.00 to 20.00 pH / -2.000 to 20.000 pH
• ORP Range: ±2000.0 mV
• Range: -20.0 to 120.00°C (-4.0 to 248.0°F)
• Resolution: 0.01 pH / .001 pH
• Resolution: 0.1mV
• Resolution: 0.1°C / 0.1°F)
• Accuracy: ±0.01 pH / ±0.002 pH @ 25°C / 77°F
• Accuracy: ±1mV
• Accuracy: ±0.4°C |±0.8°F
• pH Calibration: up to 5-point automatic pH calibration | 7 standard buffers (pH 1.68, 4.01, 6.86, 7.01, 9.18, 10.01, 12.45) and two custom buffers
• Temperature Compensation: Automatic, -20.0 to 120.0°C (-4.0 to 248.0°F) or manual
• pH electrode: MA917B/1 glass, double junction pH electrode (supplied)
• Temperature probe: MA831R (included)
• Logging: Maximum 1,000 samples (stored in up to 100 lots) / on demand, 200 samples on stability, 200 samples/ Interval logging, 1000 logs
• PC Connectivity: 1 USB Port, 1 micro USB port
• Power supply: 12VDC, 5 VDC USB Adapter (included)
• Battery life: Approx. 8 hours of use
• Auto-off: Selectable 5, 10, 30, 60 min. or off
• Environment: 0 to 50°C / 32 to 122°F; max RH 95%
• Dimensions: 230 x 160 x 95 mm (9.0 x 6.3 x 3.7 inches)
• Weight: 0.9 kg / 2.0 lbs.
• Warranty: 3 years Meter

Milwaukee MW151 Manual

CARE AND USE

pH meters usually start performing poorly because of problems with the probe, specifically the glass sensing bulb and the reference junction.  The glass bulb loses sensitivity with use and will eventually fail, which is true of all pH probes.  The reference junction is a small hole that allows the meter to compare the sample to a reference.  If the junction hole gets clogged, the pH probe will no longer function.

The life of your pH electrode can be extended in the following ways:

Storage - The pH probe needs to be kept hydrated. Long periods of dry storage will damage the sensitivity of the probe. Allowing the probe to dry out may also result in the junction hole getting clogged.  Storing in pH probe storage solution or pH calibration buffers will help address both these issues. Do not store in tap water and DI water, this will damage the sensitivity of the probe.  The best way to store the probe is with the probe's cap filled with storage solution or calibration buffer and the cap tightened to prevent leakage. It is also recommended to store the electrode upright to further reduce the potential for leakage.

Cleaning and Maintenance - Residue from the sample can impact the sensitivity of the sensing bulb and clog the junction. This is especially true if the sample has a lot of organic material. It is recommended to regularly soak your electrode in cleaning solution.

It is also recommended to:

1. Inspect the electrode for damage or scratches. If they are present, replace the electrode.
2. Inspect the cable. The connection cable and insulation must be intact.
3. Connectors should be clean and dry
4. Rinse off salt deposits with water or DI water.

Calibration - The pH sensing bulbs become less sensitive over time so make sure that you are calibrating regularly to keep your meter accurate. Also, calibrate after cleaning or a long period of storage.