Hanna Instruments HI9813-51 Portable Combo Meter for pH, EC, TDS and Temperature
The Hanna Instruments HI9813-51 is a portable combination meter that measures pH, electrical conductivity (EC), total dissolved solids (TDS) and temperature with a single combination probe. It is ideal for agricultural, greenhouse, hydroponic and general water testing applications. By combining four measurement functions into one instrument, it allows users to measure different properties of a liquid without having separate meters for each parameter.
This meter is especially useful in checking irrigation water and nutrient solutions. pH is a measure of how acidic or alkaline a liquid is. EC is a measure of how well a liquid is able to conduct electricity, and gives an indication of the concentration of dissolved ions (including nutrients and salts). TDS = total dissolved solids and is an estimate of the concentration of dissolved solids, usually expressed in parts per million (ppm or mg/L). Temperature is also considered as this can influence the conductivity measurements.
How the HI9813-51 works
The HI9813-51 is equipped with the supplied HI1285-51 combination probe which contains a pH electrode, an EC/TDS sensor and a temperature sensor all in one polypropylene housing. The probe connects to the meter with an 8 pin DIN connector and 1 meter cable. The integrated design allows the user to switch between measurement functions without changing probes.
Each measurement tells us something different:
- pH: A measurement of the acidity or alkalinity of a liquid, ranging from 0.0 to 14.0 pH.
- EC: Electrical Conductivity measurement. mS/cm. Higher conductivity usually means higher concentration of dissolved ions.
- TDS: Calculates the concentration of dissolved solids in ppm (mg/L) by converting conductivity using a conversion factor.
- Temperature: Measures the temperature of the liquid and provides automatic temperature compensation for EC and TDS readings.
The LCD shows the measurement result and the selected parameter. Users can toggle measurement modes via dedicated buttons, and tutorial messages on screen guide users through basic calibration and measurement procedures.
Key features and practical applications
pH measurement in liquids
The pH measuring range of the meter is 0.0 to 14.0 with a resolution of 0.1 pH and an accuracy of ±0.1 pH at 25°C. These specifications are helpful for users to monitor changes in the acidity or alkalinity of water and nutrient solutions. pH is calibrated manually at one point using a pH 7.01 calibration solution.
Measurement of EC and TDS
The EC measurement range is 0.00 to 4.00 mS/cm (0–4,000 microsiemens/cm). The TDS range is 0–1,999 ppm (mg/L). Both measurements are accurate to ±2% of full scale as per the manufacturer’s specifications.
The meter automatically changes the conversion factor from EC to TDS from 0.56 to 0.78. The value shown is an estimate as TDS is calculated from conductivity not measured independently. If you are comparing readings from different meters you should take account of the conversion method.
Automatic temperature adjustment
The HI9813-51 automatically compensates for temperature changes in the EC and TDS readings as electrical conductivity is temperature dependent. The compensation factor is fixed at 2%/°C. This means that readings are more consistent when the temperature of the liquid changes, but it doesn’t eliminate all possible sources of measurement variation.
Construction of probe and resistance to electrical noise
The HI1285-51 probe consists of a polypropylene body and a preamplified pH electrode. It has a built-in amplifier to minimize interference from electrical noise created by equipment such as pumps, motors and lighting ballasts. This is useful in greenhouse and hydroponic situations where electrical equipment may be operating near points of measurement.
The pH electrode is gel filled and does not require periodic electrolyte refilling. The probe still needs to be cleaned, calibrated and stored carefully and correctly for reliable measurements.
Technical specifications
- Brand: Hanna Instruments
- Model: HI9813-51
- Type: Portable pH/EC/TDS/Temperature Combo Meter
- pH measurement range: 0.0–14.0 pH
- pH resolution: 0.1 pH
- pH accuracy: ±0.1 pH (at 25°C)
- pH calibration: Manual, 1 point
- EC measuring range: 0.00–4.00 mS/cm
- EC resolution: 0.01 mS/cm
- EC accuracy: ±2% of full scale
- EC calibration: Single point, manual
- TDS measurement range: 0–1,999 ppm (mg/L)
- TDS resolution: 0.1 ppm
- TDS accuracy: ±2% of full scale
- TDS conversion factor: Variable, 0.56–0.78
- Temperature measurement range: 0.0–70.0°C (as specified by the meter). Usable range may be limited by the probe.
- Temperature resolution: 0.1°C
- Temperature accuracy: ±0.5°C
- Temperature compensation: Automatic EC/TDS, 2%/°C
- Probe supplied: HI1285-51 combination electrode
- Probe connection: 8-pin DIN
- Probe cable length: 1 meter
- Power supply: 1 × 9 V alkaline battery
- Battery life: Up to 150 hours of continuous use
- Meter dimensions: 145 × 80 × 36 mm
- Meter weight: 230 g
- Operating temperature: 0–50°C
- Maximum relative humidity: 100% or less
- Warranty: 2 years, according to the manufacturer's listing
Compatible equipment and suitable applications
The HI9813-51 is intended for users who require several liquid measurements from a single portable unit. Typical applications are:
- Hydroponic systems: Measure pH and conductivity of nutrient solution.
- Greenhouses and nurseries: Monitoring irrigation water and dissolved nutrient concentrations.
- Agriculture: Evaluation of water consumption in irrigation and other liquid-based growing applications.
- General water testing: Comparison of pH, conductivity, and estimated dissolved solids in appropriate liquid samples.
The meter includes the HI1285-51 combination probe. Check replacement probes for exact model compatibility and connector type before purchasing. The HI1285-51 is equipped with an 8-pin DIN connector, so you cannot assume a probe with a different connector will be compatible.
Operation, maintenance and calibration
Calibration shall be performed as per manufacturer’s instructions prior to measurements. The pH function uses a pH 7.01 reference solution and the EC/TDS calibration uses the proper conductivity or TDS reference solution.
For standard measurements:
- Connect the HI1285-51 probe to the instrument.
- Calibrate the suitable measurement function as and when required.
- Rinse the probe in clean water between samples to reduce the risk of cross-contamination.
- Insert the probe into the sample as instructed in the manual and wait for the reading to stabilize.
- Select the measurement mode you need and record the result.
- Clean the probe and store according to the recommended procedures for the electrode.
The meter is water-resistant for use in demanding working environments, but should not be assumed to be fully waterproof or suitable for permanent immersion. Protection of the probe against impacts, contamination and inappropriate storage conditions should also be ensured.
Components included
The HI9813-51 package contains the following components (see ordering information from the manufacturer):
- Portable tester HI9813-51
- pH/EC/TDS/temperature sensor HI1285-51 combination
- Bottle of pH 7.01 calibration solution
- Sachet of 1413 µS/cm conductivity calibration solution
- 1500 ppm TDS calibration solution sachet
- 2 × sachets of electrode cleaning solution
- 9 V alkaline battery
- Instructions for use
The supplied calibration and cleaning solutions make initial setup and routine maintenance easier. Compare the contents of the package to the supplier’s current product listing, which may vary by market.
Important considerations when choosing the HI9813-51
The HI9813-51 is calibrated manually at a single point, rather than a more sophisticated multi-point calibration procedure. Its EC range is 4.00 mS/cm maximum, and its TDS display is 1,999 ppm maximum. If your application requires higher conductivity readings, more advanced calibration checks or more measurement parameters, then you will need a different instrument.
The HI9813-51 combines these measurements in a single portable device for routine pH, EC, TDS and temperature checks, while keeping calibration and operation fairly simple.
