Hanna HI6221 Advanced Benchtop pH/ORP Meter, 5-Point Cal

Hanna HI6221 advanced benchtop pH/ORP meter

The Hanna HI6221 is a laboratory benchtop pH and ORP meter with selectable resolution down to 0.001 pH, five-point calibration and a temperature input for automatic compensation. It is supplied as a starter kit with an HI1131B glass-body pH electrode and an HI7662-TW temperature probe. Seven Star LLC is an independent supplier in Muscat and is not affiliated with the manufacturer.

The part number is the instrument itself; the kit adds an electrode holder, buffer sachets, cleaning solution, 3.5 M KCl electrolyte, a capillary pipette, a 24 VDC power adapter and a USB-C cable.

HI6221 technical specifications

How the HI6221 works

A glass pH electrode produces a potential that depends on hydrogen-ion activity; the HI6221 measures it with a high-impedance input, applies the slope and offset from calibration and corrects for temperature. In ORP mode the same electrode input is used with a redox sensor and reads relative millivolts.

Calibration is the real strength of the instrument. With up to five points from eight standard buffers or five user buffers, the operator can bracket a narrow production range or span acid to alkaline solutions. Choosing the lowest resolution suits routine control; the 0.001 pH setting is for work where the electrode and sample warrant it.

Where HI6221 fits: sensors, accessories and related models

The HI1131B electrode and HI7662-TW temperature probe are supplied. The calibration starter kit includes pH 4.01 (two sachets), 7.01 (four) and 10.01 (two) buffers, HI700601 cleaning solution, HI7082 3.5 M KCl electrolyte, an HI764060 electrode holder and a capillary pipette. USB-C connectivity moves the meter into a laboratory data workflow.

Portable users should look at the HI8424 for field work; the HI6221 is for the bench.

HI6221 family comparison

Pick the HI6221 for quality-control and research benches, the HI8424 for plant walks, and a multiparameter meter such as the HI98195 for sampling across sites.

Selection and ordering checklist for HI6221

• Decide on resolution: 0.1, 0.01 or 0.001 pH
• Confirm the buffer set matches your calibration range (eight standards plus five custom)
• Check electrode suitability for your samples; other Hanna electrodes may fit better for viscous or non-aqueous samples
• Plan spare electrodes, KCl electrolyte and buffers
• Confirm USB-C data export and power adapter requirements

Installation, calibration and maintenance of HI6221

Place the meter on a stable bench away from stirrers that heat the sample, fill the electrode with electrolyte if refillable as directed, and soak it in storage solution before first use. Calibrate with fresh buffers that bracket the sample, using at least two points and more if the application demands.

Rinse the electrode between samples, avoid touching the glass bulb and keep the electrolyte level topped up. Clean with the HI700601 solution when the slope falls, and replace the electrode when calibration slope or response time can no longer be restored.

A good laboratory routine records the buffer lots, calibration points and electrode serial in a log, and verifies the calibration with a check buffer during long sessions. When measuring at different temperatures, allow samples and buffers to equilibrate and keep the temperature probe in the sample so that compensation is genuine.

If the same bench is shared between technicians, define one standard calibration recipe so that results from different users are comparable.

Electrode care deserves a short written routine. After each session, rinse the bulb with deionised water, return the electrode to storage solution and never to deionised water, and check the electrolyte level. Once a month, inspect the junction, clean it with the cleaning solution if sluggish, and compare the response against a fresh pH 7.01 buffer. Keeping a spare electrode in the drawer means a failed sensor does not stop the laboratory, and a record of calibration slopes gives early warning of ageing before results are affected. When the meter is moved between benches, recheck that the temperature probe and electrode connectors are fully seated before calibrating again.

Typical applications of HI6221 in Oman and the GCC

In Oman the HI6221 suits quality-control laboratories at refineries, petrochemical and power plants, desalination laboratories verifying permeate and chemical dosing, environmental testing laboratories and university benches. Its high ceiling of 20 pH and low floor of -2 pH covers strongly alkaline cleaning solutions and acid regeneration liquors.

Laboratories that audit contractors or compare against field meters often keep a benchtop unit as the local reference, which is where five-point calibration earns its place.

Information to send with an RFQ for HI6221

• Quantity and any spare electrodes or temperature probes
• Buffers, electrolyte and cleaning solutions needed
• Sample type and temperature range
• Delivery location and lead time
• Project or tender reference

Documents and quotation

The instruction manual for the HI6221 is attached on this page for specifications, calibration procedures and maintenance steps.

Send the part number HI6221, the quantity and your delivery location and we will reply with availability and a quotation.