The 3H-type cell adds a separate reference compartment to the H-type membrane cell. The cathode and anode are separated by an ion exchange membrane while the reference electrode is protected in its own compartment and measures right next to the working electrode. The reference electrode sits in a separate third compartment connected to the working compartment through a Luggin capillary with a tip opening below 0.2 mm (manufacturer data). Bringing the tip close to the working electrode reduces the ohmic (iR) error in the measured potential; do not place the tip closer than about twice the capillary diameter. Agar can be added to the capillary to slow electrolyte exchange.
The reference compartment is closed with an internally threaded cap. Keep it closed during measurement; otherwise liquid flows between compartments by the communicating-vessels effect. The flanges of the two compartments are joined with a chain clamp; opening the clamp lets you change the membrane in minutes. The PTFE inner core of the lid rotates 360°; electrodes are usually aligned parallel to the membrane.
In the standard-sealed cell, the lid and electrode feedthroughs are closed with O-rings and sealing screws. An oxygen-free atmosphere is maintained by purging with nitrogen or argon. It is not intended for vacuum or pressure.
The body is made of borosilicate glass 3.3, which has low thermal expansion (3.3 × 10⁻⁶ K⁻¹) and the highest resistance classes against water (HGB 1) and acids (S 1). Avoid sudden temperature differences above 120 °C to reduce the risk of breakage.
In the jacketed (double-layer) version an outer water jacket surrounds the inner cell. Water from a circulating thermostatic bath flows through the jacket via hose connections and keeps the electrolyte at a constant temperature during the measurement.
| Cell type | Three-compartment (3H), standard-sealed |
| Temperature control | Water jacket for a circulating thermostatic bath |
| Body | Borosilicate glass 3.3 |
| Luggin capillary | Tip opening < 0.2 mm (manufacturer data) |
| Reference compartment | Closed with internally threaded cap |
| Compartment joint | Flange + chain clamp |
| Electrodes | Long type required |
| Volume options | 5-10 mL, 30 mL, 50 mL, 100 mL, 150 mL, 200 mL, 250 mL |
| Not included | Electrodes and membrane (sold separately) |
A sampling port can optionally be added to the cell body; please mention it in your quotation request.
Electrodes and membranes shown in the photos are for illustration only and are not included in the price. Compatible reference, counter and working electrodes and membranes are available in the Electrodes category of our site.
For volumes, dimensions or port layouts other than those listed, you can request a custom-made quotation through the Quotation Form.
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