WTW SenTix H analogue special-purpose pH electrode, ground-glass diaphragm, S7 connector, 103644

With the WTW SenTix H, the user sets the electrolyte outflow themselves: a thread on the ground joint diaphragm can be adjusted with the special key, which is included according to the WTW instructions. The analogue glass electrode is refillable and has an S7 plug head. WTW names it for highly alkaline samples and for samples with a high salt concentration.

Adjustable ground joint instead of a fixed junction

The glass shaft has a diameter of 12 mm; the membrane is cylindrical. The reference electrolyte is 3 mol/l KCl, Ag+-free. The refill opening remains open during calibration and measurement, with the electrolyte level at least 2 cm above the sample level. With the ground joint diaphragm, the minimum immersion depth also has to be observed. How far the ground joint is opened determines the electrolyte outflow; the adjustment is described in the WTW instructions. The membrane resistance is below 2 GΩ; measurements are taken from 0 to 14 pH.

Typical applications according to WTW

• Highly alkaline samples and diluted alkalis
• Samples with a high salt concentration
• Emulsions and suspensions
• Sulphide-containing liquids
• Cooling water, dye solutions and electroplating baths
• Bleaching lye

Connection and alternatives

The electrode is supplied without a cable. Depending on the measuring instrument, one of the WTW connection cables AS/DIN (1 m, 108110), AS/DIN-3 (3 m, 108112) or AS/BNC (1 m, 108114) fits. A temperature sensor is not built in; the temperature is either entered on the measuring instrument or measured using an external sensor. For low-ionic-strength media, WTW offers the SenTix HW with the same design.

Storage and care

Before taking the first measurement, remove the wetting cap; gas bubbles behind the membrane can be removed by shaking. For short measurement breaks, immerse the electrode in reference electrolyte (KCl 3 mol/l, Ag+-free) with the refill opening open. Overnight and for longer periods, it stays in the wetting cap, filled with reference electrolyte, with the refill opening closed. According to WTW, storing the electrode in a dry state or in deionised water can cause permanent damage. If the cap has dried out, the electrode needs at least 24 hours in reference electrolyte. As with any pH electrode, strong acids and alkalis, hydrofluoric acid, organic solvents, oils, fats and proteins shorten its service life.

Technical details

Scope of delivery

• 1 WTW SenTix H pH electrode with wetting cap
• Special key for the ground joint (included according to the WTW instructions)
• Dropper bottle for refilling (included according to the WTW instructions)
• No connection cable in the scope of delivery

Accessories and procurement service

Connection cables (AS/DIN, AS/DIN-3, AS/BNC), KCl 3 mol/l reference electrolyte and buffer solutions for calibration are also available. The procurement service can answer any questions regarding the appropriate ground-joint electrode.