WTW SenTix 42 Plastic PH Electrode with Gel Electrolyte and Temperature Sensor, BNC, 1 m Cable, 103637

The WTW SenTix 42 has a plastic shaft, a gel electrolyte and an integrated 30 kOhm NTC sensor. It measures from 0 to 14 pH and is designed for outdoor use.

Plastic shaft and gel electrolyte

The shaft is 120 mm long and 12 mm in diameter. A fibre serves as the diaphragm, and the membrane resistance is less than 1 GΩ. Instead of a liquid electrolyte, the SenTix 42 uses a gel. The temperature range, from 0 to 80 °C, is narrower than that of glass electrodes such as the SenTix 82, which is approved for use up to 100 °C.

Cable with BNC and banana plugs

The 1 m long fixed cable terminates in a BNC plug and a 4 mm banana plug. This is suitable for measuring instruments with a BNC input. If your instrument has a DIN input, the SenTix 41-3, for example, is a suitable option: it has the same gel design with a temperature sensor, but features a 3-metre cable with a waterproof DIN plug.

With or without a temperature sensor

The SenTix 22 has the same shaft, the same gel electrolyte and the same temperature range, but no temperature sensor. If you measure the sample temperature separately anyway, this model will suffice. If you want the measuring instrument to take the temperature into account automatically, choose the SenTix 42.

Calibration and measurement

Calibration is carried out in accordance with the meter’s instructions. Carry-over between the buffer solution and the sample is minimised by briefly rinsing the vessels with the solution that will be added next. During measurement, the stirring conditions should correspond roughly to those used during calibration, and the diaphragm should not touch the bottom of the vessel. The frequency of recalibration depends on the application; many measuring instruments provide a reminder via an adjustable calibration interval.

Commissioning, storage and cleaning

Before the first measurement, remove the wetting cap and set it aside, as it is needed for storage. Gas bubbles behind the pH diaphragm can be removed by shaking. Only the shaft should be immersed; the diaphragm at the lower end of the shaft must be completely submerged in the sample. During short breaks between measurements, the electrode should be kept in reference electrolyte (3 mol/l KCl, Ag+-free); overnight, it should be stored in the soaking cap filled with this solution. Storing the electrode in a dry state or in deionised water will cause permanent damage to the measuring chain. Grease and oil can be removed with water containing washing-up liquid; limescale and hydroxide deposits can be removed with 10 per cent citric acid. pH measuring chains are consumables, and hydrofluoric acid, strong alkalis, organic solvents or high temperatures will shorten their service life.

Typical applications

• Electroplating effluent, industrial effluent and effluent in general
• Aquarium water and swimming pool water
• Groundwater, lake water, surface water and seawater
• Household cleaning products

WTW buffer solutions are available for calibration in DIN/NIST and technical grades. These are complemented by the A pHLab/K plastic armature (item no. 903841), the STH 650 bench stand (item no. 109809) and the KCl-250 reference electrolyte (item no. 109705).

Technical details

Scope of delivery

• 1 WTW SenTix 42 pH electrode with rinsing cap

Individual requirements and procurement service

Buffer solutions, armouring, a stand, or questions about which SenTix is compatible with your measuring instrument: the procurement service at lt-laborhandel.com/service can help you choose and source the accessories.