WTW digital IDS pH electrode SenTix HW-T 900, ground joint, 1.5 m fixed cable, 103753

For low-ion media, emulsions and suspensions, WTW has provided the HW-T 900 series with ground-joint junction. With the WTW SenTix HW-T 900, the electrolyte outflow can be adjusted via a thread using the special key that is included according to the WTW instructions. The electrode is a digital IDS pH electrode made of glass, and its calibration data is stored in the sensor. It measures from 0 to 14 pH at sample temperatures of 0 to 60 °C.

Adjusting the ground joint

For commissioning, the electrode is held with the membrane pointing down, and the ground joint is opened with the special key until electrolyte visibly emerges and the ground joint is completely wetted. It is then closed carefully until the rubbing of the rough ground surfaces can be felt as resistance. According to WTW, this may only be done with little force, otherwise the ground joint is damaged. For higher outflow rates, it can be opened further.

Electrolyte and immersion depth

The reference electrolyte is KCl 3 mol/l, Ag+-free, and refillable. The refill opening stays open during calibration and measurement. The ground-joint junction must be fully immersed in the solution, and the electrolyte level should be at least 2 cm above the level of the solution. The shaft diameter is 12 mm, the membrane is cylindrical, and according to the product page the membrane resistance is below 600 MΩ. An NTC temperature sensor (30 kΩ) is built in.

Typical applications according to WTW

• Low-ion media: boiler feed water, condensate, distilled and demineralised water, rainwater
• Emulsions, suspensions and liquids containing sulfide
• Cooling water, dye solutions, electroplating baths, salt solutions, lake water, surface water and seawater
• Soil extract, coffee extract, beer, lemonade, fruit juice, vegetable juice, wine, mineral water, milk, yoghurt, quark, honey, jam and vinegar
• Hair dye, mouthwash, shampoo and household cleaners
• Enzyme solutions, gastric juice, infusion solutions, protein-containing liquids, serum, Tris buffer solutions and urine (pharma, biology, medicine)

The last group is an application category according to WTW and not a statement on suitability for medical devices.

Connection

The SenTix HW-T 900 has a permanently attached 1.5 m cable with a waterproof IDS plug (4-pin, lockable).

Refilling and storage

If the level drops, reference electrolyte is topped up with the dropper bottle, which is included according to the WTW instructions. During short breaks, the electrode stands in reference electrolyte with the refill opening open; overnight, it stays in the wetting cap filled with it, and the opening is then closed. Do not store dry or in deionised water. According to WTW, salt deposits on the cap and closure do not affect the measurement and can be removed with deionised water.

Technical details

Scope of delivery

• 1 WTW SenTix HW-T 900 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)
• Operating instructions
• Fixed cable 1.5 m with IDS plug, permanently attached to the electrode

Regulatory information

As an electrical device, the digital IDS electrode falls under the ElektroG. The manufacturer Xylem Analytics Germany GmbH (WTW brand) is registered under the WEEE registration number DE 29884659. How to return old appliances is described on the page Environment and disposal.

Accessories and procurement service

Also available are reference electrolyte KCl 3 mol/l for refilling and buffer solutions for calibration. Enquiries about further IDS electrodes go through the procurement service.