The danger of moisture getting into a system of contact links between the electrode, cable and transmitter is a common concern when measuring pH. The electrical resistance produced can lead to unavoidable measurement errors or, at worst, total system breakdown.
The Endress + Hauser TOP 68 system provides IP68 compliance for the connection between a pH electrode and its transmitter. When fitted, moisture and dirt cannot interfere with the accuracy and reliability of readings.
Total operational protection (TOP) refers to an absolutely watertight system, which has been achieved thanks to an innovative plug-in design, the use of moisture resistant raw materials and a high-precision sealing system.
Plug-in pH sensor systems have great difficulty complying to IP 67 and often require up to four O-rings, which are fitted in an attempt to provide an adequate seal. TOP 68’s novel plug-in system means that only two O-ring seals are required and the system is sealed at the moment the connector comes into contact with the O-ring. The union nut no longer has a sealing function and so can turn easily.
The cable bushing features twin sealing lips, which optimise leak-proofing and provide strain relief. The pressure resistance of up to 25 bar means that process substance leaks can be reliably contained – even in the event of the electrode becoming detached.
The contact housing of TOP 68 is made of water-resistant PFA, which guarantees long-term high impedance – vital for plant systems with sources of damp or water spray. TOP 68 also has a PPS plug connection system, which is equipped with a tongue and groove guide. This ensures that any mechanical stress is placed on the hard PPS material, leaving the PFA plug-in fully protected. The guide system also ensures accurate positioning of the plug, even in the dark! Gold-plated nickel contacts are welded into the PFA housing, with short spring travel lengths to guarantee reliable and consistent contact operation.
TOP 68 is available in two, four and six-pole versions and its modular configuration allows the system to be adapted for use with either gel or liquid electrodes. The modular, screw-in design makes TOP 68 suitable for fitting to virtually any process plant assembly.