Knick Germany, the inventor of Ceramat has launched SensoGate - the pioneering sensor lock-gate for process sensors like pH, Conductivity and Dissolved Oxygen.
The tried and tested Ceramat sensor lock-gate retractable fitting is the solution of choice for processes with demands due to wear and corrosion. For many applications, however, the expense of a ceramic fitting is not necessary. For this reason, Knick has developed SensoGate, a new type of retractable fitting for the medium-priced market segment.
Normally, the sensor moves through an O-ring lock-gate into the process and back. The resulting mechanical load is frequently aggravated by thermal and/or chemical stress, which leads to the O-rings swelling up. The immersion tube and/or the sensor holder can also become coated with sticky layers, interfering with the movement of the sensor.
Knick has combined the superior principle of internal O-rings with a new patented lock-gate that provides superior functionality over products currently on the market.
Unlike conventional methods, the new system also has a sealing against water and primary water rinsing function, as well as a protective rinsing function. The latter prevents any of the process medium (e.g. fibers or particles) from getting between the O-rings and the immersion tube, when the sensor is moved in and out of the rinse water. This function helps the O-rings in the SensoGate subjected to much less load than O-rings in conventional retractable fittings, and availability of the measuring point is increased significantly.
The unique, compact design offers genuine plug-and-play installation without fiddly hose connections and a confused tangle of hoses. There is one single central connection for the new sensor lock-gate, the multiplug, which has already proved its worth in the Ceramat. The multiplug keeps everything in order: the buffer solution and cleaner with all stop valves, compressed air, and limit position switches. Each fluid travels through individual tubing to prevent entrainment.
Cost savings in service and spare parts
The maintenance of an O-ring process gate was frequently a problem in the past and ease of maintenance was a top priority in developing SensoGate. In many processes, for example, when the boiler where the sensor is located happens to be full, it is impossible to remove the fitting to perform maintenance. In this case, because a malfunction or a leak cannot be tolerated during the process, the operator often replaces the O-rings at regular intervals as a precautionary measure, rather than waiting for wear to occur. The time spent removing the fitting and repairing it in the workshop has to be added to the cost of a new set of O-rings.
The well-thought-out design of SensoGate guarantees that the technician can quickly reach all relevant parts on site, without having to return to the workshop with the sensor lock-gate. Parts are replaced only as needed. In the case of a broken electrode, the front electrode sealing ring is frequently cut by broken glass. Previously, replacing the seal and removing the splinters from the calibration chamber called for comprehensive dismantling of the fitting. This is not required with the innovative SensoGate design.
Maximum process safety
SensoGate sets new standards in this field as well. Through the arrangement of the O-rings, at no time is there any connection between the drain opening of the rinsing chamber and the process, not even during the stroke movement. The process medium cannot escape, either into the drive unit or outwards. The point of separation between the stroke cylinder and the calibrating chamber is double sealed and ventilated. This prevents media from escaping from the calibrating chamber into the stroke cylinder, and conversely prevents compressed air from entering the calibration chamber and falsifying the calibration. After all, what is the use of an EHEDG certificate, if the medium can run into the stroke cylinder and micro-organisms find ideal growth conditions there?
Even inadvertently, almost nothing can go wrong with the SensoGate. The sensor can only be dismantled in the service position. SensoLock reliably blocks the movement of the fitting and prevents it from moving into the process position without the sensor. Furthermore, the stroke cylinder and the immersion tube are secured against twisting, which guarantees constant flow conditions for the sensor monitoring the process.
Improved immersion depth
The novel lock-gate principle of SensoGate allows a greater sensor immersion depth, compared to existing retractable fittings. Even with an immersion depth of 88 mm for the immersion tube, the effective immersion depth of the sensor is 65 mm measured from the lower edge of the fitting flange to the tip of the electrode. This guarantees that the sensor is reliably immersed in the process medium beyond the dead flow volume of the single-ended flanged nipple. In existing retractable fittings, the immersion depth is often measured from the side of the fitting flange facing away from the process. The effective immersion depth of the sensor is thus reduced by the flange thickness. For even greater immersion depths, for example, for use in coated and thermally insulated boilers, Knick is working on a version with an immersion depth of 125 mm. All immersion depths are achieved with a short sensor length of 225 mm, which makes the use of expensive, 425-mm long glass electrodes superfluous. Handling becomes easier and the likelihood of a broken electrode is significantly reduced.
Cyclone rinsing for optimum cleaning
A further problem of existing retractable fittings is the inadequate rinsing and cleaning effect in the calibration chamber because the inflow and outflow are located opposite each other. This always leads to the formation of shades at the sensor.
By contrast, SensoGate has a highly effective sensor cleaning system. The inflow holes are arranged like nozzles in a ring around the sensor head. The special arrangement means that the rinsing fluid is injected tangentially and that a rotating flow is created around the sensor. Fluid exits the sensor through the drain, which is also ring-shaped.
The entire design is modular and consists of only a few parts; in this way, process-wetted elements of different materials can easily be used (1.4571, 1.4435, PVDF, PEEK). The drive unit with its stainless steel cylinder is always the same and guarantees consistent, mechanically high quality. Many different process connections can easily be implemented with SensoGate. The innovative sensor lock-gate is designed for use with gel as well as with refillable liquid electrolyte sensors.