A Quantum Leap in Technology: SensoGate

The unique modular system from Knick for innovative manual and pneumatic retractable fittings. Also ideal for hygienic applications.

Manual versions, variants for use with simple commercial control units, or fully automated quality solutions – the flexible sensor lock-gates in the SensoGate series offer a multitude of advantages and enable swift amortization through considerable time and cost savings.

All SensoGate fittings are also available as hygienic versions and as versions for hazardous locations (marking: II 1 GD c II).

Design Innovations

More than a dozen patent registrations speak for themselves – with the SensoGate series of sensor lock-gates, Knick succeeded in markedly improving the previously practiced principle of the push rod mechanism. The results are as pioneering as they are customer-friendly: over seventy percent time savings in initial installation and replacement of wearing parts compared to other devices. The benefits of genuine and unique modularity are seen here: for example, the immersion tube can be replaced in a single movement – without removing the entire fitting. The drive unit with the immersion tube can be disconnected from the calibration chamber and the process adaptation by loosening a single coupling nut.

Exemplary Modular Design

The sophisticated design reduces stress on seals and ensures an increased service life. Divided calibration chambers enable especially easy replacement of the process seal. Complete modularity simplifies the installation and allows replacing different components such as the drive or the immersion tube without disassembling the unit. You can easily switch to other types of electrodes, other process adaptations or immersion depths. Virtually all maintenance work is easily done on the site.

The sensor lock-gates, sophisticated down to the smallest detail, allow for cleaning and calibration of the sensor without interrupting the process. A quick exchange during the running process can be done without difficulty.

Quick Replacement

All gaskets can be accessed and replaced quickly and easily thanks to the separability of the calibration chamber and the simple tools required. This is also helped by our special installation tools.

A Question of Material

Today, conventional retractable fittings are available in the widest range of materials: PP, PEEK, PVC, PP, steel, Hastelloy, titanium etc.

Plastics frequently provide advantages to resist chemical stresses, but these have been out-weighed to some extent by the disadvantages of the designs: They are thermally instable, tend to swell and therefore do not have enough dimensional stability. In particular, immersion tubes made of plastic are greatly limited in terms of their application, cannot move after swelling and often malfunction at an early stage.

Processed Plastics

By contrast, the plastic versions of the SensoGate are reinforced with carbon fiber. In addition to the chemical resistance of the reinforced PEEK, PVDF, or PP, the calibration chamber and the immersion tube retain their shape, even when exposed to higher temperatures. The immersion tubes made of carbon-fiber-reinforced plastic are injection-molded rather than cut so as to avoid tool marks. The advantage of this method is that all the fibers remain covered by the surface. Cutting such fiber-reinforced plastics on a lathe would expose fibers and the resulting surface would be too rough for the O-rings to slide over.

Attractive in Every Way

The result of Knick’s injection-molding is a straight pipe with a cohesive surface of excellent quality. The direct benefit for the customer is the minimal O-ring wear and the correspondingly long service life of the gaskets. At the same time these materials can also be used at a great cost advantage where until now serious chemical stress combined with high pressures and temperatures have required extremely expensive materials such as Hastelloy. In addition to the financial aspect, a further major advantage are the carbon fiber reinforced plastics used by Knick with thermal expansion characteristics similar to those of steel. There are thus no longer any pressure restrictions on the permissible temperature range, due to the division into pressurized components made of steel and process-wetted materials made of carbon-fiber-reinforced plastic. The pressure stability is the same at room temperature as it is at 120 °C/140 °C.

Furthermore, the conductivity of plastic carbon-fiber-reinforced components especially suit the use of SensoGate in hazardous areas. The sensor protection made of conductive plastic prevents the electrodes from building up electrostatic charge and, in turn, distorting the measurements.

Process Adaptation

SensoGate retractable fittings can be adapted to various processes with a steel flange 1.4571 DN 32 to DN 100, dairy-pipe screw joint DN 50 to DN 100, ANSI 316 1 1/2″ to 3″ flange and Ingold sockets, or hygienic process connections. Other special adaptations – such as for flow cells – are possible.

SensoGate H
Safe Separation and Still Hygienic

SensoGate H are the only retractable fittings on the market which combine hygiene and safe separation from the process. When retractable fittings are used in processes in the pharmaceutical and food industries, with their high hygienic requirements, further demands arise with regard to sterilizability. Unlike other conventional fittings on the market, not only the process side but also the calibration chamber has been hygienically designed in the SensoGate. This means that its suitability for unrestricted use in pharmaceutical and food applications has been attested. This also allows validation in FDA-regulated production processes.

Setting the Seal

Previously, the combination of demands for a hygienic-compliant fitting and safe disconnection of the calibration chamber from the process was considered unfeasible. While nonhygienic process fittings frequently feature two or even three process seals for reasons of safety, this was previously not possible for hygienic lock-gates as the space between the seals cannot be rinsed and is therefore not hygienic. However, the consequences of the sealing principle are insufficient safety and a high level of wear to the seal. During movement of the lock-gate, the connection from the process to the inlet and outlet of the fitting is open; the risk of recontamination to the process is consequently high. In contrast to this, this presents no problems for the SensoGate. The new, patented lock-gate principle for the first time allowed us to create a hygienically certified retractable fitting safely cut off from the process during all movement.

Best Cleaning Results

The process-side O-ring gasket which fits flush and free of dead spots in the process adaptation can be rinsed by not only the process but also from the interior of the fitting. A special molding on the inner side ensures that the flow of rinse and sterilization medium is directed toward the interior of the gasket. This means that it is possible to clean the interior of the process connection and the exterior of the immersion tube all the way down to the process seal.

Three high pressure nozzles arranged tangentially on the sensor ensure an optimal cleaning effect, triggering a cyclone circumflowing the sensor and stripping away impurities at high speed. The cleaning medium or hot steam for sterilization are supplied directly at the media connection, through an integrated check valve decoupled from the regular media connections of the multi-plug. This valve also has no dead spots and is easily accessible.

Extended Immersion Depths by Offsetting the Process Adaptation

The hygienic SensoGate variants also enable immersion depths not achievable with conventional hygienic fittings. As only the part of the immersion tube may be inserted into the process which was previously sterilized in the calibration chamber, immersion depths of more than 20 to 26 mm were formerly a problem. By contrast, immersion depths of 32 mm or 57 mm can be selected with SensoGate H fittings. As a result, 220 % of previously possible immersion depths is in future available for installation in flow cells and especially for installations in which every millimeter counts, e.g. in double walled tanks. This is achieved solely due to an adjustment of the process adaptation on the calibration chamber, while the rest of the structure remains the same. Once the sensor is inserted into the process, the immersion tube and calibration chamber can also be cleaned in this position down to the process seal and, where required, sterilized. For the first time, contamination from the rinsing chamber into the process while moving can be safely prevented with this solution, even after long measuring intervals. Retrofitting is also possible.