Walk through a complete seal replacement of both the process and rinse wetted O-rings in the SensoGate WA 131 M retractable holder by Knick.
What You Need
In the previous maintenance video, we disassembled our retractable holder and prepped it for seal replacement. If you have not disassembled your SensoGate, please check out the link to the disassembly video. To replace the seals, you will need a disassembled SensoGate and a seal kit. This kit contains FKM O-rings for both the process and rinse wetted components. Many different seal kits are available in different materials.
I also have two small accessory tools to help aid in the installation of both the O-rings and the scraper rings. While not necessary for installation, these two tools are very helpful. You can purchase them separately. This seal kit contains a number of different O-rings, which are individually labeled by their size. It also contains a tube of grease, as well as an installation drawing which outlines the location of each O-ring and scraper ring. It’s important when replacing O-rings in the field, that this grease is utilized.
Process Connection
We’ll begin by installing the seals in the process connection and working our way upward. Inside the process connection, there are 3 O-rings and 1 scraper ring. The first O-ring I’ll install is located in the groove behind the scraper ring. This one is 23 x 2 mm in size. Next, I’ll install the 20 x 2.5 mm O-ring located in the middle of our process connection. Finally the large 40 x 2.5 mm O-ring will sit in the groove on top of the fitting.
To finalize the seal replacement in the process connection, I’ll install 1 scraper ring overtop of the O-ring in the bottom groove using the scraper ring accessory tool. To do this I’ll pull the two steel pins back on the accessory tool and place the scraper ring at the end. Pressing down the two steel pins to deform the scraper ring, we can easily insert the accessory tool into the bottom of our process connection. Letting go of the pins and removing the tool from the process connection properly aligns the scraper ring in the groove. We can then utilize the bottom of our accessory tool to form the scraper ring in place. That finalizes the seal replacement in our process connection.
Cleaning and Calibration Chamber
We’ll set the piece aside and move on to our cleaning and calibration chamber. Our seal kit also includes O-rings for the rinse wetted components. We’ll start by installing the two 8 x 1.5 mm O-rings on both our inlet and outlet fittings. The next set of O-rings are located inside the cleaning and calibration chamber. When replacing the two 20 x 2.5 mm O-rings, it’s very important that you do not misalign the O-rings in this chamber. This could lead to blockage of the cleaning ports.
I’ll be using this O-ring mounting accessory tool to assist us with the process. First, remove the pin and install the two 20 x 2.5 mm O-rings onto the grooves of the tool, then deform the O-rings and reinstall the pin like so. Now, insert the tool into the chamber until it bottoms out. Remove the pin and use it to press the O-rings into their proper grooves. Next, I’ll install the final 23 x 2 mm O-ring into the top groove of the cleaning and calibration chamber. Just like in the process connection, install the final scraper ring over top of this O-ring. The scraper ring accessory tool can be used once again to ensure proper installation.
Immersion Tube
Install the final 2 O-rings in our seal kit on the immersion rod and inside the immersion tube. Place the 13 x 1.5 mm O-ring here on the outer groove of the immersion rod. Lastly, a trick to installing the final O-ring inside the immersion tube is to place it over top of the sensor which is in our drive assembly. Then, reinstalling the immersion tube over the rod helps to properly seat the O-ring in place. This finalizes the seal replacement. The SensoGate is now ready to be reassembled and put back into service.