5 key lessons when using Guided Wave Radar

Make sure the GWR is mounted directly into the vessel whenever possible, avoid standoffs as they can cause unwanted interference. If using a concentric probe (see fig 1 - where a rod is inside an outer tube with both attached to the probe), they are not influenced as the signal path is contained inside.  If in a plastic vessel use a metal plate or flange greater than 100mm diameter, this helps to ‘push’ the microwaves in the right direction. It’s said all the time, but it really is worth a look at the manual, ideally before you buy, it may save you time and further vessel modifications. And, once again a chat and sharing a sketch or drawing with a knowledgeable manufacturer can help you avoid some pitfalls you might not be immediately aware of. Finally be careful of installing rod probes in agitated vessels, even if it is nowhere near, as long-term fatigue from even a small process movement may cause issues with process seals and signals.  Make sure cables cant touch the sides or internal objects, always install them on an empty silo if measuring solids.

Figure 1 A concentric tube format device helps with poor installations like nozzles, but can be susceptible to highly viscous products or long term internal deposits and build up.

Careful of build up in any mounting nozzle, perhaps insulate it if it's a heated product that sublimates on cooling. Be especially careful if using a concentric tube format between rod and outer tube, or twin rods on high viscosity products,  these types of systems often have internal spacers, build up on these can also cause measuring errors and reading hang-ups. Use a single rod format whenever you can. Use minimal spacers (ideally just one at the end) if mounting in a stilling tube or bypass. Explore a contactless measurement format if its a high viscosity, contaminated product that is expected.

Figure 2: Guided Wave Radar installed in bypass with a Magnetic Float Level Indicator as a second technology and side mounted tuning fork switch alarm. These narrow tubes need spacers to ensure the rod is central, but be careful about build up on them.