Pressure Cell

When properly installed and protected against lightning and surge damage, the core sensing element should last decades. The main failure modes are cable damage during fill placement and water ingress at the gland seal; we address these by offering reinforced cable armor and factory-tested pressure-tight connectors. Many units in our reference list have been functioning for over 15 years with stable zero drift.

Yes, as long as the cell is specified for the expected stress levels during both phases. For instance, during heavy compaction you might temporarily exceed the long-term design stress; select a range that covers these transient peaks without losing resolution on the lower operational readings. We can advise on the trade-off between range and sensitivity based on your load history.

Hydraulic cells are often preferred for dynamic stress measurement and in environments where electromagnetic interference is high. Vibrating wire cells are favored for long-term, static monitoring because the frequency signal is inherently stable over long cables and immune to resistance changes. Kingmach manufactures both types, and we can help match the sensor to your data acquisition infrastructure and project duration.

The key is to ensure the sensing face sits exactly at the excavated profile, directly against the rock or soil. We provide a protective mounting frame that keeps the cell in position during spraying and prevents the shotcrete from bridging over the cell. Also, the cable must be routed away from the nozzle path to avoid tearing. Our installation guidelines include sketches for common tunnel cross-sections.

Every cell is supplied with a calibration sheet showing the applied pressure vs. output at multiple load points, traceable to international standards. We can also provide a factory certificate if your contract requires it. For critical projects, we recommend a field validation using a hydraulic load test against a reference gauge.