Ref-Check VPR (Voltage Potential Restoration) Test Instrument by Farwest Corrosion

No CP Technician should be without this instrument!

Cathodic Protection (CP) solutions require accurate voltage potential or structure-to-soil readings. The Ref-Check VPR is the next step in the Farwest Ref-Check product line designed to overcome false or low potential readings from a cathodic protection reference electrode (CPRE).

The Ref-Check VPR can take accurate potential readings even with a compromised CPRE, which no longer requires replacement. You can now trust the provided potential reading even if the CPRE is not performing to original specifications.  In addition, the Ref-Check VPR can confirm good contact-to-earth resistance of a portable CPRE and/or CP coupon.

The Ref-Check VPR works in conjunction with a standard digital multimeter (DMM) via the included dual banana plug cord. When engaged, the Ref-Check VPR increases the circuit input resistance from 10 million ohms to approximately 5 billion ohms, making it over 500 times more sensitive.  This allows a standard DMM to provide much higher accuracy because, with the Ref-Check VPR, it provides near zero meter loading.

In addition, when connected to the DMM, the Ref-Check VPR remains out of the circuit until the "Press to Read" button is engaged.  This allows a CP technician to leave the Ref-Check VPR connected to the DMM during normal CP testing.

Background

All DMMs will impose a load, referred to as "meter loading”, on the CPRE.  This load affects CPRE accuracy even under the best conditions.  Most professional grade DMMs have a 10 meg (million) ohm input resistance.  This may seem high but when used to measure very sensitive (high resistance) circuits, such as a compromised reference electrode (due to age or lack of moisture), the meter imposes a load on the circuit that can result in a very large structure-to-electrolyte potential error.