Like all M. C. Miller products, our IR-free coupons are built to last. The wire/coupon interface is environmentally sealed to keep the steel, copper, and solder components corrosion-free, making the coupon virtually indestructible.
M. C. Miller IR-free coupons can be easy installed using standard installation practices near existing test stations (see NACE Standard RP0104-2004). The M. C. Miller 2 inch diameter PVC coupon holder is a convenient way to couple a coupon with a length of 2 inch diameter PVC tubing which is typically used to shield a reference electrode positioned above the ground (inside the exposed tubing) from stray potential gradients.
After an IR-free coupon has had time to polarize (after being connected to a structure under CP protection), which can take about 1 month, a reference electrode can be inserted into the top of the shielding PVC tube, contacting the compacted soil above the coupon. A high input impedance voltmeter can then be connected between the coupon (via its test station terminal) and the reference electrode. An IR-free potential reading (an accurate polarized potential) is then obtained by breaking the connection between the coupon and the structure, typically via a switch, thus interrupting cathodic protection to the coupon. A coupon-to-soil potential measurement is then taken immediately after breaking the coupon-to-structure connection.