DCVG Surveying

Swain DCVG Product Line

DCVG equipment is now available. This equipment has been developed following extensive research, based on field surveys and customer interaction which is ongoing to ensure the industry benefits in improved quality control and pipeline coating integrity assessment. Equipment is supplied in heavy duty padded field case to ensure safe transportation. Electronic components in meter, switcher and bias boxes are subject to a 12 month warranty period.


The DCVGM has been designed specifically for detecting and quantifying coating defects using the proven DCVG technique. Rugged construction employing quality components ensures reliable operation in the harshest testing environments.

This instrument features extremely high input resistance, allowing measurements in very arid locations. Reliability has been extended through a panel meter designed for military field equipment, gold-plated connectors, duplicated switch-contact redundancy, and intelligent battery management circuitry.

BIAS and Probes

The DCVGM probe consists of a Bias 1200 Box and a non-polarisable probe. The probe and control box consists of three separate sections which are screwed together, as a standard compact set. The probes are also available as one piece as these are more suited to more arid conditions. The bias box contains 1 x AAA rechargeable battery to supply the bias source. Switched and variable controls allow bias adjustments between -1200 and +1200 mV.

The non-polarisable probe is a multi-wrapped fiberglass construction reinforced with carbon fiber with fittings machined from PVC, brass, and stainless steel to ensure long and reliable serviceability.

Swain DC Interrupter

The Swain DC Interrupter utilizes solid-state techniques to provide the DCVG signal required to detect Coating Defects on buried pipelines. By connecting the interrupter in series with the DC output of Cathodic Protection Rectifiers, or storage batteries, the electronic switch generates the DC pulse required for DCVG testing. Using a high-power MOSFET device, the switcher is capable of switching loads from milliamps to 30 amps DC. The unit has three duty cycles and can also be used for “on-off” cathodic protection surveys. Powered by an internal sealed lead acid battery, the unit is capable of continuous operation for up to 7 days between chargers. The 4 stage battery management circuitry ensures hassle free charging without the possibility of overcharging or the “memory effects” associated with NiCad technologies.

Available Components

    • DCVGM
    • Bias 1200
    • Swain DC Interrupter
    • Non Polarisable Probes
      • Available in 1 and 3 pieces
    • Silicon Test Leads
      • Available in custom lengths
    • Charging Brick
    • Harness
    • Hardware
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