The MK IV is designed primarily for laboratory or workshop use, but is IP54 rated and rugged for site use as well.

Alternating Current Potential Difference (ACPD) is a crack sizing technique which can be used for monitoring and measuring fatigue crack length and depth. It has been used for monitoring crack extension in laboratory tests and also for surface crack shape evolution studies.

In TSC equipment the current input and voltage measurement functions are kept apart. This allows the current input points on probes to be widely separated which produces a more uniform electric field (and hence more accurate sizing), and also allows many voltage probes to be associated with a single input current for monitoring purposes.

The MK IV ACPD instrument can be used for a variety of crack sizing applications, including:

• Welded connections, butt welds, tee butts, tubulars, pressure vessels (refinery, nuclear, offshore topside and underwater)
• Threaded connections, nuts, bolts, drillstring threads, large diameter threads
• Automated inspection using tracking systems, robots
• Monitoring of cracks to give crack growth data
• Monitoring of critical regions for crack detection

The MK IV ACPD instrument is designed for laboratory use, or in controlled monitoring environments. It is available with built in multiplexing as an option capable of extension to 128 channels and 4 output currents.