A Spotlight on Chase BlH2Ock® Moisture Block Compound: Function, Application, & How to Clean.

Posted by Chase Corp Editor on Oct 16, 2020 7:56:02 AM
Chase Corp Editor
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Chase Block postChase BlH2Ock® is a flexible semi-conductive thermoplastic/semi-conductive mastic used for moisture protection in the conductor strand of medium voltage underground and submarine cables. To meet industry requirements for moisture blocking agents, the compound is designed to prevent ingress and longitudinal migration of water within the stranded core of power cables. If CBH is properly applied, the cable will meet water penetration test ICEA T-31-610.

Chase BlH2Ock® is melted and pumped out of fiber or steel drum packaging using heated drum unloaders (piston/platen type). Typically, once the material is heated to approximately 350 degrees F, it is pumped through heated hoses and generally through a ball valve and then applied directly onto the strand just before the material passes through a compression die to wipe off excess CHB. Passing through the die allows the application of a thin coating to the strand and the filling of the interstices between the wire strands as the cable is processed through each stranding operation. Once the Chase BlH2Ock® mastic cools, it becomes a flexible solid barrier, preventing ingress and longitudinal migration of moisture into the cable and along the strand.


One of the features of the compound is that it adheres extremely well to the conductor strand (either copper or aluminum). However, this can make it a challenge to clean or remove the compound as needed for splicing, termination, etc. For best results, cable manufacturers should consider an ultrasonic cleaning chamber and/or use a cleaning solvent such as LPS PF® Solvent available from ITW Pro Brands (4647 Hugh Howell Road, Tucker, GA 30084, www.Ipslabs.com, 800-241-8334). Toluene is also a very effective cleaning solvent, but it is a hazardous material and must be used with proper ventilation and protective equipment.

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Topics: Wire & Cable, BlH2Ock®, Moisture blocking materials