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TMCO HYDRAULIC SERVICES – BACKFLOW PREVENTION

TMCO HYDRAULIC SERVICES – BACKFLOW PREVENTION. HOW DID TYPICAL BACKFLOW PREVENTION DEVICES PERFORM THROUGH THE CHCH EARTHQUAKES?. PRESENTED BY: MIKE BAKER. introduction. Speaker: Mike Baker TM Consultants Ltd EECA FUNDED 35 staff All services All projects All locations.

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TMCO HYDRAULIC SERVICES – BACKFLOW PREVENTION

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  1. TMCOHYDRAULIC SERVICES – BACKFLOW PREVENTION HOW DID TYPICAL BACKFLOW PREVENTION DEVICES PERFORM THROUGH THE CHCH EARTHQUAKES? PRESENTED BY: MIKE BAKER

  2. introduction Speaker: Mike Baker TM Consultants Ltd EECA FUNDED 35 staff All services All projects All locations

  3. ENCLOSURES AND DEVICES University of Canterbury installation.

  4. ENCLOSURES AND DEVICES Note seepage caused by silt or blockages

  5. ENCLOSURES AND DEVICES Sturdy enclosure Clearance under doors to allow adequate runoff

  6. BACKFLOW DEVICE overview No external damage to backflow preventers Foundation pad, thrust blocks and enclosures performed well Leaky devices caused by non-localised liquefaction and small stones Most problematic devices simply required a cleanout Few devices required new parts Steel spools through slab helped with above slab stability

  7. Encountered damage in cracked seats for the devices, more prevalent after earthquakes Possible water hammer and increased pressure resulting from earthquakes damaged devices Hairline cracks in balls causing leaks Increase in particles and stones from mains pipework blocking devices BACKFLOW DEVICE overview

  8. INSTALLATION High mass valve assembly support was critical to avoiding damage.

  9. PIPING Pipe work was the main issue with damage to backflow assemblies being secondary to this.

  10. OTHER ISSUES Illegal temporary unprotected connections were prevalent. Many still remain. - Backflow did occur, witnessed by foaming in broken street mains near commercial/industrial buildings. Maybe backflow from inadequate air gaps. Frost protection, particularly for those devices unused over winter (spring, cartridge, test cock failures). Water hammer theory.

  11. OVERALL Installation-wise I believe we are doing well. Rigidity and support are key. Keeping silt, stones and other debris out of the system is important. Frost protection, particularly for those devices unused over winter (spring, cartridge, test cock failures). A TA check up on existing systems would be prudent to check for illegal systems.

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