Non Destructive Testing methods are used as part of water leak investigations in buildings. They are also used with new construction to verify waterproofing.
Flood Testing is performed on new low-slope horizontal waterproofing installations such as parking garages and plaza decks. As part of a leak investigation, flood testing is performed on low-slope building roofs. Containment assemblies are sometimes constructed around the horizontal regions to be tested.
Deluge Testing is performed on new exterior windows, skylights, doors, and curtain walls. As part of a leak investigation, a modified version of deluge testing is used on masonry walls. Calibrated spray racks capable of delivering water uniformly at a minimum rate of 3.4 liter per square meter per minute are used. For new installations or manufactured samples, a pressure chamber is also attached and a static or cyclic air pressure differential maintained throughout the test.
Leakage Mapping is performed on new storefronts, curtain walls, and sloped glazing systems. As part of a leak investigation, leakage mapping can be performed on window joints and other suspect frames. A special nozzle and 30 to 35 psi of dynamic water pressure are applied one foot from each 5 foot joint for 5 minutes.
With new construction, verification is achieved if no water leaks into the interior. With leak investigations, where there may be signs of interior water damage but no actual leaks, infrared (IR) thermography and electrical capacitance (EC) testing are used in addition to visual inspection to determine whether water penetration is occurring.
Water pressure and flow rate
Available on-site water pressure will be a factor in testing. Static water pressure is the pressure when no water is flowing. This can be high; unfortunately, it is irrelevant. What is important is the dynamic water pressure, the pressure at the end of the water testing device when water is flowing.
Dynamic water pressure is affected by many factors:
- Dynamic (as opposed to static) water pressure at the source
- Length of hose from the source
- Height of test device from the source
- Flow rate through the test device
Leakage Mapping requires the highest flow rate. Depending upon the area to be covered, Deluge Testing typically requires a low flow rate. For Flood Testing, the flow rate available will determine the time to fill the test area to the required height.
When there is insufficient dynamic water pressure at the testing device, a pump may be needed.
Although Water Testing may appear to be the simplest of the NDT techniques to perform, NDT test agencies must be prepared to handle all contingencies in configuration on-site.
- Calibrated spray racks with adjustable stand-offs
- Leakage Mapping nozzle
- Pressure gauges
- Pump and extension cords
- IR camera
- EC meter
- Portable weather station (temperature, relative humidity, wind speed)
- On/Off valves
- Y-connectors (hose splitters)
- Drain plugs and Bucket with holes for controlled release
- Ruler and pan
- Wood, Sandbags, and Waterproofing for containment assembly
- Waterproof ropes
- Weights and/or C-clamps
- Spare washers and Sealing tape (for proper seals at hose ends)
This is in contrast to most other forms of NDT testing, where, aside from issues of access, a single NDT Technician and one piece of specialized equipment is typically needed.