This follow-up to a previous article on the importance of field verification, testing responsibilities, and reporting protocol describes some of the equipment and instruments this author frequently uses when visiting construction sites. (For the first part of this article, see the author’s “Trust, but Verify: Tools and Tricks for the Design Professional” in the February 2012 issue of The Construction Specifier.)
Testing can normally be divided into two categories—nondestructive (NDT), which does not harm or damage the entity or require its removal, and destructive (in which case the subject is altered or removed from the location and repair is later required). Regardless of which of these two paths is chosen, it is usually best that the test equipment is used and maintained by the same person. This ensures the equipment’s condition is always known after each use, and it is operated properly, with clear maintenance and calibration history.
Further, when the same person uses the equipment, he or she gains valuable experience and treats the devices in the same manner. When multiple individuals use the same equipment, accidents or neglect is more probable, and problems may not be communicated to others.
Some equipment does not require batteries, some equipment uses rechargeable ones, and others employ disposable. This author feels more comfortable with the latter because the charge seems to last longer. It is very easy to grab the needed spares as opposed to maintaining a whole wall of electrical outlets to accommodate the different rechargeable batteries and their rechargers.
Choose your weapons
When selecting test equipment, it is usually advantageous and more economical to avoid entry-level equipment. One should check capabilities and features and compare to ultimate needs. Initially, entry-level equipment may be easier to learn than advanced equipment, but these devices may quickly become inadequate and no longer meet needs. As experience is gained, there may be an impulse to upgrade equipment. Thus, it would be prudent to purchase one’s ‘second’ instrument first. Upgrading can be expensive and can leave a person with a drawer full of unused gadgets and black boxes.
The display is a vital part of the usefulness of the meter. Although a digital display can provide readings more precisely than a pointer, unless the screen is non-glare or has high contrasting readings and background (or is backlit), the information can be difficult to read, especially when viewed in bright light or at an angle. Some instruments have a lit background, but this usually offers little improvement. Usually, a needle display is much easier to read thana digital display under varying light conditions, but precision in reading may be sacrificed with a needle display.
The following list of diagnostic tools is neither all-inclusive nor overly detailed. Instead, it represents selected items from the author’s toolbox repertoire of useful equipment. When choosing tools, one should consider those with which he or she is familiar and complements his or her specialty. For instance, a structural engineer may not need a moisture meter or sound meter, but a metal scanner, dry film gauge, or inclinometer would be useful.
This device measures surface temperature without contacting the surface. It should have a minimum distance ratio of 12:1 and a temperature range of –18 to 370 C (0 to 700 F), and be able to quickly determine whether asphalt is too hot or cold, if surfaces are too hot or cold to paint, or if surfaces are approaching dewpoint.
Air monitors show ambient temperature, relative humidity, dewpoint, and wind speed. They are used to determine suitable conditions for painting, interior casework installation, and other tasks. (Wind speed should also have an fpm scale to measure HVAC airflow.)
The sling psychrometer tool very accurately measures ambient wet bulb and dry bulb temperature for conversion to relative humidity and dewpoints using integral scales.