Folding rule, spirit level and pencil are still the faithful companions of many craftsmen. Digital professional measuring instruments can make their work much easier. Digital measuring instruments convince by their accuracy and offer additionally high comfort in the operation as well as valuable additional functions.
In this guide, we present some frequently used measuring instruments for recording distances or for levelling. In addition, we also discuss less common measuring instruments such as those used to measure brightness, noise or temperature.
Laser rangefinder
The classic folding rule brings with it blatant inaccuracies – especially when the distance is greater than the folding rule length. In addition, spaces can accidentally be measured at an angle. It becomes particularly difficult if there is an obstacle in the measuring path. This is no longer a problem with laser rangefinders. After activation, the red laser dot is visible as a target aid. The distance is measured by measuring the transit time of the pulsed laser light reflected at the measuring point.Depending on individual requirements, good devices can achieve a measuring distance of 30 to 100 meters in daylight and offer a deviation of only two millimeters even at longer distances.
If you want to measure the distance between two walls, you should activate a continuous measurement to read the minimum value on the display, which should be as multiline as possible. Conversely, a corner of a room can be measured by reading the maximum value. If the height of a wall with an obstacle is to be measured, an indirect measurement using the integrated angle/tilt meter is very practical – here, depending on the measurement mode, you aim diagonally upwards and/or downwards and horizontally – the height is then automatically calculated according to the Pythagorean theorem. Vice versa, the intermediate angle can be displayed by two measurements towards the wall and diagonally upwards.
Intermediate storage of measured values and integrated calculation functions are also practical. For example, wall surfaces can be measured to estimate the required paint, or room volumes for the dimensioning of a fan. With good laser distance meters, the reference point for distance measurement can be switched: for example, between the front or rear edge of the device or the center point when operating on a tripod.
Cross line laser
Horizontal auxiliary lines are an indispensable must not only on building sites – for levelling the floor as well as for tiling. Line lasers also prove to be practical helpers when hanging several pictures in a room. Thanks to special optics, they do not emit the light of the laser as a point of light, but rather expand it to form a thin line. With simple line lasers, however, this line must be aligned manually or using a spirit level.More comfortable line lasers are self-levelling, but must be roughly levelled on the tripod using a spirit level, because the automatic levelling system only compensates for small inclinations up to about +/- 4°.
For the exact positioning of objects in a room, the use of a cross line laser is very useful, because in addition to the horizontal line, it also projects an absolutely vertical line on the wall. Good entry-level cross line lasers have a range of 20 meters and a levelling accuracy of +- 3 millimeters at a distance of 10 meters. In addition, such devices offer a beam angle of at least 100 degrees. The length of the levelling lines that can be realized in this way is slightly more than one and a half times the distance at a 100 degree angle of inclination – so at a laser wall distance of three meters, the cross lines have a length of more than 4.50 meters.
Luxmeter
Anyone wishing to measure illuminance, for example to comply with occupational health and safety and sports facility regulations or to check the local brightness of streetlights, uses a luxmeter for this purpose. Good luxmeters are suitable for outdoor use and can also be used at temperatures below zero and in direct sunlight. They consist of a central unit with display and a light sensor that can be used separately. In this way, they can be flexibly adapted to the application or quickly used for manual measurement.It is important that a luxmeter can compensate for the spectral errors of light sources, because fluorescent lamps or LED lights, for example, are perceived very differently by the human eye depending on their color temperature. If the luxmeter is suitable for long-term recording as a data logger, the measured light values can be conveniently read out on a PC and processed optically or in tabular form. Data is transferred to the PC via a USB data cable or via Bluetooth®. For the systematic recording of rooms, it would also make sense for the luxmeter to enable the cartographic recording of rooms using a MAP function.
Sound level meter
Sound level meters are also useful at municipal level or for checking occupational health and safety regulations. For quantitatively verifiable measurements, one will not be able to avoid purchasing a device suitable for outdoor use with calibration capability, but an initial orientation about locally existing noise levels is already possible in the price range below 50 euros. The basic prerequisite for this is that the measuring microphone has a wind-proof protective ball at its tip and can measure cyclically at one-second intervals or at even shorter intervals.For a first qualitative impression, the device should record measurements from a level of about 30 dBA. It would also be useful if the display showed the minimum and maximum noise levels in dBA. In addition, a USB interface or Bluetooth® should be available as data interface. An app for visualizing and archiving the measured values on a smartphone is also a useful additional function. However, entry-level devices only have a limited measurement accuracy in the range of approx. +/- 1.5 dB.
In the next price class there is an integrated data logger and the measurement accuracy increases to +/- 0.1 dB. However, the acoustic measurements only become really meaningful in combination with an integrated analyzer function for recording and visualizing the frequency response of the measured background noise.
Thermal imaging camera
Another specialty for local measurements are thermal imaging cameras, which are also available in all conceivable price ranges. A distinction is made between the most diverse areas of application and temperature ranges. For example, there are systems that detect very low temperatures with high resolution and display them on the color display in a wide range of colors – from blue for low temperatures, through violet and red for medium temperatures, to yellow and white for high temperatures. These cameras can be used in building thermography, for example, to detect cold bridges and leaks in the building shell or to locate people and animals at night. At the upper end of the temperature scale, there are cameras that fire brigades, for example, use to locate high-temperature hot spots after a fire.The large price difference of thermal imaging cameras is mainly based on the sensor technology and the respective optical resolution of these cameras. Entry level pocket devices work with an infrared image sensor and a typical resolution of, for example, 80 x 60 measuring points. Professional thermal imaging cameras today have an infrared resolution of 640 x 480 pixels as well as a special highly sensitive radiation sensor (bolometer) and also have an additional high-resolution digital camera for overlapping the recorded thermal image with a detailed representation of the real building envelope.
Conclusion: the right device for every purpose
Digital laser measuring instruments and laser levelling instruments are far superior to analogue measuring methods, even in the entry-level price class. More professional versions often offer valuable additional functions for data storage and analysis. Whether it is frequently occurring measurements such as distance measurements, less frequently occurring measurements such as noise level measurements or special applications such as testing insulation with a thermal imaging camera: Professionals and DIYers alike will find the right instrument for their requirements and field of application.
