Optimised measuring chains increase the efficiency of working procedures
Precise room and building climate measurements are challenging and require the compilation, analysis and documentation of a wide range of parameters. Thus, instruments which support the efficient processing and management of relevant data make the work of plant constructors, experts, consultants or service providers in the field of ventilation and air conditioning considerably easier. The following article illustrates the possibilities resulting from the current state of the art.
The range of technical instruments available on the market for
measuring room climate reflects the wide range of requirements in this field. Depending on the intended application, different accuracy tolerances and features are of significance. However, anyone who regularly uses
measuring instruments as part of his/her professional activities should not only be concerned about the required or prescribed measuring accuracy. In day-to-day work, aspects such as convenience of use, the capabilities for efficient further processing of the measurement data or the robustness of the technology under building site conditions are also of crucial importance.
Entry-level instruments for standard tasks
Making a decision as to which instrument to purchase for simple measuring tasks is relatively easy. Here are a few practical examples: An HVAC expert wishes to check the insulation work on a heating system using
non-contact temperature measurement. Or he is scanning the walls for the coldest points, in order to make the house owner aware of the mould problem. The common factor in such applications is that the measuring accuracy required is regarded as rather average. Moreover, there is no need to spend a lot of time and effort preparing documentation, which is an essential component of more demanding measuring tasks. Here entry-level instruments are normally sufficient for the controlled ventilation of living spaces, for example, and are available within the correspondingly low price brackets.
Climate measurement technology for complex requirements
More stringent demands are placed on professional climate analysis instruments. Various measurement parameters need to be determined, sometimes under extremely variable conditions. For the flow velocity there are
measuring probes specifically for ventilation ducts, outlets and for checking comfort level conditions in the workplace. Add to this temperature, humidity, pressure and also
CO2 concentration measurements. These measuring tasks are not only carried out when installing and commissioning ventilation and air conditioning systems, they are also required during regular maintenance and inspections. Moreover, there is a wide range of analyses intended to rectify any lack of comfort, whether it be draughts, uncomfortable temperatures or tiredness as a result of high CO2 concentrations. Sometimes extremely complex measurements are required here, and these may extend over periods of several hours or days and include the evaluation of all climatic values acting upon the individuals concerned. Both newcomers to the industry and experts merely looking to brush up their knowledge can acquire the appropriate expertise and learn how to apply it in practice, through training sessions and seminars, such as those offered by Testo AG from Lenzkirch – a leading manufacturer of portable and stationary measuring technology.
Numerous standards are applied when carrying out the measurements, such as ensuring that the degrees of turbulence are determined at ankle, chest and head height for optimum analysis of the draught effect on a person in the room. Huge amounts of data are always recorded and processed in climate measurements of this kind, in order, among other things, to be able to recognise temporary disruptions – such as the opening of doors or windows – in the data records and take them into account accordingly. There are also standards for measurements in ventilation channels which, for example, prescribe a mean calculation for the flow profile. Consequently, these kinds of measuring tasks are usually carried out by highly-qualified specialists such as skilled tradesmen, technicians, engineers and experts. Although most standards are advisory only, a growing number of customers deem it important for measurements to be standards-compliant, and this entails spending more time and effort on documentation. Therefore, greater convenience in using measuring instruments and efficient work processes are just as important to users as having the capabilities for efficient further processing and for managing huge amounts of data.
Advantages of digital probe technology
One development which brings considerable advantages with it, in particular for demanding measuring tasks in air conditioning and ventilation systems, is digital probe technology. Up to now, analogue measuring signals have been transmitted from the probes to the evaluation unit – that is, the handheld instrument – and converted into digital signals there for further processing. This signal processing, however, is subject to system-related uncertainties, the cause of which is mostly to be found in the interface between the handheld instrument and the probe. In digital technology, the probe itself produces a digital value, which is transmitted to the measuring instrument with no loss of information and totally error-free. The metrological intelligence is within the actual probe, while the handheld instrument serves as a display unit with different functions for saving and processing the data.
A further advantage of this technology is the fact that the user only needs to send the relevant probe into the calibration laboratory for the calibration that is required periodically; there is no longer any need to send in the complete system. Meanwhile the other probes can continue to be used with the handheld instrument.
Workflow optimisation measures
In addition to the digital probe technology, modern measuring instruments – such as the newly developed
VAC measuring instrument testo 480 – also have further innovative features for a high degree of user convenience and to efficiently evaluate, process and manage large amounts of data. Instead of navigating through the menus with cursor keys, here a so-called trackpad – similar to those found in Notebooks – facilitates the input by means of a touch-sensitive sensor surface. At the same time the multiple function of keys has been done away with, making operation of the handheld instrument much faster, simpler and more efficient.
Guided programs, which for example guarantee standards-compliant grid measurement on a VAC system in accordance with EN 12599, support the measuring process itself. There is also the option of configuring the reading display individually, thus creating a display and evaluation tailored to personal preferences. Archives, similar in structure to Windows Explorer, can be built up in the handheld instrument, enabling measurement data to be assigned to individual customers simply and directly. The colour display tops off the instrument's equipment, guaranteeing a high degree of user convenience.
The software shipped with the measuring instrument should also make data management and processing much simpler. Ideally, the complete data tree can be transmitted from the handheld instrument to the PC for further processing. Subsequently, professional protocols can be created on the computer based on previously stored templates. Here measuring locations, date, time, the recorded values, and if necessary also the logo of the service provider can be integrated quickly and easily. The possibility of transmitting data via a USB connection as well as by means of an SD card guarantees a high degree of flexibility. Thus, the air conditioning engineer can, for example, give the measurement results to a colleague to evaluate in the office and keep another appointment himself. Instrument and measurement data may therefore be used independently of one another.
Decision-making criteria for professional VAC measuring instruments
Finally, the above instrument features collectively contribute to optimising the entire measurement chain, which ranges from preparing the measurement to recording the measurement parameters, and extends right up to creating the protocol. Most notably, the evaluations can be carried out using innovative measuring technology in a way that saves both time and money. This increases the efficiency of working procedures for all users, whether we're talking about a plant constructor, someone who provides air conditioning systems maintenance, an expert or consultant, or even an employee in the Facility Management Department of an industrial company or someone who runs an office block.
Thus, it is quite clear that solely comparing prices and measuring accuracies is not sufficient to select a professional VAC measuring instrument. In fact, the organisational support and the software provided ought also be put to the test. An ideal scenario is where the measurement data can be managed efficiently and recorded in compliance with the standards. The results must be able to be evaluated and configured individually to customer requirements. In this context efficiency means added value, because ultimately the customer is paying for the measurement protocol.
Info boxes:
Standards relevant to air conditioning measurement technology
VDI 2083-3 Clean room technology
VDI 6022 Hygiene requirements for VAC systems
EN 12599 Test procedures and measurement methods for handing over ventilation and air conditioning systems
EN 13779 Basic principles for planning, construction and operation for ventilation in non-residential buildings
ISO 7726 Ambient climate, instruments and methods for measurement
ISO 7243 Climate measurements at the workplace in the industrial sector
ISO 7730 Method for predicting human thermal sensation
DIN 18017 Ventilation of bathrooms and toilets, external windows with fans (Part 3)
DIN 33403-3 Climate at the workplace
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Precise room and building climate measurements are challenging and require various measurement parameters to be established, sometimes under extremely variable conditions.
In the case of comfort level measurement at the workplace, temperature and flow velocity, and hence the degree of turbulence, are measured at ankle, chest and head height over a prolonged period of time, in order to be able to analyse the draught effect on a person in the room.
Digital probe technology transfers the measured values to the handheld instrument securely and reliably, guarantees a zero-error display thanks to the automatic elimination of deviations, and automatically sends notification when the next calibration is due to be carried out.
In digital probe technology there is no longer any need to send in the complete system for the calibration, just the relevant probe. Meanwhile the other probes can continue to be used with the handheld instrument.
In the case of
modern measuring instruments such as the testo 480, the so-called trackpad, a clear archive structure which can be individually configured, and a colour display, among other things, all ensure a high degree of user convenience.
The software shipped with the measuring instrument should enable measurement protocols to be created quickly and easily, and to be configured in a manner that is tailored to the customer. The possibility of transmitting data via a USB connection as well as by means of an SD card also guarantees a high degree of flexibility.
