Feature or there is a push of the limits in terms of high-pressure to lowpressure then obviously that may alter things .”
Regarding the trend to digitise gauges , Reinach notes that such a gauge only gives the pressure reading , not the equivalent in temperature – whereas analogue gauges give the pressure and temperature equivalents already printed on the scale . This may mean that with digital there would be the inconvenience of having to switch between screens to see both readings . In addition , he says , “[ A ] t the moment digital is too expensive .”
“ Pipes and valves generally are purchased as a set , with the choice of a gauge being determined by the consulting engineers based on what they want from the system and whether or not they even want a gauge on the system . You do not necessarily have to have a gauge – if the engineer is confident in the pump one can get away without having a gauge and can rather just have sensors on it . However , the majority of cases do have at least one gauge . One can also get away with using a gauge only in the commissioning phase and thereafter remove it and occasionally return it for a check-up every now and again .
“ When it comes to choice of system , the technician or engineer would specify what they ' re looking for , such as a certain amount of pressure or temperature : it is this criteria for pressure and temperature that dictates the choice of gauge . A refrigeration gauge is actually a pressure gauge with a temperature scale on , because the amount of pressure on a certain gas is equal to X-amount of temperature for the gas . If you pressurise gas to say 10 bar it could be equal to 10 degrees Celsius on R410A gas ,” says Reinach .
End users don ’ t get involved in servicing gauges , he notes , they would have to send it for calibration to test it is still within its accuracy class . If they require a calibration certificate , which is becoming the norm these days , “[ W ] e would issue one to international standards ”, he says .
“ On the digital side there ' s a lot of R & D happening – but for analogue there ' s really no R & D taking place anymore because the product has been in the market for 100 plus years and it works on the same principles . Not much is changing other than perhaps trying out new materials other than copper beryllium , brass and stainless-steel tubes . A lot of the old school guys still prefer having analogue to digital because with analogue they can see
WIKA website WIKA website
it working , while with digital they ' re less certain – it just gives a digital reading which could be frozen .
“ The selection of raw material for the gauge depends on the media or liquids getting pumped through the system , determining whether to go to a stainless-steel gauge rather than brass or copper .”
BRINGING IT ALL TOGETHER : PIPES , VALVES , GAUGES AND THE IOT IoT gives companies opportunities to intelligently monitor and
control the performance and condition of HVAC systems 2 . There are the five primary ways companies use IoT to improve operations :
• Preventative maintenance
• Energy efficiency
• Remote system monitoring and control
• Regulatory compliance
• Regular servicing plans
Bourdon tube pressure gauge with switch contacts .
High-quality pressure sensor with mounted diaphragm seal .
“ There are currently probably 20 or 30 different types of configurations , and I expect this to standardise down to between four and six gauges .”
Whereas for a long time , ‘ physical-based ’ techniques were the driving force for the industry when optimising , modelling and maintaining HVAC systems , lately this is now veering towards data-driven approaches instead . Lloyd Townsend , product manager at WIKA , explains : “ A data-driven approach is only as good as its data , of course , but as communication and information technology have continued to evolve , data has become more accessible , allowing HVAC companies to now collect and disseminate more data at once .”
www . refrigerationandaircon . co . za RACA Journal I April 2023 31