Multifunction transmitters are multi-parameter transducers providing the full range of measurement capabilities needed to manage the various parameters of a building’s indoor air. These stationary measuring instruments are designed for use in the most critical and sensitive controlled-atmosphere environments. These environments require flawless air quality management. They can be found in laboratories, clean rooms and other types of high-tech facilities (such as medical store rooms and electronics production lines). 

State-of-the-art transducers required for regulated environments 

Sauermann transmitters are state-of-the-art fixed measurement instruments offering market-leading accuracy and robust, long-term measurement stability. These instruments are designed, calibrated and certified to set the gold standard for reliability, giving professionals certainty that their critical facilities and regulated environments comply with the necessary requirements. 

In the world of ventilation, multi-parameter transmitters are used to monitor all indoor air parameters in a controlled-atmosphere environment: 

  • Pressure and differential pressure for air filters, and positive or negative pressure cascades to isolate different areas of a building via over-pressure and/or under-pressure 
  • Air temperature 
  • Hygrometry (relative humidity) 
  • Air velocity 
  • Air flow in a duct, or at a ventilation inlet or outlet (to control over-pressure and under-pressure cascades) 
  • Concentrations of carbon monoxide (CO), carbon dioxide (CO2) and volatile organic compounds (VOCs) 

Although these measurement instruments are fixed, they can accommodate field-replaceable probes, allowing different air parameters to be measured within an HVACR monitoring network. 

Converters designed for maximum durability 

Multifunction transmitters convert all types of air parameters into analogue or digital signals. They must be designed to withstand their operating environment, since any disruption to the electronic conversion process can affect measurement accuracy, which is essential for ensuring that premises with a strictly regulated indoor environment remain compliant with requirements. 

This is why a transmitter needs to operate flawlessly over a wide range of ambient temperature and humidity values, while providing a high degree of ingress protection (IP65 or even IP66). The casing must also be resistant to vaporised hydrogen peroxide (VHP), a cleaning product widely used in sterile environments, clean rooms and laboratories, where contamination must be avoided at all costs. 

State-of-the-art fixed multi-parameter transducers undergo a calibration procedure to ensure that their measurement accuracy remains highly stable over a long period of operation. To this end, they must be fitted with a differential pressure sensor with a solenoid-operated auto-calibration (auto-zero) system, in order maintain pressure measurement capability without zero-point drift (known as “measurement repeatability”). The frequency of this automatic calibration procedure is user-programmable. 

In order to compensate for the extreme sensitivity of this type of pressure sensor, Sauermann pressure transmitters are equipped with a measurement smoothing system. The intensity of this system can be configured in order adapt to unstable atmospheres, thereby providing a stable measurement that’s more reliable over time. 

Regular instrument calibration (approximately once a year) nevertheless remains a universal rule in metrology, not least because it’s an integral part of the repeatability and compliance requirements that apply to regulated environments. 

Fixed, connected measurement instruments for EMS and BMS 

These transmitters are also called converters because they convert the measurements captured by the probes and sensors into electrical signals, which are then transmitted via an analogue or digital circuit. The measurements can be converted into volts (over voltage ranges of 0–5 V or 0–10 V) or into amperes (over current ranges of 0–20 mA or 4–20 mA). 

These converted signals carry measurements over a long-range wired communication network within a building. This network is built around a centralised Building Management System (BMS) or EMS (Environmental Monitoring System). As well as transmitting their own measurements, fixed transducers can also relay measurements from other devices. This can be done by configuring certain communication channels on the instrument as relays. 

The very latest transmitters also include a wireless connection module (sometimes optional) for smartphones, tablets and laptops. Using a dedicated Android, Windows or iOS app, the user can then control and configure the measurement instrument and probes, update the firmware, and even retrieve and export the measurements stored in the instrument’s internal memory. 
 
Fixed measurement instruments with integrated display and controls, and visual and audible alarms 

Since transmitters are fixed measurement instruments, it must be possible for users to configure them in situ, and for metrology engineers to calibrate them on site (a service that Sauermann also offers). The fixed instrument therefore needs to include an integrated display, with touch or button control, so it can be configured without needing to be removed. 

One aspect that can be configured on site is the transducer’s audible and visual alarm systems, which provide a direct warning to occupants on site, as well as relaying alarms via the building’s computerised management system (EMS and/or BMS).