Protea Limited

Measurement solutions for hospital workplace exposure monitoring - Monitoring and Testing

In taking a responsible stance on the exposure of workers to any potentially hazardous gases, there is a need for workplaces using anaesthetic gases, such as hospital operating rooms or research laboratories, to control the level of waste anaesthetic gas in the ambient air

Anaesthesia machines, ventilators, breathing systems and waste gas scavenging systems will all contribute to the background level of the anaesthetic gases that are present in the environment within a facility, whether those machines are in a good state of repair or not. Recovery rooms can become polluted, for example from gas exhaled by the patient, and clean-up from any spills can remain in the background air for long periods.

Waste gas disposal can be carried out with a well-functioning non-circulating room ventilation system. However, the monitoring of trace gas levels of anaesthetic gases in this workplace allows building management systems to assess and control the waste gas control system and provide workers with a safe and healthy working environment plus that all important confidence that all is well.

atmosFIR Solution

Protea’s latest FTIR multigas analyser, atmosFIR, uses full spectrum infrared analysis and is able to measure all anaesthetic gases simultaneously. The analyser is a high resolution and compact analyser module with a room temperature operated DTGS detector that is ideally suited to measuring all the halogenated and other compounds present such as Halothane, Isoflurane, Sevoflurane and Desflurane.

Multigas speciation

The key to this product is the combination of a new generation FTIR with Protea’s advanced chemometric algorithm within the FTIR software which separates and quantifies each gas response individually and accurately (see Figure 1). Protea’s analysis method is real-time, seamless and provides specific gas concentrations on screen, with configurable alarms to give appropriate status levels or warnings. The system is also able to indicate that individual concentrations are being measured correctly and conversely if there is a problem.

With an internal measurement cell optimised for workplace exposure limit measurements of anaesthetic gases, the system has a low level of detection. Figure 2 gives common gas species ranges, detection limits and comparison with exposure limits.

Multi-stream measurement

The atmosFIR system for workplace exposure monitoring is not limited to a single point of measurement. By incorporating a multi-stream switching system, the analyser can be programmed to sample across a number of different measurement points in a sequence. For example, it can measure at a number of locations within an operating theatre –such as the gas delivery equipment and at the location of waste gas removal. The controlling programme can be sequenced to allow some measurement points to be sampled for longer or shorter than others. By using easy to install PTFE sample lines and a suitable sample flow rate, each measurement point can generate an accurate result in 30 seconds or less.

Data output and Management System interface

atmosFIR allows data to be outputted by a number of alternative routes. For direct interface with the Building Management System (BMS) for control of air circulation, analogue and digital data outputs are available over 4-20mA or Modbus protocols. All gas readings are saved locally into dedicated data files for each measurement point. OPC data exchange can be used to output data into a database or spreadsheet in real-time. A digital alarm signal can be programmed to give a simple alarm output (numerical or warning lights) should any gas species go above a caution or danger level.

Multi-purpose expandable analysis

The benefit of the atmosFIR FTIR analyser is that it can be programmed for hundreds of different gas mixtures. With Protea’s customised chemometrics analysis files, the analyser can be programmed to measure completely different gases and is even able to measure different gases at each individual measurement point if required. So atmosFIR can extend measurement to cover more workplace gases or be reconfigured if there are any changes in anaesthetics or substances in use. Exposure from the gases list in Figure 3 can be expected from releases in a hospital or medical environment hospital and the atmosFIR systems provides real-time monitoring of these species in addition to the anaesthetic gases with no need for hardware changes.