Ethylene Oxide System for Safe Working in Sterile Environment

Jan 30, 2018

Ethylene Oxide System for Safe Working in Sterile Environment

by | Jan 30, 2018


a1-cbiss is a gas detection solution providing company specialising in bespoke design of fixed gas detection systems. We are always looking to assist our clients with their specific gas detection and monitoring needs. A recent solution that we have designed is for the measurement of Ethylene Oxide (EO/ETO) at very low levels.

Given its versatility, ETO is most widely used as a sterilant. In the sterilisation industry, the Occupational Hygiene Exposure Standards require EO/ETO to be measured extremely accurately at low levels to ensure personal safety and legal standards are met. Monitoring the breathing environment near sterilisation equipment is essential because of the number of potential health risks that ethylene oxide poses.

Dangers of ETO Exposure

Whilst ETO has the properties for an excellent sterilant, unfortunately, exposure to ETO gas can cause detrimental health effects. The prime factor in installing this ETO monitoring system was a result of complaints from personnel who are subject to breathing ethylene oxide. These people are complaining of headaches, nausea, vomiting, diarrhea, and shortness of breath.

Depending on the levels that are monitored, this will determine the action that is to be taken by the client and the personnel involved in their process. This will include, but is not limited to, the activation of additional ventilation, donning of respiratory protection equipment or breathing apparatus. EO/ETO legal limits are governed differently depending on the country of operation.

In consultation with an independent occupational hygienist, the target gas levels could be set as follows:

  • Green / Safe < 0.5 ppm (normal operations)
  • Amber / 1st action level ≥ 0.5 ppm (site dependant)
  • Red / 2nd action level ≥ 3.5 ppm (site dependant)

Each site will differ in how they mitigate the contact of the personnel with the target gas.


a1-cbiss were contacted to assist a client in the Czech Republic who had an existing electrochemical EO/ETO monitoring system on site. The client is required to meet legal requirements to ensure personal safety and legal standards were met, however, their current system did not meet any of the operational nor legal requirements.

The problem with Ethylene Oxide gas detectors is that they generally use electrochemical sensors. These potentially have the tendency to respond to a wide range of other gases. This could lead to inaccurate results and false alarms.

a1-cbiss have been designing bespoke gas detection systems for over 25 years so the client was confident that a1-cbiss would deliver a successful project. Both the engineering and technical sales teams from a1-cbiss have many years of combined expertise and knowledge from numerous gas detection applications.

a1-cbiss hosted the initial meetings to determine the client’s exact requirements:

  • Meet operational and legal requirements
  • Multiple monitoring points
  • Traffic light warning system
  • LEL detection in some areas
  • Data logging and reporting
  • Reliable technology
  • Easy to operate
  • Ease of servicing
  • Installation in Czech Republic 


A design review was held by a1-cbiss to design the system.

After several consultative meetings, a1-cbiss developed the design:

  • Photoacoustic analyser from Innova – an a1-cbiss partner. This form of gas detection provides very accurate and reliable data and can provide ppb to ppm measurements
  • CDAS – An a1-cbiss data collection and reporting software. As this is an in-house product, it can be adapted for specific applications with reduced costs (not 3rd party software)
  • a1-cbiss 32 channel multiplexor sampling system
  • CDAS driven traffic light warning system with specific time delay functions included
  • Oldham MX43 gas controller with LEL detectors integrated into the data logging software
  • The reliability of the Innova analyser is the leader in class for this type of detection
  • Photoacoustic detection of gases has been used very successfully and reliably for many years in many different applications.
  • This analyser was selected for these reasons and its ease of use
  • Traffic light system to communicate gas levels or warn personnel of potential dangers

An initial cost and time-scale were put together and then presented to the client. Costs were subject to change on the completion of a site visit and occupational hygiene survey. The initial cost was approved and the design and build progressed.

What is a Sampling System?

The a1-cbiss Intelligent Sampling System is a single board computer-controlled industrial sequencer.

The intelligent sampler, when connected to a suitable gas analyser(s) or point sensor(s) forms a multi-point area monitoring system that can monitor a wide area by sequentially drawing gas to the analyser(s) and reading the concentration. The a1-cbiss sampler has an alarm and reporting software developed over many years.

The unit can take data from up to 6 gas analysers/sensors via analogue, comms, Ethernet and many software drivers have been written.


a1-cbiss sent an experienced installation team to complete some pre-installation work including the occupational hygiene survey and full site visit. During the site visit in the Czech Republic, some additional operational requirements were necessary. These additional requirements were easily added to the original design and costed for.

The install of the EO/ETO system was to be completed in two stages. Whilst the system was being built at a1-cbiss premises in the UK, an installation team travelled to site to install all the ancillary equipment. This included all the necessary sample tubing, cabling and traffic light warning systems.

Once the system build was complete, the same installation team returned to site to complete the full installation of the EO/ETO monitoring system. This included the main components of the system and the data collection software.



Upon completion of the full system, thorough testing and commissioning were carried out to ensure the integrity of the system and give the client confidence and 100% piece of mind of a correctly working system.

A Czech Republic Ministry of Health site visit was completed soon after the installation. The site was commended on the system and operation thereof.

The result was a happy client. This has led to a further agreement with the client for a1-cbiss to supply all of the existing sites within the UK and Europe.


To find out more about how you can help keep workers safe from Ethylene Oxide within the sterilisation process, contact a1-cbiss