Dental Surgery N2O Leak Detected

A dental engineer rapidly detected a leak in sedation equipment at a dental surgery in Dover (UK) when sent to investigate N2O problems after staff complaints about gas effects. Using a Geotech (UK) G200 N2O monitor supplied by Bedfont Scientific, the engineer was able to identify that the leak came from faulty sedation equipment. In addition he used two other G200s to monitor the time-weighted average (TWA) of two members of staff.

Previous passive monitoring in the surgery had indicated a TWA of N2O at 90ppm, and because of a suspected leak in a faulty machine it was sent for service and repair to fix the problem. However, staff continued to notice the effects of N2O.

The engineer sent to investigate said, "I had three G200 monitors and set one up to monitor the area around the machine and then asked the dentist and nurse to wear one each on 'person mode'. We monitored for two and a half hours over the morning session and did two treatments in that period using that particular machine. At lunchtime I checked the readings and the area monitor was sitting at 220ppm average, the dentist's personal monitor was showing a TWA of 105ppm and the nurse's was at 67ppm. These readings were pretty high for such a short period so I set the area monitor onto 'leak mode' and used it to "sniff" around the machine with it set to deliver 20% N2O at a low flow rate with the scavenger and delivery circuit connected. I found that the air intake of the mixer head on the machine was spewing out N2O at an alarming rate - the readings went up to over 4,000ppm."

The engineer reported the findings to the sedation equipment supplier who confirmed that a valve inside was most likely faulty and they would issue a replacement.

The engineer added, "Once the replacement is fitted we will repeat the monitoring to ensure it is working correctly."

The surgery now has its own G200 monitor so the staff can easily keep a check on their equipment and they are planning to roll out a monitoring program to cover all of their sites.

The Geotech G200 is designed to monitor background and breathing-zone levels of N2O in medical environments. It can measure N2O at 0-1,000ppm and can calculate time weighted averages, as well as EH40 occupational exposure limits. It is also highly effective in detecting N2O leaks.