Problems with high‐flow Scavenging systems

1 -30 mm An active scavenging system (British Oxygen Company) has recently been installed in our hospital. Each terminal has a flow capacity of IM) f 10 litresi min: the 1980 Draft British Standard flow is specified as a composite wave form peaking at I30 litresimin. Since the hissing noise of the high extraction flow rate annoyed some theatre users and patients. our Occupational Health Service measured the noise levels. shown in Table I .