Advice on Porter Vacuum Block


22nd September 2015


The porter brown Vacuum Control block is a multi-application item. It can be used in three different ways:

· Connection to an AGS Adapter fit to an Anaesthetic Gas Scavenging System Terminal

· Connection to a High Volume Port on Dental Chair Suction

· Connection to a MiniScav

The first two items have a high suction and in these cases, the VCB is required to reduce the draw on the attached breathing system to the recommended working level of around 45 L/min. This is to prevent fresh gases being ‘sucked’ out of the system when the patient exhales and the inner liner flapper valve opens.

The Miniscav is different. These units, which are essentially a cased pump, are factory set at a draw level of 46 L/min – and in this case, the VCB is therefore only used as solid connection between the breathing system and Miniscav inlet. The black bobbin will not lift or adjust, but merely ‘quiver’ in the base of the channel. This, taken into conjunction with the quiet ‘hiss’ that can be heard at the nasal mask is the indication that everything is operating correctly.

This does mean that regular, documented maintenance on the MiniScav is vital, to ensure it is operating at the correct draw. The current service protocol for a MiniScav unit is:

Year 1 – service check on customer site.

Year 2 – service exchange of unit. This consists of a workshop serviced unit brought along by the engineer attending and ‘swopped’ for the existing 2 year old unit. The maintenance programme allows for repairs, service and upgrades that would not be able to be accomplished in the field.

It is important to understand that a VCB will operate differently when connected to a MiniScav. If you have any further queries with regard to operation please email:

RA Medical Services Ltd