Assessment of air ingress to steam systems

Apparatus for assessing the ingress of air into a steam system which comprises at least a steam condenser having an exit, a vacuum pump arrangement for maintaining the exit under a partial vacuum, and pipework connecting the exit to the vacuum pump arrangement, the apparatus comprising a pitot probe positioned at a first monitoring point in said pipework past which the flow from the condenser to said vacuum pump arrangement passes, the pitot probe including means for sensing the total of the dynamic and static pressure of that entire flow;

• a second probe positioned at a second monitoring point adjacent said exit from the condenser, the second probe sensing the static pressure and temperature at said second monitoring point;
• and
• derivation means for deriving an indication of the amount of air flowing past said first monitoring point from said total pressure, and the static pressure and temperature at said second monitoring point.