MAO/TRACEGAS/S1 - NOy spurious signals

NOy MFM (and the Pressure sensor) began to report spurious signals. This appears related 
to water infiltration. The Operator installed a 'beer can' rain diverter in early March to 
remedy the problem. The loss of this sensor is inconsequential as the flow is controlled 
and measured by an upstream Mass Flow Controller in the inlet.

• One minute sample flow average from NOx TEI (this varies as the PreR valve
  switches, so questionable)(nox_flow)
• One minute average reaction pressure from NOx TEI(nox_pressure)