- Hewlett-Packard Reference Manual

Detector Systems
Nitrogen-phosphorus detector (NPD)
131
Other gas flow effects of too high flow rates of the hydrogen may allow a
true flame to exist around the active element. This would overheat the
active element severely and destroy the specificresponse. Too low flow
rates of air tend to quench the background response of the active
element, and this results in a re•equilibrationtime that is too long to
establish proper background response (negative solvent peaks killing the
active element).
Compressed
Air
Hydrogen
Gas
Capillary
Makeup
Gas
Flow Manifold Block
On/Off
On/Off
On/Off
MAKEUP GAS
HYDROGEN
AIR
Air
Hydrogen
(Plus Makeup
Gas)
Detector
From
Inlet
Column
External
Plumbing
Internal
Plumbing
Power to
Active Element
Active Element
Power
Flow Diagram, Nitrogen-Phosphorus Detector (NPD)
Figure 7-4
Traps
Final Pressure Regulators
and Gauges