HP 5890 II, 5890 II Plus manual 131

Detector Systems

Nitrogen-phosphorus detector (NPD)

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 specific response. 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).

Figure 7-4			Internal
		External
		Plumbing	Plumbing
					Active Element
Final Pressure Regulators
					Power
and Gauges											Detector
Traps								Power to
								Active Element
Compressed				Flow Manifold Block
Air
								AIR
						On/Off			Air
Hydrogen
Gas
								HYDROGEN
						On/OffHydrogen
										From
							(Plus Makeup
										Inlet
							Gas)
Capillary
Makeup
Gas								MAKEUP GAS			Column
						On/Off
	Flow Diagram, Nitrogen-Phosphorus Detector (NPD)

131