Teledyne BDS-3960 Gas Pressure, Temperature effect, Recovery from High Level Oxygen Exposure

Operational Theory BDS 3960

2.2.3Gas Pressure

The analyzer is equipped with a pressure regulator as shown in Figure 2-3. To access the pressure regulator, the front panel must be opened. The inlet pressure should be regulated anywhere between 4 to 50 psig. The sensor is not affected by pressure changes in the inlet as long as the analyzer vents to atmosphere. If the analyzer is not vented to atmosphere, the downstream pressure must not exceed 10 inch of water. A clogged or restricted vent or excessive pressure will force gas into the electrolyte and cause damage to the BDS sensor.

	Oxygen Scrubber
				Vent
Sample				Flowmeter
Inlet
Span
Inlet			BDS Sensor
		Pressure Regulator

Figure 2-3: A simplified BDS Sample System

2.2.4Temperature effect

The raw output from a BDS oxygen sensor has a temperature coefficient about 0.25% / °C. That is an average value, it changes as temperature changes. This temperature effect is compensated by the software throughout the operation temperature range (5 – 40°C).

2.2.5Recovery from High Level Oxygen Exposure

The ambient air contains about 210,000,000 ppb (2.1 x 108) oxygen. Figure 2.4 is a typical purge-down curve for a new BDS sensor which had been air saturated. It is normal to take several hours, even days for an air saturated BDS to purge down to a low ppb level.

Teledyne Analytical Instruments 22