Emerson 3081FG instruction manual Reestablishing Proper Calibration Check GAS Flow Rate

Instruction Manual

IB-106-3081 Rev. 1.5 September 2002

Model 3081FG

3-3 REESTABLISHING PROPER CALIBRATION CHECK GAS FLOW RATE

The calibration check gas flow must be enough to ensure no combustion flue gases mix with the calibration check gases and only clean, good calibration check gas surrounds the cell without expending excess gas (Figure 3-3). Monitor the O2 concentration using an IRC or HART Com- municator. Set the calibration check gas flow rate as follows:

NOTE

Only set the calibration check gas flow rate at startup. It is not necessary to perform this procedure for each cali- bration check.

a.Adjust the calibration check gas flow to 5 scfh (2.5 L/min.) to ensure the cell is sur- rounded by calibration check gas. Due to the cooling effect of the gas, the cell tem- perature will decrease slightly, causing the O2 concentration to drop. Once the elec- tronics compensates for this effect, the O2 concentration will stabilize.

b.Next, slowly reduce the calibration check gas flow until the O2 concentration changes, which indicates that the calibration check and flue gases are mixing. Increase the flow rate until this effect is eliminated.

FLUE GAS	STACK OR DUCT
	METAL WALL
	PROTECTIVE
	TUBE
	CELL
CALIBRATION	REFRACTORY
GAS
	CALIBRATION
	CHECK GAS LINE
	REFERENCE
	AIR LINE	26020062

Figure 3-3. Proper Calibration Check Gas Flow Rate

3-2 Startup and Operation Rosemount Analytical Inc. A Division of Emerson Process Management