Emerson Process Management IB106-340 Section Maintenance and Service, Calibration

Oxymitter 4000

Instruction Manual

IB-106-340 Rev. 2.4 April, 2001

SECTION 6

MAINTENANCE AND SERVICE

6-1 OVERVIEW

This section identifies the calibration methods available and provides the procedures to main- tain and service the Oxymitter 4000 and optional integrally mounted SPS 4000.

Install all protective equipment covers and safety ground leads after equip- ment repair or service. Failure to in- stall covers and ground leads could result in serious injury or death.

6-2 CALIBRATION

a.During a calibration, two calibration gases with known O2 concentrations are applied to the Oxymitter 4000. Slope and constant values calculated from the two calibration gases determine if the Oxymitter 4000 is correctly measuring the net concentration of O2 in the industrial process.

Before calibrating the Oxymitter 4000, verify that the calibration gas parameters are cor- rect by setting the gas concentrations used when calibrating the unit (See paragraph

4-1a.5)and by setting the calibration gas flowmeter.

The calibration gas flowmeter regulates the calibration gas flow and must be set to

5 scfh. However, only adjust the flowmeter to 5 scfh after placing a new diffusion ele- ment on the end of the Oxymitter 4000.

Adjusting the flowmeter at any other time can pressurize the cell and bias the calibration.

In applications with a heavy dust loading, the O2 probe diffusion element may become plugged over time, causing a slower speed of response. The best way to detect a plugged diffusion element is to note the time it takes the Oxymitter 4000 to return to the normal process reading after the last cali- bration gas is removed and the calibration gas line is blocked off. A plugged element also can be indicated by a slightly lower reading on the flowmeter.

Change the diffusion element when the cali- bration gas flowmeter reads slightly lower during calibration or when the response time to the process flue gases becomes very slow. Each time the diffusion element is changed, reset the calibration gas flowmeter to 5 scfh and calibrate the Oxymitter 4000. To change the diffusion element, refer to paragraph 6-8.

b.Three types of calibration methods are available: automatic, semi-automatic, and manual.

NOTE

A calibration can be aborted any time during the process by pressing the CAL key (Figure 6-2)on the Oxymitter 4000 keypad three times in a three second interval or via HART/AMS or an IMPS 4000. An aborted calibration will retain the values of the previous good calibration.

1. Automatic Calibration. Automatic cali-		6
brations require no operator action.
However, the calibration gases must
be permanently piped to the Oxymitter
4000, an SPS 4000 or IMPS 4000
must be installed to sequence the
gases, and the Oxymitter 4000’s logic
I/O must be set to mode 8 via HART/
AMS so the sequencer and Oxymitter
4000 can communicate.
Depending on your system setup, an
automatic calibration can be initiated
by the following methods:
(a)	The Oxymitter 4000’s CALIBRA-
	TION RECOMMENDED alarm sig-
	nals that a calibration is required.
(b)	Enter a “time since last cal” pa-
	rameter (CAL INTRVL) via HART/

AMS that will initiate an automatic calibration at a scheduled time in- terval (in hours). To configure the CAL INTRVL parameter, refer to paragraph 5-8.

Rosemount Analytical Inc. A Division of Emerson Process Management Maintenance and Service 6-1