Teledyne 311 - Portable trace oxygen analyzer - Manual (Page 6)

A current limiting resistor (R1 and R2) is potted into the end of each battery. This assures that
under no circumstances can more than 25 milliamperes (100 milliwatts) be switched or drawn
from either battery supply. This means that the Model 311-C may be used in explosive
atmospheres where arcs of 100 milliwatts or less can be tolerated. The Model 311 meets Factory
Mutual approval requirements as intrinsically safe for Class I, Division I, Groups A, B, C and D
hazardous locations.
This safety feature does not apply when the instrument is being charged (AC power cord
connected and selector switch in the “OFF” position). The instrument should not be used in
explosive atmospheres when the batteries are being charged.
To determine the state of the rechargeable batteries turn the range selector knob
counterclockwise to the battery test position and hold there (spring loaded switch). Observe that
the meter indicator stays within the battery limits, *if not, recharge of the batteries is in order).
Release Range Selector Switch, it will automatically return to the OFF position.
1.3.4 Accuracy and Response. The Model 311 provides monitoring accuracy
of ±2% of full scale or ±1 ppm, whichever is greater, at constant temperature. A ±5% of reading
accuracy is achievable throughout the operating temperature range of 30 to 125 Deg. F.
With a sample flowrate of 150 cc/min. 90% response is achieved in 10 seconds in the X10,
X100, X1000, and CAL range switch positions. When in the X1 (0-10 ppm) range, 90%
response is realized in 61 seconds.
1.3.5 Compact Packaging. The instrument is housed in a 6-1/8” X 9-1/2” X 5-
5/8” aluminum case that is equipped with a carrying handle and foot pads. When in use, the
analyzer should be placed in an upright position on a level surface (off level positioning will
detract from meter accuracy).
Access to the instrument interior is gained by loosening (ccw) the three (3) 1/4 turn screw driver
type fasteners on the back of the outer case. The case may then be detached from the driver type
fasteners on the back of the outer case. The case may then be detached from the control of the
outer case. The case may then be detached from the control panel assembly. Further
disassembly may be accomplished by removing the back plate assembly from its four (4)
mounting standoffs and laying the two separated assemblies out as illustrated on the “Analyzer
Wiring Diagram”. The diagram is included among the drawings at the rear of the manual.
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