RKI Instruments GP-204 - Manual (Page 4)

Gas Detection For Life
RKI Instruments, Inc. • 33248 Central Ave. Union City, CA • Phone (510) 441-5656 • (800) 754-5165 • Fax (510) 441-5650
World Leader In Gas Detection & Sensor Technology
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5) Recalibrate the new sensor using span gas.
C. Batteries
The model GP-204 is furnished with two standard size D batteries, either alkaline or Ni-Cad. These
batteries will give 4 to 5 hours of operating life before replacement or recharge.
When meter cannot be set as high as the "CHECK" line with switch in VOLT ADJ. position and VOLT
ADJ. knob all the way clockwise. batteries require replacement or recharging.
To replace batteries, remove instrument from leather case, and loosen the coin slotted captive screw
found in center of bottom plate. Remove plate, exposing batteries in their spring contact holders.
Pull old batteries out, and install new ones in the same position, observing polarity as marked on
holder.
D. Sample system
1) Hose
The hose used is teflon-lined, synthetic rubber jacketed, and immune to absorption or attack
by any combustible vapors or solvents. Keep hose clean and be sure that couplings make air
tight contact, checking occasionally by holding finger over hose inlet. Bulb should remain
flattened after squeezing if there is no leak. Extension hoses in various lengths are available.
2) Flame arrestor / Sensor assembly
The active filament is installed within a sintered bronze porous metal cup, which acts as a
flame arrestor to retain explosions that may occur when sampling explosive gas and air
mixtures. The flame arrestor is part of the sensor assembly, which may be removed by taking
out the four screws that hold the sensor plate. If the flame arrestor is dusty, wet, oily or
corroded, it must replaced by replacing the sensor assembly. Before reinstalling sensor in
instrument, be sure that the reaction chamber cavity and incoming lines are clean and dry.
E. Meter lamp
The meter lamp is on whenever the instrument is on, and provides illumination to permit meter
reading in dark places. If lamp fails, it should be replaced as follows:
Remove four screws holding top plate to the top panel. Take off top plate exposing lamp. Loosen
set screws, which lock lamp wires to terminals, and pull lamp out. Install new lamp in the same
position.
5. PRECAUTIONS AND NOTES ON OPERATION
A. Heated samples
When sampling spaces such as hot tanks that are warmer than the instrument, remember that
condensation can occur as the sample passes through the cool sample line. Water vapor condensed
in this way can block the flow system and corrode the flame arrestor. A water trap can be used to
control this, and is available as an accessory.
If heated hydrocarbon vapors of the heavier hydrocarbons (flash point 90° F or above) are present,
they may also condense in the sample line and fail to reached the filament. Thus an erroneous low
reading may be obtained.
B. Element poisoning