RKI Instruments GP-204 - Manual (Page 2)

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
www.rkiinstruments.com
1. GENERAL DESCRIPTION
The model GP-204 HAND HELD PORTABLE COMBUSTIBLE GAS DETECTOR is a compact battery
operated portable instrument used for taking an air sample and indicating the presence and concentration of
combustible gas. Samples of the air under test are drawn by means or a rubber aspirator bulb and analyzed
for combustible gas content on a heated platinum filament in a Wheatstone bridge measuring circuit. A
built-in meter indicates combustible gas content in units of explosibility. Power for operation or the
instrument is provided by two size “D” alkaline or Ni-Cad batteries. A probe and extension hose permit
withdrawal of samples from remote locations and the instrument fits in a compact leather case with over the
shoulder carrying strap. The model GP-204 is suitable and recommended for testing tanks, manholes,
vessels, pressure cylinders, pipelines, and other closed systems or confined spaces to determine presence
or absence of combustible gas. It is a valuable aid for safety of operations whenever combustible gases or
vapors are handled.
2. OPERATION
Before taking instrument on the job, check battery voltage. To check, put switch in VOLT ADJ position.
Meter should rise to the "CHECK" position near top of scale. Lift and turn VOLT ADJ control clockwise to
determine maximum voltage setting. If it cannot be set beyond mark, batteries need recharging or
replacement. Do not attempt to use instrument at all if voltage reading cannot be set up to mark.
If voltage is satisfactory, continue with the next steps of preliminary adjustment as follows:
A. Confirm operation of pilot light/meter illuminating lamp.
B. With sample inlet in fresh air, squeeze bulb several times to flush out any remaining gas.
C. Check zero setting by turning switch to ON position. Meter should read close to zero. Lift and
turn ZERO knob to bring reading to exactly 0.
D. Couple sampling hose to instrument inlet on left hand end, and connect probe to end of hose.
Hold finger over probe to block flow and squeeze bulb. Bulb should remain squeezed while finger
blocks inlet.
E. Admit a sample of some combustible gas to end of probe, and confirm that meter rises upscale.
Instrument is adjusted and ready to use. lt may be turned off and carried to the job.
To make a gas test, proceed as follows:
1) Turn to VOLT ADJ. position, adjust voltage if necessary, then turn to ON.
2) Hold probe within space to be tested. Squeeze bulb several times while watching meter, and
observe maximum reading.
3) After completion of test, remove probe from test space, flush with fresh air for 4 or 5 squeezes of
bulb, and turn off.