RKI Instruments HS-94 - Manual (Page 11)

30 or 60 (for H2S) or 150 (for CO). Once you have scrolled to the value of your
calibration gas, go to step 9.
9. Press the MODE switch, and the instrument should read the gas levels in the
surrounding air. Now apply the span gas to the instrument using an appropriate
test cup to fit over the sensor area. Allow sufficient time for full response (30 to
60 seconds).
10. Press the AIR switch and hold for 5 beeps. The last 2 quick beeps indicate that
the unit has adjusted the span to the level that it was set to believe was in the
cylinder from step 8 above.
11. Turn off the gas supply, and press the mode switch once to return to
normal operation. Calibration is complete.
Note
The 94 series instruments will display up to 199.0 ppm H
2
S and 499 ppm CO, but the
limit of linear response is 30 ppm for H
2
S and 150 ppm for CO; well above acceptable
exposure levels. Readings above these levels could be inaccurate and should only be
referenced for trends .
Battery Replacement
To replace the batteries, loosen the screw on the side of the instrument with a
screwdriver, fingernail, a coin or other appropriate device. Slide and remove the
battery cover from the instrument. Remove the batteries and verify that the battery
compartment and electrical contacts are clean. If necessary, use a soft wire brush to
gently clean the compartment and contacts. Insert fresh batteries (2 “AAA” sized
alkalines) according to the polarity (+/-) markings, and replace the cover.
Sensor Maintenance
Electrochemical sensors (O
2
, H
2
S, CO) gradually deteriorate, regardless of use, and
require periodic replacement.
The 94 Series sensors are easy to replace. If a sensor requires replacement, call RKI or
your local distributor to obtain a replacement sensor. All sensors are warranted usable
for one year from the date of shipment. Sensors that fail within the warranty period
will be replaced at no charge.
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