Siemens RAPIDLAB 248, Operator'S Manual, Page: 50 / 135

Page 3-12 248 Operator’s Manual
Changing the Cylinders
f. When the cylinder is completely vented, and the pressure is
reduced to zero, label the cylinder ‘empty’ and dispose of it
according to your laboratory protocol.
3. Install the new cylinder. Make sure you replace the cylinder with
the correct type.
a. Place the gas cylinder into its final position and secure.
b. Remove the plastic protective wrapping from the valve assembly.
c. Check the gas cylinder seal is in place on the regulator.
d. Attach the gas regulator to the cylinder with the regulator nipple
engaging the opening in the cylinder valve.
e. Tighten the yoke screw firmly.
f. Slowly open the cylinder valve until the pressure gauge indicator
stops rising (approximately 3/4 of a turn, average psi is 2000).
g. Open the cylinder valve one more turn.
h. Listen carefully for any gas leakage. Use soapy water to check
for bubbles.
CAUTION:
The needle valve is easily damaged. Turn the valve
gently when opening.
i. Check the needle valve is fully open.
j. If the gas will not be used for an extended period of time, close
the cylinder by turning the cylinder valve clockwise, otherwise
continue.
4. Restart the 248 system.
Checking the Gas Flow Rate
1. Initiate a full 2 point calibration:
From
Ready
press
#
for
menu
,
1
for
Calibration
and
2
for
Full 2
Point .
2. The gas flow rate is checked while the gas is being measured:
a. When the calibration gas values appear on the display lift the
probe lever to the first position.
b. Fit a capillary adaptor to the end of the probe (this makes the
bubbles easier to count).
c. Present a small beaker of deionized water to the probe. The
bubbles should flow at a rate of no less than 2 per second.
d. Remove the capillary adaptor and close the probe.
3. Repeat for the slope gas:
a. When the slope gas values appear on the display lift the probe
and repeat steps 2b to 2d.
4. If either of the gas flow rates is incorrect contact your Siemens
distributor.