Rp20 Demand Fcv R/R; Rp21 Demand Fcv Filter Screen Replacement - CAIRE HELiOS Plus Technical & Service Manual

XI
Troubleshooting & Repair Procedures
RP20 – Demand FCV R/R
1. Remove the covers (RP4).
2. Remove the flow control knob by pulling it straight back
from the front cover.
3. Pull the demand flow control valve backwards out of its seat
inside the front cover.
4. Use a small flat head screwdriver to carefully pry the polyu-
rethane tube off of the demand flow control valve inlet
barbed fitting.
5. Use a small flat head screwdriver to carefully pry the sili-
cone tubes off of the cannula barb fittings.
6. Install the new flow control valve by reversing steps 1-5.
NOTE: The demand flow control valve is not field serviceable.
Only the barbs and inlet filter screen may be replaces as needed.
CAUTION: The demand flow control valve is manufactured to
exacting tolerances and uses a number of small orifices. Ensure
that hands, tools, and work table are clean when working with
the valve. Do not allow liquids to enter the vent port located
directly across from the vent valve inlet fitting.
RP21 – Demand FCV Filter Screen Replacement
1. Remove the demand FCV (RP20).
2. Remove the inlet barbed fitting by unscrewing it from the
FCV.
3. Hold the valve so that the inlet port faces downward.
4. Use a dental pick or other similar tool to carefully remove
the inlet filter screen.
Figure 47: Inlet Filter Screen Removal
5. Push the replacement filter screen into the inlet port until it
is seated on the internal support ledge.
NOTE: Do not install two filter screens. This may cause a flow
restriction.
6. Re-install the inlet barbed fitting.
NOTE: When installing the brass barbed fitting, verify the
presence and condition of the seal gasket on the threaded end
of the fitting.
7. Replace the FCV (RP20).
RP21A- Sensitivity Adjustment
CAUTION: Damage to demand flow control valve possible.
One port of the jet/venturi assembly tee connector and the lon
port of the jet/venturi act as bleeds and must remain open.
NOTE: The Magnehelic gauge must be leveled and zeroed
in the vertical position before making any adjustments to
the demand flow control valve. Check the gauge calibration
periodically according to the manufacturer's specifications or
if it has been dropped or mishandled.
1. Make sure that the H300 or H850 has been tested for leaks
before continuing.
2. Set the demand flow control valve knob to 0 and fill the unit
with liquid oxygen saturated at 22-30 psig (152-207 kPa).
Let the system pressure for 10 minutes.
3. Connect the jet/venturi test setup to the H300 or H850 sense
(bottom) connector. Connect the test flowmeter to the
oxygen outlet (top) connector
4. Set the demand flow control valve to D4 on H850 or H300
set the demand flow control valve to 4 and lay the unit on its
back. Increase the oxygen source pressure to the jet/venturi
assembly until approximately 2L/min of flow registers
on the test flowmeter. Let the unit run at this flow for ten
minutes. This will bring the system pressure down to the
economizer setting (H850 22.3-24.8psig/154-171 kPa) and
(H300 20.5-23psig/154-171 kPa).
5. Decrease the oxygen source pressure to the jet/venturi
assembly to 0 psig. The test flowmeter should read 0 L/min
and the Magnehelic gauge should read 0-in. H2O.
6. With the Magnehelic gauge reading 0-in. H2O, slowly
increase the oxygen source pressure to the jet/venturi
assembly until oxygen flow (at least .25 L/min) first
HELiOS Portables Technical Service Manual • PN 20562190 Rev E
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