Theory of operation
Puritan Bennett™ 700 Series Ventilator System Service Manual
10070389 Rev. A
2-11
NOTE:
To prevent depletion of oxygen supply, disconnect oxygen from ventilator when
oxygen is not in use. Any time oxygen is connected, whether or not an oxygen-enriched
patient mixture is selected, the oxygen regulator bleeds up to 3 L/min.
The regulator has a pressure tap to permit the attachment of a fixture for oxygen
regulator pressure transducer calibration.
The regulator has a pressure drop of 6 to 7 psig when the high-flow oxygen solenoid is
energized (at 150 sL/min).
• The
oxygen solenoid assembly
includes two two-way solenoids and two critical flow
orifices. Whenever the ventilator is set for an oxygen concentration greater than 21%,
these solenoids/orifices deliver oxygen to the mixing manifold. Only one of these
solenoids is energized with each breath. The larger (high-flow) solenoid and orifice can
deliver higher flows, while the smaller (low-flow) solenoid and orifice can deliver lower
flows. For more information about the oxygen solenoids and oxygen mixing, see
Section 2.6.4.
• The
oxygen regulator pressure transducer
measures the oxygen pressure at the oxygen
solenoid assembly. These oxygen pressure measurements are used to monitor the oxygen
source pressure to verify its adequacy and to calculate the flow from the orifices. If the
oxygen pressure reading drops below a threshhold level (determined by real-time
atmospheric pressure measurements) for two consecutive breaths, or if oxygen flow from
the high-flow orifice drops below 100 L/min for two consecutive breaths, the ventilator
invokes a low oxygen supply alarm.
• Filtered room air and the precisely controlled oxygen flow pass through the
mixing
manifold
. This chamber has a muffler, which dampens the sound of the mixing gases. An
upgraded
acoustic enhancement kit
is available that replaces the phase one kit (p/n
G-062027-00.) The new kit contains improvements to the oxygen solenoid assembly and
the oxygen mixing system which reduce the sound level of the ventilator’s normal
operation. When performing a complete acoustic upgrade, order the required acoustic kit
and an air intake manifold assembly. If the ventilator was shipped after November 1998,
or if a phase one acoustic kit was installed previously, a new manifold is not required. See
Table 9-2 for ordering information. If you are installing the acoustic enhancement kit, you
also need to install the following assemblies:
• Oxygen Solenoid Assembly (See Section 8.7.1 and Section 8.7.2)
• Mixing Manifold Assembly (See Section 8.7.1 and Section 8.7.2)
• Inspiration Access Panel Kit (See Section 8.6.6)
• Regulator Grounding Harness
• Air Intake Manifold Assembly (See Section 8.6.6)
Summary of Contents for Puritan Bennett 700 Series
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