SAFETY FEATURE CHECKS
IMPORTANT: These are safety
features, which you should routinely check
to assure proper function. If any of these
safety features are not functioning properly,
contact your Dental Dealer or Porter
Instrument and arrange for the necessary
repairs. Porter Instrument recommends the
repairs be made before reusing the device.
NITROUS OXIDE FAILSAFE SYSTEM
CHECK BEFORE EACH USE
1. Set the right-hand total Flow Control
Knob to zero and set the left-hand
Concentration Control Knob to zero.
(See Figure 1-Items 4 and 5: Rotate
control knobs to stop.)
2. Be sure O
2
and N
2
O are connected to
your MXR and line pressure for both
gases is 50 PSIG (which is standard).
3. Turn the Concentration Control Knob to
50%. There should be no flow of
N
2
O. This is a check of the static
position of the Nitrous Oxide Failsafe
System valve.
NOTE: A momentary low flow of N
2
O
(about 1 L/min for about a second) may
be seen if the Concentration Control
Knob is turned to zero before turning the
Flow Control Knob to zero. This is N
2
O
gas trapped between the Nitrous Oxide
Failsafe System valve and the
Concentration Control Knob valve and is
a normal occurrence. No other N
2
O
flow should be observed.
4. With the Concentration Control Knob
still set to 50%, turn the Flow Control
Knob to achieve a flow of 3 to 4 L/min of
O
2
. You should observe an equal
amount of N
2
O flowing by gradually
turning the Flow Control Knob. (Refer
to Monthly Calibration Check on Page
13, to read ball float on flowmeter
tubes.)
5. Interrupt the flow of O
2
. This will check
the dynamic status of the Nitrous Oxide
Failsafe System valve. This can be
done by either disconnecting the oxygen
hose from the wall or shutting off the
oxygen at the tank. The Nitrous Oxide
flow should drop as the Oxygen flow
decreases, stopping completely
before the Oxygen float drops to
zero.
WARNING
If the Nitrous Oxide Failsafe System fails to
perform as indicated, do not use this
product prior to repair. Improper function of
this safety feature may permit Nitrous Oxide
to flow independently of the flow control
knob, potentially allowing Nitrous Oxide to
flow to the patient without Oxygen.
CONCENTRATION CONTROL KNOB
VALVE – CHECK MONTHLY
Set the Concentration Control Knob to 50%,
and Flow Control Knob to 2 to 3 L/min. The
ball indicators will be at about the same
height (If not, refer to Monthly Calibration
Check section on Page 13 for the
procedure on checking the accuracy of the
meter.). Turn the Concentration Control
Knob to zero. The N
2
O flow should drop to
zero. You essentially perform the check at
the end of every procedure when you
oxygenate the patient with 100% O
2
.
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