CROSSED LINES WARNING
N E W O R M O D I F I E D I N S T A L L A T I O N S
ALWAYS ASSURE THAT LINES ARE NOT CROSSED!
WARNING:
New or modified installations -
properly connected gas pipelines are absolutely essential
to patient safety.
The dealer or contractor should provide written documentation that all gas pipelines are
connected properly and that the system has been pressure tested prior to use. While this is a good
business practice, it is important that the user verify by their own test, independent of the dealer or
contractor, that all gas pipelines are connected correctly prior to using the system.
The ultimate
responsibility of assuring that lines are not crossed rests with the user.
Do not allow crossed lines to defeat the safety features of the dental flowmeter and / or central gas
supply manifold systems. Crossed lines will create a dangerous and hazardous condition where
100% Nitrous Oxide will be delivered through the Oxygen dental flowmeter tube and subsequently
to the patient. In addition, the resuscitator quick connect would deliver 100% Nitrous Oxide to an
Oxygen demand valve.
Maintain patient observation during procedures. Prevent over sedation. If a patient becomes over
sedated when being delivered 100% Oxygen, it is a definite indication of crossed lines. If crossed
lines are suspected, remove the nasal mask immediately and encourage mouth breathing. Deliver
pure Oxygen from an Oxygen demand valve only if the Oxygen source is independent from the
suspected crossed lines area.
To check for crossed lines of an installed Porter Vanguard (or Sentinel) Manifold System:
1. At the manifold system (in the tank room), start the check from an operating system with 50 PSI
showing on both gauges and the indicator lights turned on – electrical operation and alarms needed for
the Vanguard test. Then, turn off both Oxygen tanks and leave both Nitrous Oxide tanks on. (For the
Sentinel, only one tank of each gas is on at a time. Turn off the one open Oxygen tank, leave on the
one Nitrous Oxide tank, turn off the indicator lights – eliminates alarms during the Sentinel test.)
2. In the operatory, where the flowmeter is installed, flow 5 to 6 liters per minute of O
2
only. Verify that the
N
2
O flowmeter valve is in the off position and that there is no indicated flow of N
2
O - by observing the
ball float resting at the bottom of the glass N
2
O flow tube.
This action will bleed the Oxygen copper tubing lines (1/2” OD) from the manifold, through the office
walls, to the flowmeter. Note: this action does not cause a quick bleed down, as there is a fair sized
volume in the lines. O
2
flow would be observed by the position of the ball float in the O
2
flow tube for
several minutes.
3. Rather than waiting for the O
2
flow to decrease, go back to the manifold tank room and observe the O
2
pressure gauge on the manifold (normally showing approximately 50 PSIG pressure). The line
pressure should start to decrease, indicating bleeding of the O
2
that is no longer being replenished by
the tanks. On Vanguard systems, the alarm will beep at 40 PSIG, a switch will occur from one tank to
the second tank at a timed interval (increasing the gauge back to 50 PSIG). The gauge then should
eventually go down to zero.
If the O
2
pressure does not go down as described above, and remains at about 50 PSIG, it indicates a
crossed lines condition.
4. If
O
2
pressure does not go down, proceed to the next crossed line determination check. Turn N
2
O
tanks off in the manifold tank room and watch the N
2
O
gauge. Given a crossed line condition, the N
2
O
gauge will now go down (the Vanguard system will show a switching similar to step 2 above) — this
shows the O
2
valve of the flowmeter is bleeding the crossed N
2
O lines. The N
2
O gauge will go down to
zero.
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