• The low Flow Detection Flowrate is the lowest flowrate
before the Flow detector activates high pressure.
• The final low pressure setting on the ACP must be at
least 10 PSI (0,68 bar) higher than the setting cor-
responding to the Flow Detection Flowrate. This
margin will compensate from line losses variations in
the system during normal operation, that could other-
wise prevent the system from going to high flow.
NOTICE :
FAILURE TO HAVE A SUFFICIENT MARGIN BETWEEN THE
FLOW WANTED AT LOW ENGINE SPEED/IDLE AND THE FLOW
DETECTION FLOWRATE WILL LEAD TO UNSTABLE HIGH FLOW
OPERATION, DEPENDING ON LINE LOSSES AND VARIATIONS
OF THE SYSTEM.
If the flowrate is not acceptable, refer to the appropriate
IOM for the Flow Detector setting procedure.
If the low flow regulator of the ACP does not allow an
increase of 10 PSI (0,34 bar) from the pressure setting
the Flow detector, reduce the Flow Detector setting as
described in the Flow Detector IOM.
After setting the regulator pressure, push down on the
air regulator adjusting knob to lock it in position.
The line going from the Flow Detector to the ACP has
restricted flow.
NOTICE :
AIR LEAKAGE FROM THE FLOW DETECTOR TO THE AIR
CONTROL PANEL WILL NOT BE COMPENSATED BY EXTRA
FLOW COMING FROM FLOW DETECTOR AND WILL CREATE
SYSTEM FAILURE : "NO HIGH FLOW".
No accessories or T-connections are allowed between
the Air Control Panel and the outlet of the Flow Detector.
4.6 AIR SEPARATION - STOPPING FLOW
WHEN AIR ENTERS DMX
When no liquid is present or air is detected in the DMX,
the main float will go down, which will release the pres-
sure on the TXD pump air/relief valve. The pump dis-
charge pressure will be less than the pressure required
to open the flow detector check valve. Flow will stop.
Refer to DMX and Flow detector IOM to meet the instal-
lation requirements of the DMX components.
4.7 AIR SEPARATION - AIR FREE METERED
DELIVERY
To perform its air elimination function properly and prevent
air being pumped through the meter, the DMX requires a
minimum discharge pressure downstream of the pump to
be above a given minimum once the system is primed.
Performance tests have demonstrated that the following
pressure settings are typical for operation with DMX and
TXD pumps :
NOTICE :
IT IS THE INSTALLER'S RESPONSIBILITY ON EACH TRUCK TO
CHECK THAT THE PUMP BACKPRESSURE IS SUFFICIENT TO
ALLOW THE DMX TO PERFORM ITS AIR ELIMINATION FUNC-
TION PROPERLY. ADDING MORE BACKPRESSURE WILL
RESULT IN UNACCEPTABLE PERFORMANCE DURING
WEIGHTS AND MEASURES SPLIT COMPARTMENT TESTING.
The Blackmer Flow Detector acts as a proper pressure
and check valve for TXD2 and TXD2,5 pumps. See the
DMX system and Flow detector IOM for details.
An additional pressure valve with a minimum setting of
22 PSI (1.5 bar) must be used between the meter and
the Flow Detector when the DMX is used in combination
with TXD3 pumps.
The pressure valve setting may be obtained by using
several pressure valves, with a cumulative pressure
above the required setting for the pump used in conjunc-
tion with the DMX.
To evacuate the air trapped between the DMX and the
meter, a Scavenging Line is required. See DMX IOM for
rules on how to install a scavenging line.
The scavenging line must be connected to the piping at
the highest point directly before the meter. The piping
MUST be horizontal.
The piping between the DMX and the scavenging line
must not have a point higher than the scavenging line
connection.
NOTICE :
FAILURE TO MEET SCAVENGING LINE INSTALLATION CRITERIA
WILL LEAD TO AIR ELIMINATION SYSTEM FAILURE (A DIFFE-
RENCE BETWEEN PROVER AND METER READING IN SPLIT
TEST CONDITIONS).
4.8 OPERATION AGAINST A CLOSED DISCHARGE
VALVE
The pump internal relief valve protects the pump when the
nozzle is closed and the truck is running. The high pres-
sure regulator of the ACP must be set below the maxi-
mum acceptable pneumatic pressure of the pump
air/relief valve. See the TX Air/Relief Valve IOM for details.
4.9 LIQUID HANDLING FROM DMX TO FLOW
DETECTOR
Follow piping and installation requirements described in
the appropriate IOM.
Pump back pressure required for
proper air elimination (TXD2 & 2.5)
10 PSI (0.7 bar)
Pump back pressure required for
proper air elimination (TXD3)
32 PSI (2.2 bar)
7/15
NT 201B-A00 04.06 DMX IV Air elimination system e
4. SYSTEM CONSIDERATIONS (continued)
