1 0991 483
EN
-
21.12.2011
NGV A3
VALVE
M
ANUAL
I
NSTALLATION
, U
SE AND
M
AINTENANCE
9 / 46
1.05
ENG
1.4 THE DOUBLE SAFETY
For the double safety the system has two spools in series, the VRP and the VB.
Both work together to stop the car in different ways between upvward and downward
UPWARD
The spool VB controls acceleration and deceleration.
During the approach to the landing, the spool VB, will be almost fully open to discharge a quantity of oil
equal to:
Qt = Qp - Qc
where
Qt = Oil sent to the drain through the VB, Qp= Pump flow
Qc= Flow to the cylinder, corresponding to the car speed
The car stop at the landing is made by opening completely the VB and bringing the value of Qt = Qp. As a
result Qc becomes zero.
The car stops when the pressure of the chamber C2 become equal to the pressure of the chamber C1
(Static pressure of the system). In this case, the VRP spool closes, because is pushed by the pressure and
by the spring, and the car stops at the landing.
DOWNWARD
The downward phase is simpler and, after the opening of the VRP spool, the car speed is controlled by the
VB spool. To a more opening of the spool corresponds an higher speed of the car
The phase of arrival at the landing is determined by the following events:
The VRP spool is opened by the push of the spools P, controlled by the VMD pilot valve
The VB spool closes to stop the car
The VMD valve, raised the landing, is de-energized and consequently the VRP spool closes.
During standard operation of the system, both upward and downward, the proper working of the two
spools (VRP and VB) acting in series, is controlled by three switches :
One, (S1) installed on the VRP, to control the full close position.
Two (S2, S3) installed on the VB, to control the full close and the full open positions
During all phases the system control that the spools reach the correct open and close position.
If this do not happen, the system send an alarm to the control panel, which must turn the system into the
out of service status
WARNING
Needful prerequisite of the control panel, when the system is outside of the doors unlocking zone, is
that it does not send commands to the card and/or the motor / pump.
1.5 MAIN FEATURES
Valve Type NGV A3
Minimum operating pressure 12 bar
Maximum operating pressure 45 bar
Test speed 1 m/s
Temperature operating range 5°C - 70°C
Rated pump flow range 55 - 300 l/min
¥
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Summary of Contents for NGV A3
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