Edwards nEXT nEXT85 - Vent Valve Control

applicable orice size to be installed to the vent valve. Make sure that the rate of
increase in pressure is in the limits shown in Vent gas specicaon and vent control data
on page 20.
Note:
If a vent restrictor is used, the me necessary to vent the vacuum system can be long. To
decrease the me:
- use vent valve without a vent restrictor.
- wait unl the pump speed decreases to 50% of the full rotaonal speed before you
open the vent valve.
6.2.3 Vent valve control
The TAV5 solenoid valve can be controlled by the motor controller or by the
manufacturer's TIC Turbo Instrument Controller.
The controller can control the rate of venng, using the vent valve opons given in
Table: Vent valve opons on page 69. With this feature, the pump can be vented from
full rotaonal speed in a controlled manner that will not damage the pump bearings. It
is safe to hard vent (open the vent valve fully) when:
▪ the rotaonal speed of the pump decreases below 50% of maximum speed and
▪ the backing pump is on and the backing valve is open.
To use the controller funcon, the turbo pump controller has a 4-pin auxiliary connector
socket on the side of the pump. The vent valve with the auxiliary connector installed is
plugged into the 4-pin auxiliary connector socket. Refer to Figure: Auxiliary interface
connecon on page 71.
The controller can control number of dierent venng opons. Refer to Table: Vent valve
opons on page 69.
The controller can accommodate normally open and normally closed vent valve types.
Refer to Table: Valve types on page 70. A power cycle is necessary aer making a change
to the valve type, before the auxiliary output circuitry adjusts to accommodate the
requested change.
Table 23
Vent valve opons
Opon
number
Descripon of vent funcon
0 Vent valve opens fully below 50% full rotaonal speed for a stop
command or fail condion.
*
1 Controlled venng from 100% to 50% full rotaonal speed and then
vent valve opens fully below 50% for a stop command or fail
condion.
2 If a stop command is received, vent valve fully opens. In a fail
condion, vent valve opens fully below 50% full rotaonal speed.
3 If a stop command is received, vent valve fully opens. In a fail
condion, controlled venng from 100% to 50% full rotaonal speed
and then vent valve opens fully below 50%.
Page 69
B8G000880_D - Operaon