2
Functional Description
Mass Spectrometer
44
TSQ Quantum XLS Series User Guide
Thermo Scientific
Vent Valve
The vent valve, located in the area of Q2, allows the vacuum manifold to be vented with
nitrogen, if you have a nitrogen cylinder connected, or else with air that has been filtered
through a sintered nylon filter. The vent valve is a solenoid-operated valve, which is controlled
by the Vent Delay PCB. When the solenoid is energized, the vent valve closes. If the power
fails or the main power circuit breaker is placed in the Off (O) position, a 4-farad capacitor
located in the Power Entry Module keeps the solenoid in the closed position for several
minutes. If power is not restored in this time, then the solenoid opens and the system is
vented with nitrogen or filtered air. The vent valve closes after power is restored to the mass
spectrometer.
Collision Gas Flow Control Valves
The collision gas flow control valves control the flow of argon collision gas into and out of the
Q2 collision cell. A solenoid valve acts to shut off argon gas flow to the cell. The collision gas
pressure is regulated by a proportional valve that is controlled by the data system. You can set
the collision gas pressure (0 to 5 mTorr) in the Define Scan dialog box of the EZ Tune
window.
Ions enter the Q2 collision cell, collide with the argon collision gas, and then, because of the
collision, dissociate into smaller fragments. See
“Collision Cell and CID Efficiency”
Argon enters the mass spectrometer through a 1/8 in. port on the left side of the mass
spectrometer.
A second proportional valve allows the forepump to evacuate the Q2 collision cell of argon
and waste gases when CID is turned off. The mass spectrometer automatically opens and
closes the collision gas evacuation valve, depending on whether Q2 is acting as an ion
transmission device or a collision cell.
Calibration Compound and CI Reagent Gas Flow Control
The calibration compound gas flow control valve controls the flow of calibration compound
gas into the ion source, via the transfer line. The calibration gas flow can be either high or low.
Normally, you use low flow, but high flow might be necessary for negative ion CI calibration.
The CI gas flow control valve controls the flow of chemical ionization reagent gas into the ion
source, via the transfer line. The maximum CI gas flow rate is about 4 mL/min, depending on
the gas.
