Bio-Rad Helios® Gene Gun System - Manual (Page 21)

4. The nitrogen regulator should be turned on and adjusted to the correct pressure prior to con-
necting the nitrogen line to the Tubing Prep Station. Close the nitrogen pressure regulator by
turning the regulator adjustment screw counterclockwise until the adjusting spring pressure is
released and the screw moves without resistance. Release nitrogen into the pressure regulator
by carefully and slowly opening the cylinder valve on the nitrogen tank. The cylinder pressure
in the tank is indicated on the high pressure gauge (the gauge closest to the cylinder). Hold the
nitrogen line in your hand and slowly turn the regulator adjustment screw clockwise until
nitrogen can just be heard flowing from the nitrogen line. Clamp the nitrogen line with your
fingers; the pressure on the output (low pressure) gauge should register no more than 1–2 psi.
If the pressure is too high, turn the regulator screw counterclockwise to reduce the pressure.
5. Connect the male Luer-Lok fitting on the the nitrogen line to the female Luer fitting on the
side of the Tubing Prep Station. The flow of nitrogen into the Tubing Prep Station can be
adjusted with the valve on the flowmeter.
Section 5
Operation of the Helios Gene Gun System
5.1 Quick Guide to Operation
Before the Bombardment
1. Coat microcarriers with DNA, load into tubes, and prepare cartridges prior to day of exper-
iment.
2. Check helium supply (50 psi in excess of desired delivery pressure).
3. Clean and/or sterilize the Gene Gun, tube holders, and barrel liners as appropriate.
4. Connect the Gene Gun to a helium source.
5. Activate the Gene Gun: turn on the flow of helium to the desired pressure and with an empty
cartridge holder in place, make 2–3 “pre-shots” by engaging the safety interlock and firing
the trigger.
Firing the Device
1. Load cartridges into the cartridge holder and place in Gene Gun.
2. Prepare/position target cells for bombardment.
3. Bombard sample: engage safety interlock and press the firing trigger
After the Bombardment
1. Remove cartridge holder from Gene Gun.
2. Remove cartridges from cartridge holder.
3. Turn off the helium pressure to the system.
4. Turn the regulator value counterclockwise to de-pressurize the system.
5. Disconnect the helium hose and Gene Gun.
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