BIO RAD Helios Gene Gun System Instruction Manual page 33

i. Push in and release the cylinder advance lever to ratchet the cartridge holder one position, bringing
the first cartridge into firing position. The number 12 should be seen at the top point of the cartridge
holder. The gene gun is now ready for pressurizing with helium. Note: do not wiggle the cartridge
holder after the cartridge is in firing position. The Helios Gene Gun has a self-centering mechanism
which places the cartridge in the proper position for firing.
2. Set up the Helios Gene Gun and connect to a helium source as described in Connecting the Helios
Gene Gun to a Helium Source, in Section 4. Refer to Identification of System Components and Controls,
in Section 3 for identification of controls on the gene gun.
3. Start the flow of helium as follows: (Note: If a continous gas leak is observed after opening either the
cylinder valve or the regulator adjustment screw, close the appropriate valve and check the tightness of
the fitting. Contact Bio-Rad if a system leak persists.)
a. Close the helium pressure regulator by turning the regulator adjustment screw counterclockwise until
the adjusting spring pressure is released and the screw moves without resistance.
b. Release helium into the pressure regulator by slowly opening the cylinder valve on the helium tank;
open the valve fully. The helium pressure in the tank is indicated on the high pressure gauge (the one
closest to the cylinder). Verify that the pressure in the tank is at least as high as the desired discharge
pressure.
c. Open the helium pressure regulator using the regulator adjustment screw and set the discharge
pressure to the desired setting (100–600 psi). The pressure to the system is indicated by the low
pressure gauge on the regulator. Do not set the discharge pressure above 600 psi; the helium
regulator has an over-pressure relief valve that will vent the system at 700 ± 50 psi. Additionally, the
regulator is self-venting: turning the the regulator adjustment screw counterclockwise will reduce
pressure to the system.
4. Put on hearing and eye protection, point the device away from any bystanders, and depress the trigger
2–3 times to discharge the device as described below. If this step is performed without a cylinder in
place, the O-rings may be blown out.
Fig. 16. Position of hand over the safety interlock switch in preparation for firing.
Section 5 Operation of the Helios Gene Gun System
Helios Gene Gun System | 29