User Supplied Components - BIO RAD Helios Gene Gun System Instruction Manual

Section 2 Introduction to Particle Delivery

User Supplied Components

Helium Supply
Only helium gas is to be used with the Helios Gene Gun. The low atomic weight of helium results in
maximum gas expansion when the high-pressure helium is released through the valve opening and enters
the cartridge at atmospheric pressure. Thus, sufficient acceleration of the DNA-coated microcarriers is
generated for penetration of the target cell membrane.
Compressed helium of grade 4.5 (99.995%) or higher should be used; lower grades may contain
contaminating material, which can obstruct gas flow within the Helios Gene Gun as well as contaminate the
biological sample. A helium tank pressurized to 2,600 psi (approximately 5 ft (1.7 m) high, 291 cu ft standard
in the U.S.) is recommended, although a smaller tank (~2.5 ft (~0.8 m) high) may be used. Follow all safety
instructions provided by the helium supplier for helium tank installation.
The helium pressure regulator (supplied) has a CGA 580 female fitting (standard in the U.S.) for attachment
to the user-supplied helium tank. An adaptor to this fitting may be required outside of the U.S. Contact
your local Bio-Rad office for information on the helium pressure regulator adaptor requirements in your
location. The regulator supplied with the Helios Gene Gun is the only one that should be used with this
instrument because of its three safety features: (1) a self-venting valve that permits decreasing the pressure
in the Helios Gene Gun System in the event of battery failure or when it is necessary to reduce the pressure
during an experiment; (2) an over-pressure relief valve that prevents the helium pressure in the Helios Gene
Gun System from being adjusted above 700 psi ± 10%; and (3) a check valve that shuts off pressure if the
helium hose is disconnected while the system is still pressurized (Note: a check valve is also present at the
female connector of the helium hose where it connects to the gene gun to shut off pressure to the gun if it
is disconnected while the system is still pressurized.) Refer to Connecting the Helios Gene Gun to a Helium
in Section 4 for proper use of the helium regulator and to Removing Used Cartridges, Depressurization, and
Shutdown in Section 5 for a description on shutting down the gene gun system.
A user supplied 10" or 12" (~25 cm) adjustable wrench or a 1 1/8" open end wrench is required for attaching
the helium regulator to the helium tank.
Nitrogen Supply
Compressed nitrogen of grade 4.8 (99.998%) or higher is required for cartridge preparation using the Tubing
Prep Station. Nitrogen is used for this purpose because it is relatively inexpensive and provides a water-free
atmosphere for evaporating the ethanol from the DNA/gold sample inside the tubing. As with the helium
tank, the nitrogen tank should be properly secured on a floor stand or with a strap for safety.
A nitrogen regulator must be attached to the tank. A single-stage regulator with an output gauge that
registers a maximum of 30 psi is recommended since an output pressure of no more than 1–2 psi is needed
to produce the 0.4 liters per minute (LPM) flow rate necessary for using the Tubing Prep Station. A regulator
especially designed for this use, including a self-venting valve, an over-pressure relief valve, and a hose barb
for attaching the nitrogen hose, is available from Bio-Rad (#1652425). Other regulators that are adjustable
to give a low pressure output may also be used. Manufacturers of regulators include Victor and Matheson;
examples of regulators that may be used include Victor Model No. SR250A-580 and Matheson Model No.
3537-580. Large scientific supply houses (for example, VWR, Fisher Scientific, CMS, etc.) are also good
sources for regulators. The nitrogen line provided for use with the Cartridge Prep Unit is 3/16" diameter
Tygon Tubing.
6 | Helios Gene Gun System