Bio-Rad PDS-1000 / He™ and Hepta™ Systems - Manual (Page 18)

3.2 Connecting the PDS-1000/He Unit to a Vacuum Source
The main unit is shipped with the vacuum hose assembly attached to the port on the rear
of the unit, via the clamping assembly. Only the connection of the free end of the tubing to a
vacuum source is required for connecting the vacuum source to the system.
Choice of Vacuum Source
A vacuum system with a 3 cfm (cubic feet per minute) or 100 l/min pumping capacity is rec-
ommended for use with the PDS-1000/He unit. This minimizes the total time the target cells/tis-
sue are exposed to reduced atmospheric pressure when inside the bombardment chamber. It is
also recommended that the pump have an exhaust mist eliminator.
House or shared source vacuum systems commonly have variable evacuation capacities,
from 20 inches to 23 inches Hg. When multiple users access a common vacuum system, the
actual vacuum pressure will vary, often decreasing to less than 20 inches Hg. per outlet. This
is an inadequate vacuum level for yeast and plant cell/tissue bombardment.
Most rotary vacuum pumps will achieve up to 26–28 inches of mercury (Hg) vacuum.
However, the length of time required to attain the desired vacuum depends on the pumping
capacity of the vacuum source. The higher the pumping capacity, the less time is required to
achieve the desired vacuum. Variation in evacuation time in the bombardment chamber has
an unknown effect on target cells and tissue transformation efficiency.
Table 3.2. Pumping rates of various vacuum systems with the
PDS-1000/He system
Vacuum Source Vacuum Level
Pumping Capacity (inches of Hg) Evacuation Time †
House/Common Source 20 10–15 seconds
29 Typically not attainable
Pump - 1 cfm or 28 l/min 20 12 seconds
29 45 seconds
Pump - 3 cfm or 100 l/min 20 7 seconds
29 25 seconds
† Vacuum Flow Rate Valve fully open.
Replacement and Re-assembly of connecting components
See Figure 3.2 for a diagram outlining component assembly. The clamp consists of an O-
ring and a vacuum hose centering ring with male nozzle fitting screwed to it.
1. Place the clamping assembly at one end of the vacuum tubing. The vacuum tubing is
PVC-reinforced Tygon tubing (1/2" ID x 3/4" OD; 5 feet length).
2. The vacuum tubing is shipped with the clamping ring assembly (Figure 3.2) attached to
the PDS-1000/He unit at the brass vacuum port located on the rear of the unit.
3. Attach the free end of the vacuum hose assembly to the vacuum source.
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