Datascope System 98 Service Manual page 164

e Fill System
The [AB is inflated and deflated by shuttling a predetermined volume of fill gas
into and out of the IAB. Preloading the shuttle gas system with a predefined
volume of Helium is the function of the fill system.
A fill cycle begins by purging the shuttle gas system (IAB, catheter extender and
Safety Disk. This is accomplished by activating the purge solenoids (K3 and K5),
allowing the Safety Disk diaphragm to move to the patient side of the disk. The
isolation valve (K4), and the Fill valve (K2) are activated to insure the volume cyl-
inder is empty. After it has been determined that the volume cylinder is empty,
K4 and K2 are deactivated. To allow the Safety Disk diaphragm to move to the
patient side of the Disk, KG is activated, venting the residual vacuum in che drive
side to atmosphere. Purging continues until the shuttle gas pressure
attains the first surveillance level. A leak in the shuttle gas system will cause the
pressure to rise. Therefore the shuttle gas pressure is observed for a short period of
time. If a rise in pressure is detected, surveillance continues, otherwise the purge
is resumed until a second surveillance level is attained. Once again the shuttle gas
is examined to flag any rise in pressure. Two surveillance levels are required to
detect large and small leaks. By applying a greater differential pressure across the
IAB membrane, smaller leaks can be detected. If no leaks were detected, the
purge process continues.
While the shuttle gas system is being purged, the volume cylinder is filled with
Helium. This is accomplished by activating the Helium solenoid (K1). K1
remains active for a timed interval after the (S1) is tripped. Deactivation of K1
vents the pressure in the volume cylinder to atmosphere. This action equalizes the
helium in the volume cylinder to local atmospheric pressure. Once the purge and
the volume cylinder filling are complete, vacuum is once again applied to the
Safety Disk drive by activating K6A, and ,K7. Activation of the fill solenoid (K2)
and isolation solenoid (K4) then connects the volume cylinder to the shuttle gas
system. Vacuum in the shuttle gas system draws the charge of helium from the
volume cylinder. Once che volume cylinder plunger returns to the empty
position, as determined via activation of the Empty sensor (S2), the fill is
complete, K2 & K4 are de-activated, completing the autofill process.
To maintain helium purity in the shuctle gas circuit the AUTOFILL process 1s
repeated at 2 hour intervals when the FILL mode is in AUTO.
9 Blood Back Detection
The presence of blood is detected by its absorption of green light. Once blood is
detected, the valves K3 and KS are closed, which blocks any further flow into the
system.
» Condensate Removal
The condensate removal module is an integral part of a Safety Disk assembly.
During IAB therapy, to prevent water from condensing in the catheter, the
shuttle gas must be dehumidified. This is done with a cold trap attached ro the
Safety Disk. The cold trap uses a thermo-electric cooler (Peltier) to pump heat
from the trap to a small fan cooled hear sink.
The temperature of the cold trap is below the dew point, consequently the water
vapor condenses and collects in the trap. The collected water is removed during
the purge portion of the fill cycle.
2-52 System 98 Service Manual
Chapter 2, Theory of Operation