Biomedical Engineering Reference
In-Depth Information
The opening time of solenoid valves suitable for this application is 15 ms
minimum, thereby throttling the flow in the barrel as the particle is
accelerated. To avoid this throttling effect, valves with opening times
significantly less than 5 ms were sought. As mentioned in the previous section,
fast valves are used in nuclear fusion research and development devices. An
example of one such valve is illustrated in Figure 12 and Figure 13. This type
of valves operates with a solenoid coil activated by a capacitive discharge
circuit (Combs, Foust, and Gouge, 2004). Opening time is calculated to be
approximately 2 ms for this valve; a possibility for the application in this
study.
A similar type of valve, also electromagnetic, is presented in Figure 14.
The claimed opening time for this valve ranges from 20 - 800 µs (Shen et al.,
1994).
Reproduced with permission. Copyright retained by Inderscience Publishers.
Figure 14. Fast acting valve (Shen et al., 1994).
A different type of valve researched is the burst disc type valve, also
known as a diaphragm gas valve. This type of valve is commonly used as a
safety device to relieve pressure on compressed gas tanks, to avoid the
bursting of the tank in the event that pressure is increased beyond a desired
level. Through literature searches, it has also been found that this type of valve
has also been used to fire projectiles; such is the case with pneumatic guns
developed by NASA to study impacts of large projectiles, to simulate the
striking of debris at high speed. There are three such guns of varying sizes at
the NASA ballistic impact facility. The large gas gun utilizes a Mylar burst
disc to fire its projectile, with the burst disc portion shown in Figure 15. This
