Instruction Manual

Troubleshooting 47
Table 5-2 Troubleshooting, Premature Stopcock Failure
Symptom Possible Cause Recovery
A. Pressure is too high in the
pump chamber, or pressure
exceeds recommended
settings.
A. Reduce dispensing pressure
by one of the following
methods:
1. Reduce dispense needle
length; increase needle ID;
or change to cone needle.
(Needle size and type
effects pressure).
2. Reduce dispense rate
(flow rate), see Table 5-6
for recommended rates.
3. Decrease fluid viscosity by
applying needle heat.*
4. Reduce fluid viscosity by
adjusting fluid formulation
(retain same chemistry
only change viscosity).
12. Stopcock is cracked or
leaking. Evidence of
dispensing drooling or
tailing (air in chamber).
(After 3 to 12 hours of
production)
B. Fluid and stopcock chemical
incompatibility (usually
solvents**).
B. Change solvents or change
the disposable stopcock
(Nylon or Polycarbonate) as
follows:
1. Replace Stopcock
42-0080 with Stopcock
42-0367 or 42-0083***.
2. Avoid leaving dispensing
fluid in the system after
shutdown or overnight.
3. Do not use excessive
solvents when cleaning
and allow to air-dry
immediately.
* Most encapsulants can be locally heated near the needle without adversely affecting fluid pot life. If a fluid
has a limited pot life, the increase in viscosity can cause premature failure. Most fluid pot life ratings are
based on a 100% increase in viscosity (if a fluid is given pot life of 24 hrs at a given temperature, the
viscosity and dispense pressure will double in 24 hrs).
** Isopropyl Alcohol, MEK, and Acetone can harm stopcock 42-0083. Note that flow restriction is higher and
may limit refill speed when using 42-0083. A different syringe or cartridge clip may be needed as the
alignment of the fitting changes slightly. See Table 5-5.
*** Depending on dispensing fluid, select the Nylon 42-0083 stopcock or Polycarbonate 42-0367 stopcock as
appropriate.