Determining Proper Fluid Temperature - Graco VISCON HP 309524L Instructions Manual

Installation
Determining Proper Fluid
Temperature
CAUTION
Operating the heater at its highest setting, over 180°F
(82°C), for long periods of time decreases the heater
life and can cause fluid to dry out; which can clog the
heater and result in a poor finish.
Use the lowest temperature setting possible for maxi-
mum heater life. Use the chart in F
®
Under-Boil temperature. F
temperature on reducing viscosity. Note that most of the
viscosity reduction occurs by 130°F (55°C).
Under-Boil is the Graco method of hot, airless spraying
where the fluid is heated to a temperature just under the
boiling point of its most volatile solvent.
100
90
80
70
60
50
40
30
20
10
0
20
(70)
F . 9: Reducing Viscosity: Under-Boil Method
IG
12
. 9 to determine the
IG
. 9 also shows the effect of
IG
30 40
(80) (90) (100) (110)
To find your fluid's Under-Boil temperature:
1. Pour a small sample into a heat-proof container.
2. Measure and record the fluid temperature and vis-
cosity using a No. 2 Zahn cup.
3. Heat water in a large container to 200°F (93°C).
Place the sample in the water.
4. At every 10° temperature rise, measure and record
the viscosity and temperature. Do this until solvents
start boiling off and the viscosity starts to level off,
usually 160-170°F (71-77°C).
5. To find the temperature to use in your Under-Boil
system:
a. Subtract the lowest viscosity reading from the
highest one.
b. Multiply the result by 0.90.
c. Subtract the result from the highest viscosity
reading. Find this number on your temperature
and viscosity records.
Heavy Lacquer
Medium Lacquer
Enamel
50 60
(120) (130) (140) (150)
Temperature
o
70 80
C
(160) (170) (180) o
( F)
309524L