Graco Optimiser 02017 Instructions Manual page 6

CHART 3: OPTIONAL ORIFICE PURGE
SST NEEDLE
Optional
Stainless Steel
Orifice-Purge
Needle Part No.
186–931
186–932
186–933
186–934
Use these needles to purge fluid out of the nozzle
orifice to prevent plugging of the tip with fast drying
material. A needle shaft assembly (part no.
224–849) must be used with these needles and
replaces the standard one-piece needles.
Selecting the Proper Needle/Nozzle/Air
Cap Set
The High Volume Low Pressure Spray Gun's needle/
nozzle sets range in size to provide different fluid flow
rates. Chart 1 shows the recommended combinations
based on fluid viscosities and flow rates.
As a general guideline, use the fluid nozzle that will
give the required flow with the needle fully triggered at
the lowest fluid pressure.
For low flow rates or light viscosity fluid, select the
smaller nozzle sizes.
For high flow rates or high viscosity fluid, select the
larger nozzle sizes.
Using an air cap size that is smaller than the nozzle/
needle size is not recommended.
NOTE: To help select the proper needle/nozzle size, a
fluid pressure gauge may be connected temporarily to
the gun fluid inlet to determine the fluid pressure. See
Accessories.
6 308–293
Selection Charts
Orifice Size
0.042" (1.067 mm)
0.055" (1.397 mm)
0.070" (1.778 mm)
0.086" (2.184 mm)
CHART 4: NEEDLE ASSEMBLY
REPLACEMENT TIPS
Needle Assembly
Part No.
238–217
238–218
238–219
238–703
Selection Problems and Solutions
PROBLEM POSSIBLE
CAUSE
Fluid pressure is too Using set with
high (greater than too small orifice
10 psi [70 kPa, 0.7
bar]) with gun trig-
gered
Using a low pres- Using set with
sure setting, the too large orifice
fluid flow is too high,
making it necessary
to restrict needle
travel to reduce fluid
flow.
Fluid system will not There's no fluid
operate at low regulator or air
enough fluid pres- regulator is not
sure [below 10 psi sensitive
(70 kPa, 0.7 bar)] enough
Needle Tip P/N
191–016
191–017
191–018
191–564
SOLUTION
Use needle/
nozzle/air cap
set with larger
orifice
Use needle/
nozzle/air cap
set with small-
er orifice
Add low pres-
sure fluid regu-
lator or add
more sensitive
air regulator on
pressure pot