Volume Balancing The Mix Manifold - Graco XM PFP Instructions - Parts Manual

Volume Balancing the Mix
Manifold
Ratio errors can occur between the sprayer and the mix
manifold even when the sprayer output ratio is accurate.
The following can occur when the hoses are not volume
balanced to the mix ratio:
• Hoses fill to high pressure while metering on-ratio.
• Only the A material hose rises to spray pressure.
• Off-ratio at the mix point until hose pressures equal-
ize.
Lead/Lag Imbalance
When resin and hardener volume requirements (ratio)
and/or viscosities are different an imbalance can occur
each time the gun is triggered. This occurs because the
fluids can rush out of the manifold near a 1:1 ratio before
the sprayer starts.
To avoid this imbalance:
• Pressurize hoses to spray pressure before starting
spray mode.
• Size the fluid delivery hose volume to nearly match
the mix ratio. See Table 1.
3A2988C
Hose Selection
Hoses should be sized to match the hose volume ratio
to the mix ratio. The hose size should also allow for min-
imum pressure drop on the major volume side to meet
your flow requirements.
Use Table 1 to match mix ratio, hose selection, and vol-
ume ratio. Use Table 2 on page 14 to reference amount
of pressure drop for 50 ft lengths of different hose sizes.
Size hoses to:
• Minimize pressure drop on the high volume and
often higher viscosity resin side to achieve higher
flow and pressure at the gun while spraying.
• Allow both A and B material hoses to come up to
spray pressure together when A and B fluids are
metered into the hoses on ratio.
• Balance the inherent stall pressure between the
resin A and hardener B sides when the gun closes
and also when triggered. This reduces the lead/lag
error at the mix point when the spray gun is trig-
gered.
Table 1: Volume Ratio of A to B Hose
Hose
Selection
Mix Ratio A x B
1:1 3/4 x 3/4
1/2 x 1/2
3/8 x 3/8
2:1 3/4 x 1/2
1/2 x 3/8
3/8 x 1/4
3:1 3/4 x 1/2
3/8 x 1/4
4:1 to 6:1 1/2 x 1/4
4:1 to 8:1 3/4 x 3/8
6:1 to 10:1 1/2 x 3/16
8:1 to 10:1 3/4 x 1/4
Example: At a 4:1 mix ratio, a 1/2 in. ID resin hose and
a 1/4 in. ID hardener hose matches the 4:1 volume ratio.
Operation
Hose Volume
Ratio
1.00:1
2.25:1
1.78:1
2.25:1
2.25:1
2.25:1
4.00:1
4.00:1
7.00:1
8.80:1
13