Spray tests are used to fine-tune the adjustments on your MVP dispensing equipment and to check the condition of your hardware and materials.
Note: Using a color-reactive material (material that changes color when catalyzed) makes this testing easier to judge. MVP recommends using a dyed catalyst or a color-reactive material.
- Turn the chopper pressure to zero; you should do the spray test without the chop.
- Lay out a sheet of test material on a flat surface.
Note: The temperature of the surface can affect the reaction time of many chemicals and cause changes in cure times.
- Pull the trigger on the gun and begin spraying material along the test strip as shown in the figure below.
- When you hear the pump reverse direction, have an assistant mark the spot on the test strip and indicate whether the pump was at the top or bottom of the stroke.
- Continue spraying for four or five complete pump cycles and marking the stroke changes.
- Use a tongue depressor to test material hardening on several areas of the test strip, making sure to test the top and bottom of the stroke as well as the up and down stroke in several places.
- Repeat testing several times to determine if any areas are hardening faster or slower than others.
Note: Color-reactive materials will provide a visual indicator of material curing times as well, making this testing easy and accurate.
- Make notes to record what is occurring.
- Pay particular attention to any areas that harden faster or slower than others, indicating a problem.
Interpret Test Results
- If all areas of the test spray harden at the same time, skip to Performing Daily Tasks.
- If there are areas with little to no hardening or extremely fast hardening, use the following table to troubleshoot your problem.
|Material delivered at the top and bottom of the stroke is not curing or is curing more slowly than the material delivered in the middle of the up and down stroke, indicating low/no catalyst at the top and bottom of the stroke (see below).||There is no or improper accumulation effect in the catalyst system|
Note This is normally only a problem at high pressures
|Check to be sure you are using the proper catalyst hose, with or without core|
Install a catalyst accumulator, if needed
|Check for a restriction in the catalyst system|
|Material delivered at the top and bottom of the stroke is hot (curing very rapidly). Also, thin areas of material may be noticeable compared to the volume in the middle of the stroke, indicating low resin at the top and bottom of the stroke (see above).||There is no or improper accumulation effect in the resin system.|
Clean resin filter and reinstall.
|Resin accumulator full of hard material or blockage||Clean resin filter and reinstall or replace accumulator|
|Incorrect accumulator installed||Replace accumulator|
|Pump pressure is too high||Lower resin pump pressure|
|Material delivered on the catalyst pump up-stroke (from the bottom to the top) is not curing or slow cure, indicating that no catalyst is being delivered on the up-stroke (see below).||Worn or damaged catalyst piston seal||Replace worn or damaged parts. Refer to the catalyst pump service and repair manual.|
|Damaged catalyst pump cylinder|
|Worn or damaged piston body ball|
|Damaged piston body ball seat|
|Material delivered on the catalyst pump down-stroke (from the top to the bottom) is not curing or slow cure, indicating no catalyst is being delivered on the down-stroke (see above).|
Worn or damaged inlet body
|Replace worn or damaged parts. Refer to the catalyst pump service and repair manual.|
Worn or damaged inlet body ball
|Material is delivered with streaks running the length of the test spray. Some strips cure normally, some not at all, others cure at faster or slower rates (see below). This is not a pumping problem, it indicates a mixing problem when the fan is delivering streams of poorly catalyzed resin and/or pure catalyst.||The turbulent mixer is worn, clogged, or damaged in some way.||Shut down the system and inspect the turbulent mixer and mix chamber, then repair or replace parts as needed.|
|The mix chamber is scratched or damaged|
|Material delivered at the beginning of the test strip is hot (low in resin), followed immediately by material that is cold (low in catalyst), followed by material that is poorly mixed and cures (see below). This indicates that the system is unbalanced at the beginning of the spray. After a moment the system balances and properly mixed material is delivered.||The catalyst needle on the gun opens before the resin needle.||Adjust the catalyst and resin needles to the proper setting.|
|The catalyst gets through the gun before the resin||Adjust the gun that the resin comes out of the gun before the catalyst|
|Material delivered at the beginning of the test spray is cold (low catalyst), followed by material that is properly mixed and cures (see below). This indicates that the system is unbalanced at the beginning of the spray.||The resin needle is opening too soon before the catalyst needle, resulting in a shot of pure uncatalyzed resin until the catalyst needle opens.||Adjust the catalyst and resin needles to the proper setting.|
|The resin comes much earlier than the catalyst||Adjust the gun that resin comes a fraction ahead of the catalyst|