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Mel Skerpon Posted: Jan 08, 2008 03:43 PM	Problems with whip We have had 2 whips block up (iso side) in the past two weeks. Both times right after a drum change. Demilac suggested air in the line from running the drum dry. We have been running this way for the past 2.5 years with no problems. Anyway, the crossover occured 2 pump cycles into the new drum both times. Gun is GapPro with a #3 mixing chamber. Using HV 20/35.
mason Posted: Jan 08, 2008 03:53 PM	It is not easy to trouble shoot equipment without being there and observing the operation and condition of the rig. But my advice is not to assume that one thing is causing the crossover just yet. Many factors can cause a cross over. It could be related to the drum pump, cold material, clogged filter, check balls not seated properly or other proportioner pump problem causing cavitation. Or it could be a problem with the gun or hoses. It may be just a coincidence that it happens when you switch material or related to another element of your shut down and start up procedure. I would start from scratch, run material through your hoses with the pumps running and the gun off to get any air out of the lines, (save your material) You will need to run it a while to get all the material through the line. Check your material flow on both sides of the hoses for pressure and volume of material (catch the material in two clean buckets and observe if one has more liquid than the other). Cavitation will show on one side on the pressure guages as low pressure pulses, corresponding to high pressure pulses on the other. Check that the drum pumps are are time with each other. If one is taking two strokes to one of the other or if one stops for a moment and then catches up you may to check your drum pumps for problems (such as the ball not seating properly or getting stuck initially or cold material on one side. If there is no imbalance of pressure or inadequate flow on one side, then the problem is in your gun or hose or whip. Another question, do you shut your proportioner off before switching drums or try to do it while it is running? The latter technique can introduce air into the lines. Shut the proportioner down, take the air lines off the tranfer pump before switching drums. Then attach the air lines and turn the proportioner back on. I try not to run my drums dry and instead change them when there is still some liquid left. Then pour up the drums at the end of the day. This keeps the drum pumps from pumping dry and sending air into the proportioner.
Michael Flander Posted: Jan 09, 2008 10:30 AM	Is the "A" side of the gun crossing over also? If it is not, you can eliminate the gun from the equation. For the gun to be the problem it would have to start at the mix chamber and work its way back to the hose through the check valve, which happens, but your gun will be blocked up also... Foam can also make its way through the air purge passages... but that doesn't sound like your problem. If your gun is also blocked up... you found your problem. This could certainly be caused by running a barrel dry. Air in the system could cause random pressure drop on one side and cavitation as Mason stated above.
Mel Skerpon Posted: Jan 10, 2008 11:46 AM	We think we may have determined the source of the problem. We operated almost 2 years without a crossover. Around a 1.5 months ago we sampled a soy based product which used Lupranate M20S Iso. Up to that point we were using Sealection 500 exclusively. We think that there may be a partial blockage on the iso line somewhere. This morning, we had a crossover on the first cycle. Our theory is that going from a ambient temperature to full hose heat and pressure is causing the partial blockage to shed particles cloging the iso side and causing the crossover. this morning after clearing the gun we were spraying normally. My questions are this, (1) could there have been an incompatibly with the iso. My understanding is that everyone uses the same product(maybe a different manufacturer)? and (2) Is there any way to flush an iso line, solvent?? Thank you for your input
mason Posted: Jan 10, 2008 03:41 PM	There are subtle differences between types of Iso. All Iso can get contaminated by high humidity or condensation in the drum or lines, But some Iso sets up hard with tiny crystals) and some set up somewhat softer (like gum or jelly) I have had little success flushing out Iso lines. But, if the iso is soft & gummy in your lines and not hard crystals you might get lucky by flushing the line with TCP or another plasticizer. Then leave it in the lines for a few days. Sometimes this softens the iso enough for fresh material to flow through it. If there are hard crystals, they won't stop and will probably get worse over time. PS don't reuse the flushed Iso material. As always, Check with your supplier for their specific recommendations.
Gerry Wagoner Posted: Jan 10, 2008 08:26 PM	This is why we use a Filtration Systems filter assembly on our spray rig. Easier to replace a 4 x 14' bag once a year than to experience hose/gun problems. oG
Posted: Jan 10, 2008 10:48 PM	Olger, can you 'splain that filtration system?
Mel Skerpon Posted: Jan 11, 2008 11:21 AM	Olger, Which Filtration Systems product do you use and where in the line do you place it? Thank You for your input.

Author

Comments

Mel Skerpon

Posted: Jan 08, 2008 03:43 PM

Problems with whip

We have had 2 whips block up (iso side) in the past two weeks. Both times right after a drum change. Demilac suggested air in the line from running the drum dry. We have been running this way for the past 2.5 years with no problems. Anyway, the crossover occured 2 pump cycles into the new drum both times. Gun is GapPro with a #3
mixing chamber. Using HV 20/35.

mason

Posted: Jan 08, 2008 03:53 PM

It is not easy to trouble shoot equipment without being there and observing the operation and condition of the rig. But my advice is not to assume that one thing is causing the crossover just yet. Many factors can cause a cross over. It could be related to the drum pump, cold material, clogged filter, check balls not seated properly or other proportioner pump problem causing cavitation. Or it could be a problem with the gun or hoses.

It may be just a coincidence that it happens when you switch material or related to another element of your shut down and start up procedure.

I would start from scratch, run material through your hoses with the pumps running and the gun off to get any air out of the lines, (save your material) You will need to run it a while to get all the material through the line. Check your material flow on both sides of the hoses for pressure and volume of material (catch the material in two clean buckets and observe if one has more liquid than the other).

Cavitation will show on one side on the pressure guages as low pressure pulses, corresponding to high pressure pulses on the other. Check that the drum pumps are are time with each other. If one is taking two strokes to one of the other or if one stops for a moment and then catches up you may to check your drum pumps for problems (such as the ball not seating properly or getting stuck initially or cold material on one side.

If there is no imbalance of pressure or inadequate flow on one side, then the problem is in your gun or hose or whip.

Another question, do you shut your proportioner off before switching drums or try to do it while it is running? The latter technique can introduce air into the lines. Shut the proportioner down, take the air lines off the tranfer pump before switching drums. Then attach the air lines and turn the proportioner back on.

I try not to run my drums dry and instead change them when there is still some liquid left. Then pour up the drums at the end of the day. This keeps the drum pumps from pumping dry and sending air into the proportioner.

Michael Flander

Posted: Jan 09, 2008 10:30 AM

Is the "A" side of the gun crossing over also? If it is not, you can eliminate the gun from the equation. For the gun to be the problem it would have to start at the mix chamber and work its way back to the hose through the check valve, which happens, but your gun will be blocked up also...

Foam can also make its way through the air purge passages... but that doesn't sound like your problem.

If your gun is also blocked up... you found your problem. This could certainly be caused by running a barrel dry. Air in the system could cause random pressure drop on one side and cavitation as Mason stated above.

Mel Skerpon

Posted: Jan 10, 2008 11:46 AM

We think we may have determined the source of the problem. We operated almost 2 years without a crossover. Around a 1.5 months ago we sampled a soy based product which used Lupranate M20S Iso. Up to that point we were using Sealection 500 exclusively. We think that there may be a partial blockage on the iso line somewhere. This morning, we had a crossover on the first cycle. Our theory is that going from a ambient temperature to full hose heat and pressure is causing the partial blockage to shed particles
cloging the iso side and causing the crossover.
this morning after clearing the gun we were spraying normally. My questions are this, (1) could there have been an incompatibly with the iso. My understanding is that everyone uses the same product(maybe a different manufacturer)? and
(2) Is there any way to flush an iso line, solvent?? Thank you for your input

mason

Posted: Jan 10, 2008 03:41 PM

There are subtle differences between types of Iso. All Iso can get contaminated by high humidity or condensation in the drum or lines,

But some Iso sets up hard with tiny crystals) and some set up somewhat softer (like gum or jelly)
I have had little success flushing out Iso lines. But, if the iso is soft & gummy in your lines and not hard crystals you might get lucky by flushing the line with TCP or another plasticizer. Then leave it in the lines for a few days. Sometimes this softens the iso enough for fresh material to flow through it. If there are hard crystals, they won't stop and will probably get worse over time.

PS don't reuse the flushed Iso material.

As always, Check with your supplier for their specific recommendations.

Gerry Wagoner

Posted: Jan 10, 2008 08:26 PM

This is why we use a Filtration Systems filter assembly on our spray rig. Easier to replace a 4 x 14' bag once a year than to experience hose/gun problems.

oG

Posted: Jan 10, 2008 10:48 PM

Olger, can you 'splain that filtration system?

Mel Skerpon

Posted: Jan 11, 2008 11:21 AM

Olger, Which Filtration Systems product do you use and where in the line do you place it? Thank
You for your input.

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