Pressure Pot-Priming the spray gun

[tjbnwi]

Again, I apply the word bleeding to a closed system, purging to an open system.

This is a war or a choice of words.

Your backpack rigged to the Fuji----where did you connect the backpack return line on the Fuji gun? There is no device on the Fuji to allow you to to prime/bleed the Fuji. So how did you make it work with the Fuji gun? (these are rhetorical questions)

That return line wasn't used and was plugged on the backpack tank.  It then became a generic pressure pot.  I'd start the battery pump only, pull the trigger and the material travels up the line.  When the material reaches the fitting on the Fiji gun, I start the turbine and a second later test the pattern.

If one doesn't press the trigger, you are trying to force liquid into a closed line or system, correct?  Does pressing the trigger make it an open system?  By pressing the trigger, you allow air to be forced out, correct?  I'm avoiding to use of bleed or purge, our problem terms here.

The backpack---is the pump a small air compressor that pressurizes the tank or a fluid transfer pump that pressurizes the fluid that enters it to move it down line?
Was the return line in use when spraying or just when you primed the pump?
(I've never seen or used the backpack, curious as to how it functions)

Not trying to do anything, just making the system ready for use.

It's an open system, the system is designed to have the product/fluid exit the system. A closed system is designed so the product/fluid des not leave the system durning normal use.

Tom

 

[tjbnwi]

I don't believe the turbine provides enough pressure to move heavy viscosity waterbourne coatings through the fluid line to the gun so I use a compressor driven pressure pot system. Without the help of gravity (gravity gun) or siphon (bernoulli siphon) the pressure from a turbine is not sufficient to adequately move heavier viscosity coatings through a fluid line.

Rethinking this again.  The viscosity of the material is set or determined by the gun.  Does it really matter if you can pump molasses up to the gun which can't spray it?

Fuji suggests a Q4 or Q5 for its pressure pot.  Pressure pots have a material line length limit as well as there is a pressure drop.  Just like turbines have a line length limit also.  This also changes if you are working off a ladder.

The gun does not determine the material viscosity. There are many factors that determine the viscosity, the gun is not one of them.

The viscosity will determine which gun/set up used. Matching the equipment to the product is the key. I've sprayed materials with a Ford 4 of over 4-1/2 minutes with my T-70. I have serviced Graco equipment that spray products thicker than molasses.

I've run 75' of fluid hose on my pressure pot, adjust the pressure in the pot to make up for friction loss in the hose. That is the advantage to a stand alone pot, the air pressure is not limited to the turbine pressure (the pot I own the limit is 65 psi).

Tom

 

[tiralie]

The viscosity of the material is set or determined by the gun.

Not correct. All things being equal (local regulations etc.) the setup dictates what you can spray. Perhaps this is what you meant.

Fuji suggests a Q4 or Q5 for its pressure pot.  Pressure pots have a material line length limit as well as there is a pressure drop.  Just like turbines have a line length limit also.  This also changes if you are working off a ladder.

A turbine  generates pressure as a result of volume of air forced through the line. It does not operate the same as compressor. When the line is extended the area is increased, the air flow is spread out over a greater area and therefore a drop in pressure. When there is no air flow there is very little pressure in a turbine line as the turbine does not contain any valves and cannot hold any pressure in the line. When there is too much pressure in the line as a result of blockage etc. and no bleed, the motor slows down as the volume of air in the line is equal to the energy it takes to exceed that threshold. I am sure there is a limit to the line length but for our purposes I doubt we would need it.

There is a pressure drop in all pressure pots whenever you squeeze the trigger on the gun but the compressor will kick in and pressurize the pot. It is true that the longer a fluid line the more entropy there is but as Tom states, that can be compensated for by more energy in the form of higher compression in the tank.

Tim

 

[wptski]

The gun does not determine the material viscosity. There are many factors that determine the viscosity, the gun is not one of them.

The viscosity will determine which gun/set up used. Matching the equipment to the product is the key. I've sprayed materials with a Ford 4 of over 4-1/2 minutes with my T-70. I have serviced Graco equipment that spray products thicker than molasses.

I've run 75' of fluid hose on my pressure pot, adjust the pressure in the pot to make up for friction loss in the hose. That is the advantage to a stand alone pot, the air pressure is not limited to the turbine pressure (the pot I own the limit is 65 psi).

I worded incorrectly.  The gun determines the viscosity it can use as there's the chart with all the times for a #4 Ford cup and that's what I meant.  Maybe you guys don't follow any viscosity guidelines?  Being a relatively new to this, I try to.

How did all this heavy viscosity material spray, finish wise or didn't that matter?  There are some materials that don't!

All I need is a gauge/regulator to convert the Fuji to a non-turbine pot and I already have that if needed.  From the looks of it, it's C.A.T. pot modified for Fuji marked for 50psi max.

 

[wptski]

A turbine  generates pressure as a result of volume of air forced through the line. It does not operate the same as compressor. When the line is extended the area is increased, the air flow is spread out over a greater area and therefore a drop in pressure. When there is no air flow there is very little pressure in a turbine line as the turbine does not contain any valves and cannot hold any pressure in the line. When there is too much pressure in the line as a result of blockage etc. and no bleed, the motor slows down as the volume of air in the line is equal to the energy it takes to exceed that threshold. I am sure there is a limit to the line length but for our purposes I doubt we would need it.

There is a pressure drop in all pressure pots whenever you squeeze the trigger on the gun but the compressor will kick in and pressurize the pot. It is true that the longer a fluid line the more entropy there is but as Tom states, that can be compensated for by more energy in the form of higher compression in the tank.

The turbine has no tank like a compressor does.  To my knowledge the turbine motor doesn't slow down.  When you release the gun trigger it dumps pressure through a valve that the tone change that you hear.

It appears not to be a valve but an added hole it states here.

 

[tjbnwi]

The gun does not determine the material viscosity. There are many factors that determine the viscosity, the gun is not one of them.

The viscosity will determine which gun/set up used. Matching the equipment to the product is the key. I've sprayed materials with a Ford 4 of over 4-1/2 minutes with my T-70. I have serviced Graco equipment that spray products thicker than molasses.

I've run 75' of fluid hose on my pressure pot, adjust the pressure in the pot to make up for friction loss in the hose. That is the advantage to a stand alone pot, the air pressure is not limited to the turbine pressure (the pot I own the limit is 65 psi).

I worded incorrectly.  The gun determines the viscosity it can use as there's the chart with all the times for a #4 Ford cup and that's what I meant.  Maybe you guys don't follow any viscosity guidelines?  Being a relatively new to this, I try to.

How did all this heavy viscosity material spray, finish wise or didn't that matter?  There are some materials that don't!

All I need is a gauge/regulator to convert the Fuji to a non-turbine pot and I already have that if needed.  From the looks of it, it's C.A.T. pot modified for Fuji marked for 50psi max.

If I spray it, it matters.

The chart in the manual is a guideline. If I recall correctly there is not a temperature adjustment column in the chart. Temperature has a very big affect on viscosity. There are times I'll place the can of product in hot water prior to spraying. I had one job where I had a heater directed at the pressure pot an entire job 75 gallon job.

These are all 4+ minute paints. The last one is SW Super Paint with KA+ BRE over it. All shot with the Q4/T-70/Gxpc/PPS -- the pressure pot was not used on any of these.

You'll learn to adjust for the paint, temperature and equipment.

Tom

 

[wptski]

If I spray it, it matters.

The chart in the manual is a guideline. If I recall correctly there is not a temperature adjustment column in the chart. Temperature has a very big affect on viscosity. There are times I'll place the can of product in hot water prior to spraying. I had one job where I had a heater directed at the pressure pot an entire job 75 gallon job.

These are all 4+ minute paints. The last one is SW Super Paint with KA+ BRE over it. All shot with the Q4/T-70/Gxpc/PPS -- the pressure pot was not used on any of these.

You'll learn to adjust for the paint, temperature and equipment.

A 75 gallon job!  I don't have enough miles left on my odometer to spray that much.

If you didn't thin the 4+ minute paints, what/when do you thin?

 

[tjbnwi]

If I spray it, it matters.

The chart in the manual is a guideline. If I recall correctly there is not a temperature adjustment column in the chart. Temperature has a very big affect on viscosity. There are times I'll place the can of product in hot water prior to spraying. I had one job where I had a heater directed at the pressure pot an entire job 75 gallon job.

These are all 4+ minute paints. The last one is SW Super Paint with KA+ BRE over it. All shot with the Q4/T-70/Gxpc/PPS -- the pressure pot was not used on any of these.

You'll learn to adjust for the paint, temperature and equipment.

A 75 gallon job!  I don't have enough miles left on my odometer to spray that much.

If you didn't thin the 4+ minute paints, what/when do you thin?

What, when and with what is situation dependent.

I also have all the air cap assemblies form guns.

Tom

 

[Scott B.]

This spraying thing sounds like a pain in the neck.

 

[tjbnwi]

This spraying thing sounds like a pain in the neck.

Only if you make it that way. [big grin]

Tom

 

[tiralie]

The turbine has no tank like a compressor does.

Not sure what you mean here. I did not state that the HVLP turbine has a compressor.

It appears not to be a valve but an added hole it states here.

Interesting, a very simple solution.
Thanks for finding this.
I checked and yes, there is a hole in the manifold of my Q4Gold for venting air when the gun trigger is not depressed. The hole in the manifold is inside the case. I would think there would be some loss of air flow and pressure during spraying.
Also interesting to note that my Fuji Q4 has a 4 stage Lamb tangential bypass motor that is fitted with an additional fan for cooling.
Tim

 

[wptski]

Not sure what you mean here. I did not state that the HVLP turbine has a compressor.

Interesting, a very simple solution.
Thanks for finding this.
I checked and yes, there is a hole in the manifold of my Q4Gold for venting air when the gun trigger is not depressed. The hole in the manifold is inside the case. I would think there would be some loss of air flow and pressure during spraying.
Also interesting to note that my Fuji Q4 has a 4 stage Lamb tangential bypass motor that is fitted with an additional fan for cooling.
Tim

Correct, you never stated that it had a tank.  No tank, it just can't keep on running when the trigger is released for long periods possibly or it would overheat, etc. hence the hole not a valve to solve the problem.

I've read that a turbine isn't designed to be leak free, leaks are no problem for a turbine.  I know most fittings on Fuji Gxpc are straight threads, no "O" rings, etc. to seal.  I've seen bubbles come from mine when they are wet.

I had made a new fitting on my two Gxpc's where the pressure tube connects with a push to connect fitting with an "O" ring under the hex head to seal tight but I guess that was overkill.

 

[brewster201]

I was a little curious so I checked my Fuji Super4 Gold up. I was a little disappointed, just a bleed off hole on the discharge.

I thought there would be some kind of springloaded poppet valve to blow off air when there was no load

 

[tjbnwi]

This is why I don't bother looking at the inner workings unless theres a problem.

Speaking of problems-----I was spraying today and things were not sounding right off the gun. I hadn't change the turbine filter in awhile. That was it, biggest problem is I'm out of them. Had to clean it to finish the job. Time to order 6 more.

Tom

 

[wptski]

This is why I don't bother looking at the inner workings unless theres a problem.

Speaking of problems-----I was spraying today and things were not sounding right off the gun. I hadn't change the turbine filter in awhile. That was it, biggest problem is I'm out of them. Had to clean it to finish the job. Time to order 6 more.

Tom

That's why curious minds tend to get confused! :

 

[tjbnwi]

This is why I don't bother looking at the inner workings unless theres a problem.

Speaking of problems-----I was spraying today and things were not sounding right off the gun. I hadn't change the turbine filter in awhile. That was it, biggest problem is I'm out of them. Had to clean it to finish the job. Time to order 6 more.

Tom

That's why curious minds tend to get confused! :

I'm always curious, have learned to curb it until necessary---a product of old age.

Tom

 

[Scott B.]

I'm curious.

And generally confused too.

 

[brewster201]

I'm glad to be retired lol

Not spraying till the warmer weather [smile]

 

[wptski]

Do these compressor powered pressure pot even cycle the compressor once the material is pressurized?  That air isn't consumed like what's supplied to the gun so the maximum volume air only needs to be the size of the pot.  I assume there is a check valve to hold the pressure within the pot.  It seems that a small air storage tank would be enough to keep a pressure pot pressurized.

 

[tjbnwi]

Yes, the compressor will cycle. Air pressure drops in the pot as the fluid is displaced. The Jc-10 will cycle every 4 minutes or so on my 2.5 gallon pot.

No check valve on the inlet of my pot.

Tom