Restricting flow

[BrokenBiker]

I am trying to make my own version of a grease spray gun, for spraying EP type grease onto crane booms. They are available, but expensive, and I am loosely copying one I have used before, but doing so from memory pretty much.

I prototyped with a mish-mash of lube guns, air fed oilers and what not and it wants to work, but it's too sloppy of an attempt to get where it needs to be, but it has served it's purpose of showing me where the failures are.

So, I've got some ally on the way, some nice quality speed fittings, nylon pipe and a new spray head with a better trigger.

Stumbling block now though is that, while I need an air feed to the bottom of the grease cartridge, and an air feed to the trigger of the spray head, I need the feed to the trigger to be at a lower pressure to that of the grease cartridge.

This is all done via a T piece feeding the handle...I have 10 bar in the bottom through a 1/4 bap quick release, then a 4mm nylon pipe out the side to feed the bottom of the cartridge to force grease into the spray head, but I need a lower pressure in the spray head to allow the grease to actually be forced in. If the pressures matched, the grease won't move.

Am I right in thinking that if I put a smaller hole in the top of the T piece (the end that screws into the spray head and feeds the trigger) than the bore of the 4mm pipe feeding the cartridge, the cartridge pressure will still over power the pressure in the spray head and allow grease to be forced up while being sprayed out?

I am unsure if 4mm pipe is correct at the moment, but the joy of speed fittings is that the 4mm and 6mm both take an M6 hole, so upgrading later is as simple as changing 2 fittings and a bit of pipe and as I'm making the T piece myself, I can just bore the feed hole bigger to suit if needed to suit the upgrade.

This is all for my own personal use to save my back as currently doing this task stood on a ladder with a paint roller dipped in grease...rolling 48 meters worth of boom by hand is getting tiresome

 

[8ob]

Add heat

Bob

 

[BrokenBiker]

Add heat

Bob

I'm sure you are right...but how?

I don't see how heat could be useful?

 

[8ob]

I'm sure you are right...but how?

I don't see how heat could be useful?

Perhaps a small 12v heater element in the pot of something like a paraffin gun?

Bob

 

[Pete.]

Put a flow restrictor or pressure regulator on the feed to the canister then you can fine tune the setup. If you take the canister pressure as a bleed from the main air feed then the grease feed control would be automatic. Your problems would be over-feeding in summer and not feeding grease in winter.

 

[BrokenBiker]

Perhaps a small 12v heater element in the pot of something like a paraffin gun?

Bob

Oh right, no we can't do that. The grease needs to go on thick.

It also doesn't solve the issue of setting a ladder up 20 times and climbing it as many times then painting the grease over head...7.5 meter long sections, 5 sections to do.

Liebherr provide grease sprayers, but due to the cost I can't have one, and traveling to head office to use theirs is hit and miss as it's a considerable amount of fuel to get there and find someone else is already doing something that is in the way and given how many people are in and out it's almost impossible to plan for these things.

So I'm making 1. It will also vastly reduce the amount of grease needed as the spray pattern gives better coverage which means less trips to get grease.

All I need to know is how to effectively reduce the pressure in the spray head so the pressure in the cartridge tube is greater, to push the grease up while spraying.

The one in the main yard doesn't use any regulators and is fed direct from a 10 bar compressor, I have 9.6 bar available on the crane

 

[BrokenBiker]

Put a flow restrictor or pressure regulator on the feed to the canister then you can fine tune the setup. If you take the canister pressure as a bleed from the main air feed then the grease feed control would be automatic. Your problems would be over-feeding in summer and not feeding grease in winter.

The plan is to bleed pressure from the main line for the canister, but the way I see it in my head I need more pressure to canister than the actual spray head, other wise that would back feed into the cartridge housing, which is an issue I have with mk 1...

This is what I am loosely copying

 

[Pete.]

Presumably the canister has a dip tube?

Anyway, the one above 100% looks like a converted suction spray gun probably with modified drillings and metering needle. The paint sprayer doesn't need positive pressure in the pot it draws the paint up via venturi action so presumably the pressure feed is due to the much higher viscosity of the grease you're trying to draw up the tube.

If you're mk1 gun is pressurising the pot then I suspect that you need to increase flow through the spray nozzle and try to increase venturi action by bringing up the velocity of the air past the dip tube somehow, maybe by choking the flow across the tube (which is how a carburettor works). See if there is any way you can get hold of the one you're trying to copy for 20 minutes, have it apart and take some measurements.

 

[8ob]

Looking at what you are loosely copying I would say the aux pressure feed to the canister is acting down on a piston that literally stuffs the grease up the delivery tube. It must be along those lines to actually empty a cartridge, suction anyone will just leave a void in the gloop and it would stop working.

Bob

 

[Pete.]

Maybe a redneck version could use a BFO spring and have the trigger needle shut off the grease completely. No need for a dip tube then plus you could use ordinary cartridges.

OR

A piston-pump greaser like you see in the workshops with a really long hose and feed line from the gun to the pump. When you pull the trigger the piston pump activaes and forces grease into the sprayer.

 

[BrokenBiker]

Presumably the canister has a dip tube?

Anyway, the one above 100% looks like a converted suction spray gun probably with modified drillings and metering needle. The paint sprayer doesn't need positive pressure in the pot it draws the paint up via venturi action so presumably the pressure feed is due to the much higher viscosity of the grease you're trying to draw up the tube.

If you're mk1 gun is pressurising the pot then I suspect that you need to increase flow through the spray nozzle and try to increase venturi action by bringing up the velocity of the air past the dip tube somehow, maybe by choking the flow across the tube (which is how a carburettor works). See if there is any way you can get hold of the one you're trying to copy for 20 minutes, have it apart and take some measurements.

The one in the picture has no dip tube, it takes tubes of grease similar to a silicone tube, with a solid plunger at the bottom of the tube. The air feed presses up on this plunger creating the feed, grease ha snow here to go but into the head. The grease tubes on that model screw into the head then the cover fits over that and screws to the head separately. Air pressure is the only thing pushing the grease into the head.

This is what I am trying to replicate but I am making a stand alone tube with its own plunger to fill bulk grease into rather than using the available tubes as we aren't allowed to store those in satellite depots due to cost (apparently, we can have a 5 gallon tub if it though), but it will work effectively in the same way. My first version relied on a standard grease cartridge with a normal, sprung, grease tube and plunger, but the air pressure from the head was forcing the grease down, overpowering the spring and preventing it from feeding into the head.

Getting hold of it isn't really an option in the time frame I have as I'm flat out and won't be near the yard this side of Xmas unless something goes seriously wrong and ideally want this done in the next week or 2 as I've got jobs coming up that require a lot of Tele duties so more regular greasing required.

I have got a spray gun with a 2.0mm nozzle now and more adjustability than the previous attempt so will run a regulator between the bleed off for the cartridge and the gun itself so I can tweak the difference between the 2 and keep a slightly positive pressure to the grease cartridge

 

[Pigeon_Droppings2]

Could you maybe use a rubber bladder that inflated and pushes on a piston. Using a bladder means the seal of the piston doesn't need to be perfect.

 

[bricol]

I'm going to be the boring tw8t who points out under the Pressure System Regs, Pressure Equipment Regs, Health and Safety at Work Act etc, you are giving your employer a really good way to give you a hard time.

On your own personal crane in your own time you can do whatever you like if you are using it. As soon as you rock up and connect up to your work equipment to use it on your work equipment you are opening your employer, and you, to liabilities.

Anything using stored energy has a whole load of rules and regs.

I have to design systems, equipment used with those systems, as part of my job designing machinery (currently working on hydraulic powered stuff - had to point to point out to a colleage last week his chosen components had a safer working limit way under our proven loads) - it gets very complicated to comply with all rules and regs. Many arguments with older school engineers of the "it'll be-rite" thinking . . . these days, it's not.

 

[BrokenBiker]

Could you maybe use a rubber bladder that inflated and pushes on a piston. Using a bladder means the seal of

I'm going to be the boring tw8t who points out under the Pressure System Regs, Pressure Equipment Regs, Health and Safety at Work Act etc, you are giving your employer a really good way to give you a hard time.

On your own personal crane in your own time you can do whatever you like if you are using it. As soon as you rock up and connect up to your work equipment to use it on your work equipment you are opening your employer, and you, to liabilities.

Anything using stored energy has a whole load of rules and regs.

I have to design systems, equipment used with those systems, as part of my job designing machinery (currently working on hydraulic powered stuff - had to point to point out to a colleage last week his chosen components had a safer working limit way under our proven loads) - it gets very complicated to comply with all rules and regs. Many arguments with older school engineers of the "it'll be-rite" thinking . . . these days, it's not.

Fully understand all this...without sounding like an ignorant tw@...not bothered...my boss does little to help me in any instance, I have requested kit to make my job easier and less strenuous on my back given my recent hospital visit, got told there is a manual grease gun on the crane...explained to him that a manual grease gun is in no way suitable for greasing the jib, got told it hasn't been an issue til now so don't need any new kit for it...

Get bollocked for not maintaining the crane, get bollocked for using my own tools to do it, get bollocked if I ask for tools to do it properly...quieter life to just take care of it myself and not mention it... Testing will be done to ensure I'm confident it can handle the pressures involved and do the job properly with my own personal air supply before using it in anger.

The boss btw, is the same guy that was listed as the main reason 6 of us left kings...he then followed me and a mate to sparrows 2 months after we started...nothing has changed in his management style, and as much as it is starting to grate now, I still have a job to do and a back to preserve so at this point I'm fine with the consequences of using my own tools. My back is more important to me that someone having an issue with my tools.

 

[BrokenBiker]

Could you maybe use a rubber bladder that inflated and pushes on a piston. Using a bladder means the seal of the piston doesn't need to be perfect.

Probably not to be honest, a rubber bladder is beyond my abilities at the moment. Sealing the piston isn't going to be an issue, I have a 58mm bore tube I will be welding a cap onto, my hole to take the speed fitting, then will turn a puck with 2 o-ring grooves, thick enough it won't twist during use, hollow bottom to give as much surface area for the air to act on as possible. Basically replicating the piston in a silicon tube. I need a good turning project and an excuse to weld some aluminium. The top of the tube will be threaded 60x1.5, cap made to suit with an M12 thread to accept the link tube to the spray gun head.

 

[Turbo]

Why not use a standard pump action grease gun as a base for your sprayer.
They already have a big spring and plunger that force the grease quite rapidly out of a grease cartridge. Remove the pump gubbins to give the grease an unrestricted flow from the cartridge to the output hose.
Connect the hose to your spray gun and you should have a grease sprayer.
Most cartridge guns can be filled from a bulk grease bucket by sucking the grease into them.

 

[Munkul]

Shutz gun, manual grease gun cylinder, regulating valve, marry them all together?
Shutz type big, coarse venturi sounds like the right thing for this job.

 

[BrokenBiker]

Why not use a standard pump action grease gun as a base for your sprayer.
They already have a big spring and plunger that force the grease quite rapidly out of a grease cartridge. Remove the pump gubbins to give the grease an unrestricted flow from the cartridge to the output hose.
Connect the hose to your spray gun and you should have a grease sprayer.
Most cartridge guns can be filled from a bulk grease bucket by sucking the grease into them.

Tried it with an air powered grease gun I have, not nearly enough flow to get the spray

Shutz gun, manual grease gun cylinder, regulating valve, marry them all together?
Shutz type big, coarse venturi sounds like the right thing for this job.

Copying existing products that work as much as possible, only alterations in making are to allow me to use bulk grease rather than dedicated cartridge fitment.

First attempt used a normal grease gun cartridge and the spring wouldn't push grease into the spray head, and the air wouldn't pull it through so opted to go for a pre existing design that has been proven to work

 

[knighty]

Why not use a standard pump action grease gun as a base for your sprayer.
They already have a big spring and plunger

I was going to say this too but he beat me to it

If that wont give any flow into the spray head heat the grease up... even better if you heat the whole thing up.... dump it in a bucket of hot water for a while before use?

 

[knighty]

This video....

Its a cartridge inside a tube... pressurise the tube around the cartridge so the air acts on the piston bit on the bottom of the cartridge and push the grease out

Just a thought... is it 'normal' grease? Could well be some thinner stuff?

I think you'd be fine restricting flow woth a couple of needle valves.

Looks quite tricky to make.

I think I'd but a few cheap sprayers etc. to mix together... try to adapt a paint spraying gun to take a tube of grease, extend the paint pot so its long enough for the tube of grease to fit?


EDIT: of get a shultz type spray gun and an air grease gun... put a t piece in the tube of the shuktz gun and dump grease into there?