Injector draws at first then falls off

[mrfixit]

On my ryko I've been fighting this issue lately. It's the Clear coat, dema injector - here no flow adjustment. Boost pump at ~ 200psi. There's no blockage into the chemical side. Or air leaks that I'm finding.

When the solenoid opens to run it, it will draw up to 12gph for a few seconds then it falls to about 1gpm. (typically I run it at 3.5gph, it's wide open to troubleshoot.)

My next step is remove the Injector from the plumbing.

I'll figure it out eventually but a search here didn't turn up any results and I'm sure someone has seen this before or will have the problem in the future.

Anyone able to help cut my troubleshooting time?

 

[mrfixit]

Update-
Took it off, don't see anything wrong, no obstructions and doesn't look eaten away. Also removed the foot valve no help. No tips on the injectior. Actually only drew up to 12 the first try, then subsequent tests it's stuck at 1.5 gph.. I see now it only draws the high rate with air in the line once fluid hits the injector it drops the flow rate. So I'm thinking there is something wrong with the injector that it can't draw the thicker clear coat anymore.

I know I had hooked another product up to this a few months this back, and presumably must have been thinner, the flow went to 11 with that and I had to back it way off.

While it did work before, I wonder if this is a problem of the injector design and I need a different one to draw thicker clear coat better. I have some spare. 083 injectors but don't think it will be enough flow for this, the dema has a pretty huge orfice comparatively. Probably why it doesn't want to draw thicker clear coat. Probably should replace with an adjustable flow injector, Type B to match to the pump. This injector says.. 1- 100gpm I have a 10gpm max pump probably not more than 8 running though this.

 

[mac]

Here's an educated guess. I've ran into the same thing before. In order for flow injectors to work properly there has to be sufficient flow through them. When your system turns on, the downstream line is empty, so flow is great, and it sucks product. Once the line fills, back pressure causes the flow to decrease, and less suction. You can test this by simply taking the line off of the machine and turning it on. You may need a bigger line also.

 

[mrfixit]

Thanks Mac, yeah that makes sense why it draws hard at first..

It's always worked in the past for the most part. Few things, I think this batch of ClearCoat is slightly thicker than before, or the boost pump may have lost like 20-30psi, or I do have a restriction somewhere I haven't found... Going to dig into it soon.

I didn't check the solenoid last night because it seemed to be flowing out the nozzles ok.... But maybe not.... I also think I found a check valve on the outlet side where it taps into the rinse line that I haven't taken apart yet
.

 

[rph9168]

Not sure where you are located but in colder climates most products tend to get thicker when exposed to colder temps. If your equipment room is properly heated and the containers are sitting off the cement on something like a pallet or stand it should be minimal but it still might thicken at least slightly. Even in a heated equipment room containers that sit directly on the floor will thicken if there is direct contact with the cold cement floor. Product already in the line would probably be warmer so it would draw normally but as you start drawing product from the container the viscosity might be thick enough to affect the draw.

 

[soapy]

On my ryko OHDs I use a .083 for presoak and .59 injectors for tri foam waxes and clear coats and rain X. I use the stainless steel injectors form Kleenrite rather than a Dema. The adjustable demas that come on the Rykos were too hard to keep consistent. The Dema you linked to is adjustable. To adjust it adjust the flow screw to where you want the slowly adjust the small screw on the side of the brown block until it starts to draw. It is a balancing act to get the flow and venturi balanced to where it will draw chemical.

 

[mrfixit]

Thanks Soapy... Well the one on it is like the pic, but not a type B. The rainshield has a stainless type B with adjustments.

So your able to run cc through the. 59 and get enough flow, I'll try it with the . 083 I have here and see. Thanks.

 

[DiamondWash]

Here is a pic from my wash it's the same setup Ryko OHD, I believe it's the check valve not fully opening creating back pressure causing your problem. Also the Clear-Coat line is the second from the top, I have my surface sealant line at the top.

 

[mrfixit]

Yeah mine is exactly the same except presoak air and water lines switched orientation, and I have blow down tapped in. Blow down is really nice. Yes there where the galvanized elbow taps to the brass hex check valve. Opening it now... I noticed last night it was screaming from that area.

OK the check valve off looks fine, it leaks a little but seems to open fine. I can blow through it too. It does make a vibration noise like a kazoo or something when you blow through it. Thought it was just cause I don't have much pressure. Maybe I'll have to disassemble it completely and see if there's something in there I can't see.

 

[gearhead]

Have you tried to run water thru it or maybe another chemical to see if it does the same thing? As rph9168 said you may have a thickening issue due to low temp or a bad batch of chemical.

 

[mrfixit]

It's thick but it should draw. It's no thicker than the rainshield shield and that draws with B type screwed down 3-4 turns..

 

[mrfixit]

Ok found the problem... Unfortunately the injector is bad!

After taking everything in question apart again, close inspection of the Injector with a flash light revealed a good sized hole worn through the inlet side of the venturi.

Unfortunately don't have a spare and will have to wait..