Co2 k3la k3ha question ...flow restriction @ regulator

Hi to everybody
Although I have been reading on this forum for almost a year…just yesturday I payed for a nathan k3ha set.
Since a good friend of mine gave me a 20lb tank with the regulator, I thought that was all I needed (besides the valve, hose, and fittings)

After reading a lot… I found that I will probably be having somewhere around 90 gallons of air @150 psi. (please do not discuss).
Also found out these horns need air flow and not just pressure.

I think, not sure the output regulator is 1/4 inch.
Only info I found was someone on this forum that said he had modyfied the output of the regulator into 1/2" output.
And I was thinking to just put a 1 gallon tank right after the regulator so I won’t get the air starvation at the horns.

There is a lot of people using compressed air, but none talk about the restriction air flow at rhe regulator.
I would like to get the most out of my k3s.
The will be mounted hidden in a 1955 vw bug!

Thanks for the inputs

I couldn’t help with the setup but that sounds like it will be a kick a$$ setup once completed on such a small car. Good luck to you!! I’d love to see some pictures once you get it installed.

It has been talked about a few times, but I don’t recall anyone reporting back how they did it - or if the regulator truly is a restriction. I wonder if you can just turn the pressure up at the “bottleneck” to get enough volume…

I do remember a thread where a guy talked about a small reservoir tank after the regulator (like you mentioned). What if the regulator leaked or went bad? Bye bye reservoir tank!

Well… There is a lot of pressure at the bottle neck valve wich is supposed to be open full.
Then there is a regulator valve with an output of 1/4", so there is 150 psi coming out a 1/4" hole.
The reservoir tank sounds to me as a solution, and as for the safety… A safety 200 psi blow off valve!
How big should I get the reservoir tank?
Remember it is a small car!
I was thinking something like 1gallon.
(will 1 gallon tanks have 1/2" output?)

Are they using this k3la at 1000psi

Its also on ebay!

Check this website - - They know a lot about Co2.

Gone through there… Besides expensive there is little information!
Thanks anyways

Maybe you could contact that Ebay seller. Try to either find out some info or even by the components from them. On their website they sell their 20lb bottle kit with K3 for 1200… and they sell a K3 for 900. So you might get a whole co2 setup for 300ish

What the?? No regulator?! These blokes can’t be serious. Surely they’re not blasting the K3 at anything close to a thousand PSI! No wonder there’s no video recording of that. My guess it’ll be a lot of hissing and squealing. The diaphragms (if they survive) won’t vibrate under that kind of pressure.

The 185db claim would be a load of bollocks anyway. There’s no air horn that loud and even if there were, it’d be unconscionable to sell or promote it.

Ok from another
“A regulator with a gauge is useless, because the pressure in a CO2 bottle will remain fairly constant until all of the liquid CO2 is gone. Then the pressure will drop rapidly as the last little bit of gas is used.”

And this is the hiflo regulator
Fast Flowing – non-freezing, high pressure 150PSI non-adjustable regulator. Nothing to adjust.

I’m not sure what that statement is meant to convey because it’s half right and half wrong. As long as there is gas in a liquid state within a pressure vessel, the force acting on the outlet will be the vapour pressure of the gas at the relevant temperature. In the case of CO2 at room temperature it’s between 800-900 psi. It won’t matter if you have 10cc or 1000cc of liquid gas in your tank, the pressure will be the same.

The regulator however isn’t useless, especially with high pressure gas, because it’s role isn’t to make pressure constant, but to bring output pressure into a regulated flow against the ambient (or outside) air pressure. Both of the regulators you posted (fixed without gauge, and variable with gauge) are a must if you want to run your air horn from CO2, Nitrox or anything like that.

The extra enquiries you’ll want to make is the maximum flow rate of the regulator with the manufacturer. The Airchimes are very thirsty on that side, but I don’t recall the exact figures.

Unregulated, the horns would undoubtedly be damaged, freeze up or at the very least wouldn’t sound right.

Completely right, there has to be a regulator to bring the pressure down to 150 psi or a little lower.
Yes what we need to know here is the cubc feet per minute that this regulator can output…
I couldn’t any info on this, but, That’s all there is!!!
This is the most unrestricted regulator!
This is the best option to go with Co2!
This is the biggest cfm 4x4 wheelrs use!

I just saw a chart that states for the nathan k3s
They are loudest when: 73 cfm @ 100 psi

If any body can find a side by side train horn test with compressor tank filled Vs Co2 bottle filled in a set of k3, it would be great!
(Am I asking for too much?)

Looks to be that the most cfm Co2 regulators these 4x4 wheelers use are just throwing 33 cfm… And thats half of what the k3s need…

Check the chart

I think I going to have to use a small reservoir tank…

Lawlz - I didn’t see the 185db.
There’s a reeeaaaal reputable company for ya!

Through my extensive search, I found you know about formulas, psi, cfm, and what not regarding train horns.

What do I need for getting:
73 cfm to the horns and @ what psi?
Since the co2 bottle is going to be my feeding machine with its normal regulator,
How big will the reservoir or feeding tank be?
Will it have to have a regulator to knock down probably some psi?

If you are looking at the chart wanting 70 cfm @ 90psi, just remember - that’s measured at the air inlet while the horn is blowing. That’s pretty hard for anyone around here to measure or test. Even, a “standard” installation of a K3 with 1/2" airline…do we really come close to the chart? IDK…? The experiences of a lot of people have helped us arrive at some accepted setups.

So I don’t know if formulas are going to get you there. Hopefully you can find somebody who has done it. They are around here, but sometimes getting details out of people is difficult. Anyway, one formula that would apply is Boyles law. P1V1=P2V2 So do those kits provide 33cfm @ 1000psi? That would equate to 220cfm @ 150psi. So I dunno.

The size of your reservoir tank depends on how fast it is being replenished and how long you want to honk. Safety valve or not, I personally would not put a tank between the co2 bottle and the valve. If you do, put a gauge on that thing. Maybe use another co2 bottle as the reservoir since it’s rated for it.

Yes there has to be some sort of regulator, especially if using a reservoir tank. The only way they’re getting away without a regualtor is if the tiny 1000psi solenoid valve is restricting the flow enough to not blow the diaphrams right out of the horns.

That’s about all the info I can think of - hope that helps.

Just re-read your OP and sorry… didn’t realise you already had the regulator. I was going to say that if you get the adjustable regulator, you can make up the required CFM’s (at the horn inlet) by just upping the pressure at the regulator. You’d need to get a flow & pressure gauge at the horn inlet to configure or dial in the system though. Too much mucking around I reckon.

The idea of the header tank isn’t a bad one in my opinion. Go via 1/2" from there to the solenoid and the horns. With a safety valve on the tank AND the regulator, you have a dual redundant safety system, so there shouldn’t be any concern about overpressure at the header. Keep in mind that even if both the regulator and safety valve somehow failed, there’s still the solenoid, which would blow open if faced with excessive pressure.

So basically you can rule out any safety concerns, but the problem I see in your case is space, right? If you’re mounting all this a VW, it’s going to get a bit tight I’d imagine. The CO2 in effect replaces the compressor and if you’re getting 33CFM @150psi out of that, that’s one heck of a fast compressor. Not even the bad boy XD4000 can get even close to those kinds of figures.

Normally a 5 gallon tank would be the minimum for running a K3, but given the ultra fast refill times you’ll get on the tank, you would get away with half that size for sure. Heck… even if you’re leaning on the horn button for an extended time and the header is depleted, you’ll still be honkin that Airchime at over a hundred decibels. As you can see from their performance charts, they have a really flat response curve and are stupidly loud at even low pressures.

Keep the design as simple as possible (i.e. minimum number of fittings) because leaks will be your biggest enemy working from a constrained air supply.

Wow… Thanks for the writing…
Well, this little project sounds good, for at least the two of us.
This fast feeding compressor has a better advantage, and is that “probably my pressure won’t be dropping, at least that much”
And if it does, it will recover really fast!

Thankyou again for the support, and now, I will stop reading about it and head for reading manifolds, independant brackets, fittings…

I can do most myself since I am handy

Just 1 more question…

I know I definetly have to buy a solenoid valve, 3/4 or 1/2?

Go 1/2". I honestly don’t believe there’s any benefit to running larger than that, simply because from what I’ve experienced with my system. I can open up on twin 1/2 lines to the horns. It makes no difference… as far as I can hear anyway. Maybe if you’re running a K5, other than that - no way.

Ok, but isnt there a restriction flow on these solenoids…
I mean, I should get
ID 1/2 hose And Any 1/2 solenoid?