nathan install question

Hi Im new to this site and have some questions, I purchased a set of nathan horns used, now they were told to me that it was an K3 horn but as I got it in the mail it appears to have an K5 manifold with 3 horns which I didnt mind, but now as Im trying to install on my ford f-350 Im running into some issues such as the inlet for the air line, dose it have to be at the bottom of the base because I see plugged holes from the sides but dont know if I could use those for air inlet for the horn and plugging the bottom due to room issues Im having because I want to keep my spare tire.

Ill post some pics of the set up I have so ant info will be greatly appreciated.

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Ok im new to all this size and fitting term so if im wrong please dont beat me up too bad, where the feed line would go in from the base of the manifold its 1/2 inch npt and the one I want to use from the front base of the manifold is 3/8 npt with push lock fitting, so my question is will the 3/8 port on the front of the manifold be good enough for the use of this horn?

Welcome to the forums. Yes it’s a K5 high mount manifold with block-off plates.

You can use the port on the front. It shouldn’t be a restriction. The inside diameter of a 3/8" npt fitting is larger than the I.D. of your 1/2" DOT tubing.

If you are concerned about flow, use straight fittings wherever possible.

Ok thanks for the info on I that im going to the plumbing supply house tomorroow

Also just incase the plumbing supply house wont have fittings for air where else could I try, also im located in new jersey if that helps

Lowe’s and Home Depot will have all the NPT fittings you could think of, as should Ace Hardware and Tru-Value (and similar hardware shops).

If you can’t find it at one of those places, they can special order for you or you can find them online as well.


I bought my fittings on Amazon, but a local supplier would save you shipping.

Thanks for the info im going to try today to find so ill keep you posted

You know the really cool thing about having a K5H manifold is you have the option to buy the extra bells you need, and that would sound awesome.


with the location to where I want to mount the horns I dont think I have enough room for five horns

I went to home depot and lowes and no luck, apparently no one knew anything of what an air fitting was and they said they only sell water fitting so I came home and ordered everything off line.

Yeah, they don’t know what you need.

You’re looking for brass NPT connectors. Let me check my extra parts box when I get home from night shift and I’ll get you the SKU numbers from Lowe’s/Home Depot so you can ask them for exactly what you need.


Ok I have my horns installed and it went good, ill post some pics tomorrow and they sound great, but I did have one question what is the psi supposed to cut off the compressors at my gauge we t up to 190psi before I cut off myself, I thought the pressure switch was supposed to cut off at 150psi but maybe someone would let me know what it should be.

What style of pressure switch do you have? It probably says the pressure range on it.

What model of Viair compressors are those? If they’re rated for 200psi, you could try going a little over 200.

If you’re sure it’s a 150psi PS, then tell us how it’s wired.

I have viair 444c compressors and the pressure switch is 200psi, I shut it down myself at 200 but I let it run yesterday and it did shut down at 201 but maybe my pressure gauge is off a little, but my question is it safe for that small tank to be at 200psi?

Your gauge is correct. It wouldn’t be off exactly 50psi.

So the 444’s are rated for 200, but I don’t know about the tank. Is it originally from Hornblasters? I think they recommend 200 max.

Couple things about trusting a used tank at 200… Do you know how old it is or how rusty the inside is? Also how is the bracketry for the compressors attached to the tank? Is it factory or did someone add it?

The tank id from horn blaster but dont know how old it is and as far as I know when I pulled the drain plug there was no water and I didnt see any rust, the bracket are the factory ones I just had them shorten to fit under my bed cover

I’m not aware of any tanks from HB that have brackets welded on.
Most of their tanks are rated at 150psi, but they say 200psi max.

Whether it’s from HB or not… Is it stamped with a rating?

Glad I’m not the only one with that horn setup!!

201psi isn’t anything to worry about on a 200psi switch. I bet if you look up specs they are allowed to be off +/- a few PSI’s. Also 99% of the tanks I’ve seen have a rating of 200psi, I think for Hydro-testing the need to be able to handle 2X the working pressure? Double check your tank though if your not sure.

man those horns on the top of your tool box must give the full affect, living here in jersey someone would just steal them from me if I had mines in the open