3/8, 1/2 adaptors?? Help Please?

Automotive Onboard Air Systems
1

Ok so… I got some K3’s…

Couple of questions?

  1. wot size is the thread on the ports on the 8.5gallon tank?

  2. Wot size adaptors do I need for the compressors to go into the tank?

  3. I take it the pressure switch & 400psi sender unit is 3/8th??

The rest is easy peasy, just need to get a couple of things.

2

the grey box pressure switch is “1/8 NPT” the tank ports are “1/2 NPT” I belice the compressor is 3/8 if its smaller than the tank port its 3/8 npt

3

My dual Viair 400C units (and all other similar compressors I have seen) are 1/4" NPT. If you use the nylon tubing provided with the kit then there are probably some brass fittings to go from 1/2" NPT on the tank to 5/16" or 1/2" nylon tube for the horn solenoid.

The biggest problem I had with my custom setup was figuring out all the specific adapters which I needed. I must have made at least a dozen trips to the local hardware stores for adapters, manifolds, safety valves, gauges, fittings, etc. Finally I just purchased like 2 or 3 of every possible adapter, adding up to more than $100 all together, just to have it all on hand so I could finish my project without stopping for another store trip. Then I took back what I didn’t use for a refund and now I am all set.

Don’t forget to get some blue Loctite for sealing the threads. Well worth it to prevent leaks during install and it keeps things tight while you are on the road. Those K3s will shake things up a bit for sure!

4
  1. 1/2in NPT
  2. 1/2in NPT to 3/8in NPT Reducer Bushing
  3. They are 1/8in NPT

Please note that the width of the pipe is much larger than what its called.
http://www.plumbingsupply.com/pipethreadsizing.html
The nomenclature is based on the OD of the pipe the threading is designed to used with.

5

thats what i thought… =)

6

haha i did the same exact thing with the fittings…i just never returned the extra ones. and the purple loctite (545) works just as well.

7

Cheers guys… all temp linked up till the weekend when I start putting it all in properly!.. Gotta work on the two end fittings where the compressors go in… gonna try the locktight stuff. :smiley:

8

Loctite is critical to prevent leaks. I used teflon tape for my original setup and it was OK but it lost roughly 5-10 psi per day, sometimes more if there was a big temperature fluctuation from night to day.

When upgrading my system recently I used the medium strength (blue) Loctite and it was perfect. No leaks at all even when the tank sits unused for several days. And I have changed the system or replaced parts several times so I am glad that I didn’t use the higher strength formulas. That would just make it harder to change the setup and you have to clean the threads between changes so anything stronger than medium just creates more work.

Another valuable lesson learned: the automotive Type-T quick-disconnect fittings are superior to other types of fittings. They provide a much more secure connection with no leaks and they resist vehicle vibrations. You have to match the male and female fittings so they are all Type-T or you will have leaks.

9

All tanks are the same size?? wth are you talking about? if your talking about port sizes… this has already been answered by tiernan… and no they are not all the same size… they are 1/2 ports… there are no 3/4 ports oh his tank…
and hornblasters sels tanks with smaller ports… ( their chrome tank is all 3/8 ports) read a little bit before you go making random post that make no sense…

10

agreed with 7…

11

hahah ohhh man…

12

A few other notes I learned about fittings and air lines:

Most rubber air hose, pipes, and NPT fittings are sized based on inside diameter but tubing and tube fittings are sized based on outside diameter. So a 3/8" Goodyear rubber air hose has an inside diameter of 3/8" compared to a 3/8" nylon tube which has an inside diameter of only 1/4". Also, your airflow is only going to be as good as the smallest restriction along the path from the tank to the horns. If you have a 1/2" opening on the tank but you connect it with 3/8" hose and then use a 1/4" manifold and 1/8" adapters prior to the horns then the airflow rate will be constrained by the smallest 1/8" sections. So to get the best airflow you need to do the following:

  • use the largest inside diameter hose or tubing possible
  • use fittings and manifolds which match the inside diameter of the hose or tubing
  • keep the run from the tank to the horns as short as possible
  • install the solenoid as close to the horns as possible
  • keep the run from the solenoid to the horns as short as possible and equal lengths to each horn
  • use as few fittings and adapters as possible
  • minimize kinks or bends in the hose and tubing
  • mount pressure switches, compressors, drains, safety valves, etc. to ports or manifolds which are separate from the main air path to the horn

So in my installation I had planned to use 1/2" rubber air hose to match the large air tank opening but I found that most of the manifolds, adapters, and accessories required smaller openings so I ended up going with a 3/8" air hose and 1/4" NPT manifolds / fittings. So my total air path is 1/4" inside diameter which is equivalent to the 3/8" nylon tubing.

At least that is my current understanding. I am still learning but so far the Shockers sound awesome and have a quick response time on this setup and I have no leaks whatsoever. Hope to keep it that way and maybe even upgrade everything to 1/2" inside diameter at some point down the road. Any other pointers from the pros?