I am wondering why all the different train horns don’t publish an airflow rate chart showing CFM starting at the minimum to the maximum pressure? Maybe even show it with different ID air supply lines too? If we knew the flow rate or consumption of the horns across our desired psi range (90-150 in my case) then we could calculate how long our tanks would maintain the desired sound. Without the CFM it is a guessing game.
I ask because I have a 100% true 1/2" ID air line to my Shocker XL and/or Omega AH-500 horns which I think should be supplying slightly more air than either horn can consume individually but it would be nice to confirm this. The trouble is that even with my 7-gallon tank I can only get about 5 full seconds of blast before I drop below the 90 psi range and then the horns start to sound lame. I was almost certain that the Shockers would consume a lot more air than the Omega AH-500, especially since the Omega manifold input is only 1/4" ID and the trumpets are much thinner, but both horns suck down the air at about the same rate with the Omegas lasting maybe just 1 second more before I drop below 90 psi. And when I blow the horns together my time is definitely cut in half, so I want to get a longer duration of maybe 10 seconds in the 90-150 range before my tank has to be recharged.
I am willing to upgrade my tank to a 10-gallon model but I think that is as far as I can go with my dual 400c units. They fill my 7-gallon tank in no time but I read that Viair only recommends 5 gallons for each unit so I guess there is a reason to limit them to 10 total. I don’t want to upgrade compressors right now, maybe never, so I am wondering how to calculate the increase in duration I will receive just by going up to a 10 gallon tank. If it is an additional 3 seconds or more then I would do it but anything less and it wouldn’t be worth the cost and hassle to change my install.
Also, if the main issue with compressor run time is heat buildup then why don’t these compressors have much larger heat sink fins? Seems like it should at least be an option to bolt larger heat sinks onto the heads. I have room to do so but would have to make my own heat sinks and I don’t want to invest the time since I am currently running below rated capacity anyway. But if I upgrade to a 10 gallon tank or more then heat may become more of an issue. I am wondering if I could just add a crude heat sink to each head that is made from some copper tubing, then add a simple 12-volt fan which is powered by a thermal relay when the heads reach a certan temperature.
My original setup was the Omega with a 1-gallon tank and 1/4" ID air line. It was fine for 2-3 short bursts in traffic, which is all I needed in most cases, but when trying to clear deer from the road about a mile away it just wouldn’t blast long enough. I never timed it with a clock but I would estimate it had maybe 2 full seconds of good sound then it started to trail off. 2 seconds doesn’t sound like much but when you count it out it is a reasonably long horn blast compared to the average vehicle horn use, which is probably no more than a quick 0.5 second tap. I just decided to upgrade because I wanted more like 5-10 seconds for those occasions when I need to warn from a far distance.
My current setup can easily go 5-10 seconds, maybe even a few seconds longer and still sound OK as far as the tone is concerned, but after about 5 seconds the volume drops noticeably which is a problem for the long distance scenario. What really convinced me that I need more air is when I parked beside train tracks and compared my horn with a real train running a K3. The traditional train blast for a crossing is 2 long, 1 short, and 1 long with the long blasts being about 3 full seconds each and the short being about 1 full second. This adds up to 10 full seconds and the real train horn still had the same volume and tone at the end. I tried to answer back with the same pattern from my truck and I could only get about 5 seconds into it before the volume started to trail off. The tone was still ok until around 8-10 seconds but it was much less loud with a soft muted tone at the end.
So the question I am trying to answer is: what is the maximum airflow or consumption rate of my horns from 90-150 psi? In my experience the tone and volume are acceptable in this range but anything less than 90 psi is either too low on the volume or the tone drops. So if I can find the maximum CFM for the Shocker across this range then it should be a matter of calculations to figure out the size of the tank needed to provide at least 10 full seconds in the 90-150 range. Based on my current setup it seems that I would need about double the tank capacity - 15 gallons or so - but anything above 10 gallons will require additional compressors which I want to avoid if possible. If I can get close enough with 10 gallons then I will upgrade to a larger tank, otherwise I will have to live with my current setup.
In your 20 gallon setup how many compressors are you running? Your signature only shows 2 units and I thought Viair only endorsed 5 gallons for each unit so it would seem that you are overloading the compressors even with the 480 duty cycle.
Hey Dan, why don’t you send me one of those XD3000’s for “load testing” on a super duty… I will provide you with feedback, and you let me keep it… sound like a plan?
What I have been wonder is how much louder is a horn at 150 PSI than 100. Maybe we am wasting air by not having a regulator in the line.
Has anyone done any testing on air pressure.
I know when I was testing my P3 with a 35 gallon home air compressor with the 3/8 inch regulator set at 90 PSI my horn made a tone of noise. Of course I was standing next to it.
