Here's a video - is this regulator a mess or not?

Hey all - this is a head-scratcher for me. I’ve got a Viair 1.5-gallon compressor/tank with a THB R7000 regulator mounted to it, then about ten feet of 1/2" line to a solenoid valve which is mounted directly to an air horn - 1/2" line and fittings all the way. I’ve been having trouble getting the horn to sound correctly all the time - often there’s a weird, high-pitched squeal for the first second or so before the horn sounds correctly; I’ve discovered this tends to happen at higher pressures. So I’ve tried to regulate the pressure down to a level that it doesn’t happen.

But - I find that the pressure is in fact all over the place. Check out this brief video:

My understanding of a regulator is that it maintains constant outlet pressure as long as the inlet pressure is greater or even equal. The tank fills to 120psi and the compressor turns on when it falls to 90psi. I’m aiming for 65-75ish psi, but as you can see, when the horn is used, things get weird. So the inlet pressure is surely 90psi or higher until the compressor turns on again, but the pressure gauge is dropping to 40psi (?!?!) when the horn sounds, long before the compressor kicks on. I have checked to make sure the regulator is facing the right way.

This isn’t in the video, but previously I’ve noticed that when the compressor shuts off (presumably because the tank is at 120psi), the pressure will read 100psi or so, but as soon as the horn is blown even the shortest burst, it dropped back to 60psi, where I had set it at the time.

Is this a bad regulator or have I done something stupid wrong?

Also fun fact - there is a leak somewhere in the system - I have sprayed soapy water over everything three times over the last month, found two leaks, and fixed them, but now can’t find anything. Wondering if perhaps the solenoid itself is leaking very slowly? How the crap would I figure that out since the horn is plumbed directly to it? I tried spraying a piece of wood with soapy water and holding it over the horn bell but I couldn’t really tell anything…and I sure don’t want to burn the compressor up. Not sure how often it trips but it may be every two hours or so - really hate that but I’m stuck there too.

Many thanks, all!

Anybody? Really would love to know if this regulator is faulty or not.


Pull the regulator out with a simple bypass … it might be a bad regulator, or it might not allow the proper CFM for the horns to sound.


All regulators are not the same. In addition to pressure ratings there are scfm ratings to deal with. You have to match the horn scfm requirements with the regulator capacity.

scfm = standard cubic feet per minute. :D:D:D

OK, asked the guys at the place I bought the regulator to look into it - I’ll give them a call back tomorrow.

Wow, never realized regulators have a CFM capacity! Any guesses what a Grover 1510 might need? This regulator is pretty beefy - but may not be up to the task!!

Many thanks!

Replaced the Chinese regulator with an American one…and it just leaked air as soon as it reached the set pressure :confused: brought it back today after sitting at a railroad crossing for LITERALLY 45 minutes…it was the longest train I’ve ever seen…and then it STOPPED for 20 minutes. Finally got back to the place, swapped the regulator out, got it on tonight, and the horn is KILLIN. Pressure stays rock-solid and the horn has never sounded so good. I’ve only been trying to make this work for six months - pretty darn happy! Thanks for all the help, all!

You’re welcome :slight_smile: