Air Horn Compressor

I’m finishing our punch list before we start on the northern loop. I’m not sure how long the air horn compressor needs to run to fill the small tank on the flybridge. It seems to run nonstop and I’m wondering if there’s a safety release valve I’m not seeing?

Additionally, a ground wire gets noticeably warm while the compressor is endlessly running, so I won’t be using this until that gets sorted out.

In fact, I’m thinking of chucking the whole thing and going electric—but until I do, this will need to work. Does anyone have experience with electric horns that sound as deep and strong as an air horn?

I chucked my direct / electric in favor of compressor - tank. I could never get / find a direct compressor to deliver the air needed on demand, so I built my own. In your case, there needs to be a pressure switch on the tank, I suggest +/- : on @ 80 off @ 120 The other is a mechanical pressure relief safety valve in event that the electric press. switch is stuck ON ( closed ) I respectfully suggest that you drive the air compressor via a pilot relay because the contacts on the usual press. switches will not handle the motor current as the motor loads up .... my .02 CAD f

Sounds to me as though you have a leak!
Our very small compressor (12V) maintained a 1-gallon pressure vessel at 100psi with minor effort. The tank/compressor were in the lazarette feeding through a 35ft airline to the pilothouse twin air horns. Those Buells made an incredible noise (think, very large ship). Nothing electric can touch that sound.

I use a pancake 120Vac compressor in the engine room and air horn operates off a valve like a road tractor horn. In fact it is a road tractor horn ($30 off ebay!). I have the regulator set at 40psi and it is plenty loud.

Find out what setting the compressor pressure switch is set to. If set too high or if switch is stuck, comp will run continuous. You can get a well pressure switch from hardware store for cheap and it will work and be adjustable.

If you build a system from scratch, make sure you buy a pressure switch with the unloader valve. Also required is a check valve with an unloader port sized to fit the pressure vessel. The check valve goes between the pressure vessel and the pump. This allows the compressor pump to start with no load (no air pressure in the pump discharge hose).

I plumped mine to a very small (13 cuft.) scuba tank with an adjustable pressure 1st stage. Works great! Was worried about getting the tank refilled while on the Great loop. Haven't refilled it in 3 years despite using it a number of times.

Ted

kpoling said:

If you build a system from scratch, make sure you buy a pressure switch with the unloader valve. Also required is a check valve with an unloader port sized to fit the pressure vessel. The check valve goes between the pressure vessel and the pump. This allows the compressor pump to start with no load (no air pressure in the pump discharge hose).

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If he is running the DC compressor the p-switch with the unloader might not be needed. The dc motor usually has enough startup torque to start under a load. Key word here is "might".

Thanks all. There is definitely pressure in the tank. The horn sounds like it would bring down the walls of Jericho. I’ll keep looking for the manuals that are around here somewhere.

The compressor for my Kahlenberg air horn runs for 4-5 minutes to pressurize after not being used for months.

Kahlenberg horns are the gold standard.

hmason said:

The compressor for my Kahlenberg air horn runs for 4-5 minutes to pressurize after not being used for months.

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How big is your air tank? I may try again but I’m leery of that wire heating up.

While you’re at it add a quick connect fitting off a T. Get a Harbor Freight air hose and nozzle. Great for cleaning parts.

angus99 said:

Does anyone have experience with electric horns that sound as deep and strong as an air horn?

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I use a ship's air horn bought on ebay from a scrapper in India. Sounds like a ship. Nice in the fog. Boats stay away.
Air compressor systems have a switch to adjust start and stop pressure. Better systems have a bleed valve to relieve the pressure in the line between the compressor and tank. The tank has a check valve. That way the compressor starts without a pressure load and doesn't draw as many amps, saving the contacts and motor. The one shown is less than $20, inc. shipping, on ebay. I have one like it on a 5 hp.

hmason said:

The compressor for my Kahlenberg air horn runs for 4-5 minutes to pressurize after not being used for months.

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I will turn the compressor on tomorrow, hit the button and see if the horn sounds immediately. Seems like that would indicate the tank and hose between the compressor aren’t leaking if they’re still holding air from the last compression.

angus99 said:

...

In fact, I’m thinking of chucking the whole thing and going electric—but until I do, this will need to work. Does anyone have experience with electric horns that sound as deep and strong as an air horn?

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No way! Air horns have a much superior sound, particularly if one has more than one horn broadcasting more than one frequency. My Kahlenberg horns are backed up with an air cylinder about 10 inches in diameter and two feet in length, supplied by an air compressor.

I bought these at a salvage place after my old electric/air horns crapped out this week. Now I’ll have to figure out how to power them, assuming the diaphrams are still good. I like the way OCdiver has his set up.

Our boat came with triple Buells powered by a 20 pound CO2 cylinder. No compressor. Very, very loud. Loudest boat horn I have ever heard.

catalinajack said:

Our boat came with triple Buells powered by a 20 pound CO2 cylinder. No compressor. Very, very loud. Loudest boat horn I have ever heard.

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How many blasts/sounds the CO2 cylinders make at the rate of four seconds every 2 minutes?

Surely not everyone's cup of tea but....


For those of you that may want to avoid any electrical and pressure switches there is another way that I discovered when I got to know Libra's set up.


If there is an unused accessory drive with a cover over it on either your main engine or generator, you could install a mechanical air compressor there, add an unloading valve that is spec'ed at the pressure of your choice and run that air to a tank that will always stay pressured up as long as the engine in spinning.


Examples in pictures below:

First on the black (genny) engine you will see in the center of lower third of the picture a small compressor running on an accessory drive that grabs filtered air from the engine intake and puts out compressed air thru the unloading valve then up to the tank.

Second is a larger compressor on the main. It also grabs fresh air off the intake manifold, coolant from the water jacket, and runs air to the unloading valve and then to tank and coolant back to the water jacket.


Third picture is the unloading valve that serves both compressors and this one is a 7 BAR valve. After the tank there is an inline regulator that sends 5 BAR to the air horn.


This boat also has a larger 220V electric compressor but it is only used for working in the shop when the boat is not running.


Overkill I am sure, but also very simple in some respects. That is quintessential Libra. This boat used to have many air operated relays for start up and shutdowns demanded by the murphy switches. I have eliminated most of these relays in the interest of simplicity and gone to audio alarms.

catalinajack said:

Our boat came with triple Buells powered by a 20 pound CO2 cylinder. No compressor. Very, very loud. Loudest boat horn I have ever heard.

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Never heard of a separate co2 tank for horns. Dumb question and I realize it’s based on use but how often do you fill?

Easting said:

Never heard of a separate co2 tank for horns. Dumb question and I realize it’s based on use but how often do you fill?

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Before we left to do "the loop" in May, I exchanged the tank at an Airgas facility. The old tank still had gas in it. I bought the boat four years ago and had used the horn sparingly. I have no idea how many blasts one can expect from a full tank. I'm certain a reasonably accurate calculation could be done knowing the consumption of the horns, the expected volume of supply at regulated pressure, and an assumed length of blast. I'm happy with what I have cuz it is used so infrequently. Yes, some will say "what if" one gets caught in a fog bank. And I say what about those with air compressors that have high cycle times. No cycle times with the CO2 and very loud blasts. It's what came with boat and I choose to spend my boat dollars elsewhere.

Anyway, I am not saying it's the best solution. I only offer it as a different, but effective solution but one with unknown (to me) capacity.

"How many blasts/sounds the CO2 cylinders make at the rate of four seconds every 2 minutes?"

Buell triple air horns, according to Buell, consume 40 cubic feet per minute. A 20 pound CO2 bottle contains 175 cubic feet of gas.

Notes from a marine engineer friend.

I got this truck horn off of a wrecked Mack truck. The compressor is a small Senco used for finish nailers. It’s good for one good blow only then has to pump back up. I have plumbed up with quick disconnects at the compressor for other air needs.

I'd like a 'toot toot' horn for around the marina and then a very loud deep sounding horn to scare the Krap out of a boat coming at me or a captain with a bad attitude, trying to ignore my little bitty boat, or to use at the dark of night.
Alas, I have no space on the AT34.

Hi Angus, my suggestion is to remove one of the yellow wires (in your picture) that connects to the pressure switch. This should stop the compressor. Then wait 5 or so minutes and try the horn as I see it is operated by a seperate solenoid valve. If the horn sounds your tank is probably holding pressure and it is most likely the pressure switch at fault. If you stay with your compressor set up adding a small pressure gauge to the tank would be useful in tracking future faults and setting the pressure switch setting.

BeeJay said:

Hi Angus, my suggestion is to remove one of the yellow wires (in your picture) that connects to the pressure switch. This should stop the compressor. Then wait 5 or so minutes and try the horn as I see it is operated by a seperate solenoid valve. If the horn sounds your tank is probably holding pressure and it is most likely the pressure switch at fault. If you stay with your compressor set up adding a small pressure gauge to the tank would be useful in tracking future faults and setting the pressure switch setting.

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Thanks, BeeJay. Good ideas. I’ll let you know what I find.

psneeld said:

"How many blasts/sounds the CO2 cylinders make at the rate of four seconds every 2 minutes?"

Buell triple air horns, according to Buell, consume 40 cubic feet per minute. A 20 pound CO2 bottle contains 175 cubic feet of gas.

Notes from a marine engineer friend.

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While you can use a triple horn, a single horn with a 10 cfm consumption rate is more realistic. With a 20 pound CO2 tank at the above cycle rate, would last over 8 hours.

Worth noting: volume of gas consumed is not proportional to sound level. A pressure regulator allows you to adjust consumption and sound levels.

For my boat, the fog signal is done through the VHF sound and hailer option and an external speaker. Couldn't imagine timing and pushing the button every 2 minutes for hours while driving the boat. My horn is for getting peoples attention.

Ted

That "one long and continuous" blast has a way of reducing the number of blast.

psneeld said:

"How many blasts/sounds the CO2 cylinders make at the rate of four seconds every 2 minutes?"

Buell triple air horns, according to Buell, consume 40 cubic feet per minute. A 20 pound CO2 bottle contains 175 cubic feet of gas.

Notes from a marine engineer friend.

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psneeld, check with your engineering friend and ask him, will the CO2 freeze the horn valve faster than using compressed air.

OldDan1943 said:

psneeld, check with your engineering friend and ask him, will the CO2 freeze the horn valve faster than using compressed air.

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CO2 shouldn't contain any moisture (water vapor) as opposed to compressed air, so the valve freezing shouldn't be an issue.

Ted