Yes, compressors can blow up!

This came in to the ASK page on my compressed air information website recently.

“My xxxx air compressor blew up in the garage. Took out block wall & ceiling out above (12′). Why or how did this happen? 3hp 30gal.”
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Here is my response.
I can’t be sure since I’m not seeing the remains, nor did I see the compressor before the accident, but it sounds to me like your compressor pressure switch may have failed.

If the pressure switch doesn’t shut off the compressor at the high pressure set point, then the compressor will keep running and building pressure in the tank. If that happens your pressure relief valve is supposed to open to vent overpressure before exactly what you say happened, happens.

So, pressure switch failure, and then a PRV failure, or did you even have one installed?

Both failing at the same time is a very unlikely occurrence and I’m sure sorry that you were the subject of the unhappy results. Good luck with the next one.

And periodically carefully pull out on the ring of the PRV until air exhausts through it,  and then push the valve stem back into place until it seats to cut off the air flow. This  to make sure that it operates freely and can do so should an overpressure  occur.

Have you checked your PRV lately?

An explanation of a regulator manifold…

Hello Pablo, and thanks for sending in the photos. It makes understanding what you are questioning about on the website ASK page much easier to understand.

This is a custom compressed air regulator manifold, manufactured for or by your compressor manufacturer for their specific needs. There is nothing in this manifold that you cannot replace with standard, off the shelf components from a good hardware store that sells air compressors.

The item on the right of the photo is the PRV valve. Here’s more information on what they are and what they do.

Moving to the left, you have a standard, back mounted air gauge to show the pressure in the tank.

Under that appears to be a supply port that I believe  is for feeding the compressed air from the tank into the compressor regulator manifold.

Next, you have the regulator itself. Here’s more info on compressed air regulators.

The gauge for this regulator has been mounted to the left of the regulator on the manifold. This gauge is the one that tells you what the pressure setting of that regulator is and shows you the pressure that the air tools downstream from the regulator will see. The regulator gauge reading will normally be lower than the tank gauge on the right that shows you the tank pressure.

The gauge that’s on the left can could also be relocated to threaded into the air port shown at the top of the regulator should you wish. Putting the gauge there will not affect it’s operation. I am guessing that your compressor manufacturer put the gauge on the left to balance out the look of their regulator manifold.

Threaded into the manifold below the gauge on the left is the air line coupler. Follow this link to understand more about what these are and what they do.

You indicate that one of the items on your manifold have failed.

I believe it won’t be the PRV on the right, as they don’t normally fail except by opening at too low a pressure, and if that were happening, it would be evident by the air flowing out of the PRV.

Either of the two gauges shown can be replaced by a low cost, probably 1/8 NPT back mounted air gauges, with a pressure reading of 0-150 or 0-200 or so on the face. I don’t recommend you to buy gauges with pressure readings under 150, as many general purpose DIY compressors can supply more air pressure than that, and you want to see the actual tank pressure which will be shown on the right hand gauge when the regulator manifold is reattached to your air compressor.

If your problem is the regulator itself, then your compressor manufacturer has made it difficult to remedy that, from what I’m able to see. It looks like they many have welded the regulator into the manifold.

You may need to replace everything then, and if that’s the case, go to the hardware store with this complete unit in your hand, and tell the clerk that you want to build the same manifold using copper pipe and copper fittings. All of the parts you need will normally be off the shelf. You will need to be able to “sweat” copper to solder the fittings into the pipe manifold. If you have that skill, then rebuilding this manifold from scratch should be pretty easy.

The new regulator will have a threaded port on the right and left sides, and you’ll need to get that same size thread in copper to thread into the regulator.

The coupler will unscrew off the existing manifold, and make sure that the fitting you buy to replace the original is the same size as the one that’s there now.

When you reassemble, make sure that 1) you have the PRV installed 2) that you pull out and push back on the PRV ring to make sure the PRV moves freely so it can vent air should the system over pressurize.

Good luck.

Is a compressor for Christmas a good idea?

You see them advertised everywhere these days. A compressor, often with a fitting and hose kit, and even sometimes paired with an air tool or two… and all this for under $200.00. Are they any good?

Like many things, the answer is yes and no.

If the recipient is a DIY type with a workshop full of toys, and doesn’t have an air compressor presently, and their workshop is used for hobby work, then they are an ideal person for whom a low cost compressor would likely be a welcome gift.

On the other hand, if the person you are considering buying a compressor for has a workshop in which they do work to earn a living, then a low cost compressor and compressor kit is likely not for them, unless they want a small one to carry around for specific tasks.

You see, a compressor is simply a device that converts energy. A small compressor can convert electricity into stored energy in the form of compressed air, but not very much energy at a time.

Many air driven power tools use a lot of compressed air energy, and a small compressor cannot possibly convert enough electricity into compressed air to supply this type of tool.

The ideal tool for use with a small compressor is one that has a limit on the air use when the lever or trigger is pulled. A brad nailer, for example, will use only a small amount of compressed air energy when the nailer trigger is pulled. Therefore, a brad nailer, and some other types of nailers (I used a roof nailer for my garage with much success using a low cost air compressor) work just fine with a small, dare I say it, cheap compressor.

If the recipient or you want a small compressor to run a die grinder, a drill, or an impact wrench for examaple, then though the small compressor will run these tools, they convert electricity into compressed air so slowly, that  you are bound to become frustrated.

About-air-compressors.com is my compressed air website that offers tons of information about buying and using an air compressor. Oh, and if you are going to buy someone an air compressor that has never used one before, do them a favor and get them a copy of my eBook The Home Compressor.

One tank, two compressors?

1. Can I use one air reservoir for two compressor? Or if I have two compressors, I have to have 2 reservoirs also? Because we have 1 compressor, and we will add one more.

2. Should I add the air dryer to for the new compressor?

Thank you.

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Thanks for writing in.

Yes, you can use one air reservoir for two air compressors.

Since the two compressors will be generating air flow at different times and different pressures, it is necessary to put a check valve in each of the outflow lines to the reservoir, so that air cannot flow back down the line to the other compressor.

If you have an air dryer, I would install it downstream from the reservoir. Therefore, you would have two compressors both feeding air into the single reservoir, and the discharge line from the reservoir would then flow into the dryer, and from the dryer, to the plant.

There’s benefit in having the air flow into the reservoir before the dryer. It then has some time to cool naturally, to drop water out naturally, reducing the load on the dryer.

Make sure your reservoir has a auto-drain installed to rid the tank of water regularly.

Also, double check to ensure that the dryer will have the capacity needed to handle the outflow from two compressors.

 

Parts for an older air compressor.

I have an older compressor # 5F212.  I need air valves in the compressor head.  The parts people say this one is discontinued.  Can I get these valves from another compress’s part list or is there a sub??
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Good question.

There are so many manufacturers (or should I say suppliers ) of air compressors, finding parts for current, let alone older models, is always an issue.

You don’t indicate the manufacturer of your compressor, but it seems clear that you have contacted them, and they can’t help.

If you have torn down the compressor and have the parts, find a local compressor repair shop - here is a list - and take the broken part to them. They may be able to provide a like part, or advise a source.

If the compressor is valuable enough, a local machine shop can make the part for you. That will be expensive, but if the compressor is worth it, that may be the way to go. I don’t have a ready source for older compressor parts…sorry about that. If any visitor knows of a source for older compressor parts, please post it.

A compressor for Christmas?

Hard to believe that it’s mid-November, and we’re only 5 weeks or so from Christmas eve.

If you’re stumped in looking for a gift for Mr. or Mrs. Special, why not consider getting them a Home Compressor?

Not only are there some great deals on DIY (do it yourself) type compressors these days, many of them come bundled with an accessory kit and even some with a variety of air tools. For a couple of hundred bucks you can help propel someone from the hand tool, into the air driven tool world.

It is true that the low cost, fairly small, home compressors can’t run high demand air tools, air tools such as drills, ratchets, or impact wrenches very well, they can run them in small increments. Where the home compressor shines is in using one for brad nailing, blowing clean benches and tools, or even roofing nailing, for example.

If you opt for getting someone a home workshop compressor also steer them to www.about-air-compressors.com where they can access a website full of compressed air ‘how-to’s at no cost and post any questions they may have about using their new compressor.

And, if you do get a newbie a home compressor, then do them a really big favor and direct them to the Ebook sales site for The Home Compressor which will answer pretty much any questions they may have about how to operate and look after this most useful workshop accessory.

Compressed air for breathing?

One question or two from me, onboard here we do a lot of tank work cleaning painting etc, and we use our firefighting Breething Apparatus for the air supply. These BA are to big for our workers working in enclosed places, do you have a suggestion that we can place some airtanks outside the area were we need to work and have some connection between the air supply outside the tank and connected to a breething device to our workers. In this way our workers can walk more freely inside.
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Bill says….

Thanks for visiting about-air-compressors.com and for writing in.

I don’t doubt that you can get air tanks to feed a breathing mask for workers inside confined spaces. I do doubt that you would want to use a general purpose air compressor to fill those tanks.

If it were me, I’d be talking to the SCUBA people about high pressure air tanks for breathing. The compressors they use are able to pack an awful lot of air into a fairly small and portable single or double air tanks, can advise what type of air to use, and the regulators and masks you’ll need to use this air.

The air that’s compressed through the use of a general purpose air compressor will be full of moisture, perhaps compressor oil, and whatever particulates that the compressor intakes and sends along with the compressed air to the tank.

I understand the concern about the size of the BA you are using, but careful you don’t risk health for convenience.

Reducing the compressed air CFM

My compressor delivers about 90psi at 9 CFM.

I can set the gauge to 30psi, but how can I lower the 9cfm to 3cfm ?

Your answer is appreciated.

Wolf

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Hello Wolf:

That’s a tough one to answer simply, and often the solution is trial and error.

By setting your regulator to 30 PSI, you are reducing the flow through the regulator so that the downstream pressure never gets enough flow to allow that downstream line pressure to exceed that 30 PSI setting, give or take a few PSI depending on the quality of the regulator.

You are correct. That limits the flow somewhat, but really, the compressed air regulator is all about pressure, not flow.

In order to reduce the CFM to an acceptable level, you will need to restrict the air flow, and that’s commonly accomplished through the use of a needle valve. Not a flow control, but a Needle Valve. It can be a bit confusing, since a needle valve is a flow control device. If you follow the preceding link, you will get more information about these devices as they pertain to compressed air.

Inserting a needle valve into the air line to your application will both reduce the PSI temporarily until the line fills, and give you control over the ongoing  flow as your device draws air.

How will you know what the lower flow is? For that, you will need to install some sort of compressed air flow meter, unless there is something on your device that allows you to monitor the flow of air into it.

 

The compressor runs, but it won’t develop pressure.

Of late, many of the questions I’m getting about troubleshooting a compressor have to do with compressors that run, but generate very little pressure in the tank (far below the norm) and just keep on running.

I had some ideas about what was causing the problem, but also went and talked to a compressor repair depot, one that specializes in all kinds of compressors (even small ones) and got some more advice for you.

If you have a problem like this with your compressor, you probably want to read: Why won’t my ^%#$^$ compressor generate pressure?

“Watch when you are sizing your air cylinders…” says Norgren.

They write, “oversizing an actuator by one bore size can result in a 50% increase in the cost of compressed air required for the application. If care is taken in this initial step of the design process, every component upstream of the actuator will have a better chance of being correctly sized and applied”.

Sound advice, I’d say.

Here’s more information on air actuators.