Max. Pressure v. Working Pressure

yf23pav12

I use $70 compressor from  harbor freighter, the pressure drop from 40psi to 15psi when depressing AB tigger. I am ok with it. so your 7 psi is nothing.

 

Heh - you got what you paid for. Harbor Freight compressors are made in China and tend to be noisy.

I use $70 compressor from  harbor freighter, the pressure drop from 40psi to 15psi when depressing AB tigger. I am ok with it. so your 7 psi is nothing.

I'm not entirely certain what you mean by UK Imports, so I won't jump to conclusions.

With the exception of obviously different voltage requirements for different markets & some superficial cosmetic differences, the Sil-Air compressors mentioned are identical to Sil-Air & Sil-Air re-branded units supplied worldwide by Werther,  the same also applies to Sparmax & Sparmax re-branded units.

Milairjunkie

keilau:

But I am very diappointed at the deterioration of the quality at Sparmax and Silentaire.

There is no deterioration that I’m aware of.

keilau:

Even the cheap ones from China will not drop more than 2-3 psi in pressure reading when the airbrush trigger was pushed. I tried them with airbrushes from 0.2 mm nozzle to 0.74 mm.

That agrees with what I found for an 0.2mm nozzle with Sparmax, Sil-Air & "generic".

Yes, I take back the statement about "deterioration of the quality at Sparmax and Silentaire"." It did not happen to the models they sell in the US. Not knowing what the UK distributors do their import to UK. I should not have made that consclusion.

In the US, I usually expect less than 1 psi in pressure reading uncertainty from Silentaire, Iwata or Sparmax. With made-in-China airbrush compressors, up to 3 psi in pressure reading uncertainty is not unusual. All of Them can accommodate a wide range of airbrushes if you pick a reasonably powerful compressor. (This does not apply to UK imports.)

As a side note to the above, it should be noted that Sparmax makes the Iwata (Jet) compressors.  They are a solid compressor, just as I believe our units are as well.  (Personally, I think the Iwata units are a little pricey and am not sure why they are as expensive as they are). 

That being said, I have first hand knowledge of my company's product integrity, and I respect the integrity of Iwata-Medea regarding product quality and support, which to me should be given fair consideration when selecting a compressor (and/or airbrush for that matter).  I believe the selection of a product bareing the name of either company is a safe choice - first off because it is likely to be reliable properly performing product, and additionally because if a consumer has a product concern, companies such as ours, Badger/Thayer & Chandler, and Iwata-Medea will stand behind our products and do what we can to provide customer satisfaction.

There is no deterioration that I’m aware of.

That agrees with what I found for an 0.2mm nozzle with Sparmax, Sil-Air & “generic”.

As far as I’m aware, the Powerjet Pro uses the same motor / head combination as the Sparmax TC2000/AC500/TC620 compressors – which displayed similar drops to those quoted.

Do the length, bore & quality of the hose being used not have a direct impact on the indicated regulator pressure as soon as the trigger is pressed & a change from static to dynamic pressure reading occurs?  

Yes. I do. I wish I could.

kenbadger

Keilau,

With all due respect - relax, Badger stands behind anything it makes or distributes 100% +.

If anyone here doesn't know Badger cares more about quality and customer satisfaction than Badger - than they are not familiar with our company or our way of standing behind the products that bare our name.

I am glad that Michaels allowed the compressor exchange, if they had not and our further assistance was required in correcting the concern - I assure you we would have provided it.

Ken, It is reassuring to hear this directly from the boss. Thank you.

Milairjunkie

I've just checked a bunch of compressors from various manufacturers (Sparmax, Sil-Air & "generic") & found that they are generally loosing around about 7>8psi on the guage while triggering with an 0.4mm nozzle & about 2>3psi with an 0.2mm nozzle...................

Considering the compressor were of variant performance, format & design, the results were quite consistent, also keep in mind that both Sparmax & Sil-Air produce some of the finest airbrush specific compressors available. 

I have no reason to doubt your measurement. But I am very diappointed at the deterioration of the quality at Sparmax and Silentaire.

In the past 4 years, I have tried several airbrush compressors from various sources. Even the cheap ones from China will not drop more than 2-3 psi in pressure reading when the airbrush trigger was pushed. I tried them with airbrushes from 0.2 mm nozzle to 0.74 mm. The airbrush used did not seem to be a factor because the airflow from a single airbrush are all small compared to the airbrush compressor capacity.

For the Paasche DA400 and Sparmax TC-2000, it never drop more than 1 psi. MikeV had the same result with his old Badger MillionAir. I will be very interested in hearing from an Iwata Powerjet Pro user to see how his perform in this respect.

I purchased a pressure regulator from a airbrush seller on Ebay late last year. When I connect it to the same Paasche DA400 I have, the control setting was sensitive. And it dropped 3 psi in pressure reading when the airbrush trigger was pushed. I am convinced that it is not a true diaphram regulator.

Of course, I am not in the business of making or selling airbrush equipments. The tests I conducted were on very small number of samples and were not scientifically controlled.

Peace. Enjoy the compressor you have. Make more models.

I've been reading this thread with some interest & though better about getting involved, but......

Irregardless of the reasons for it happening & irregardless of weather it should happen, to experience an indicated regulator pressure drop from an airbrush compressor when triggering is perfectly normal & the airflow requirement of the airbrush/nozzle being used will have a dramatic impact on that drop.

I've just checked a bunch of compressors from various manufacturers (Sparmax, Sil-Air & "generic") & found that they are generally loosing around about 7>8psi on the guage while triggering with an 0.4mm nozzle & about 2>3psi with an 0.2mm nozzle...................

Considering the compressor were of variant performance, format & design, the results were quite consistent, also keep in mind that both Sparmax & Sil-Air produce some of the finest airbrush specific compressors available.

As has been said, weather the pressure is set with air flowing or not is irrelevant as long as the method is consistent, the pressure drop is also irrelevant as long as the user gets the airflow they require....

Keilau,

With all due respect - relax, Badger stands behind anything it makes or distributes 100% +.

Mr. Robisch is sending a general reply to the email we received, stating that a pressure fall off is normal (which it is), and is not identifying specific levels of acceptable drop in flow for a compressor/regulator.  I am confident if Herman more closely evaluated the situation he would agree something is amiss with such a notable pressure drop.  That being said,  I am not an engineer, but even I know that there is a variance in the levels of air pressure fall off dependent on the type of airbrush and the variance of nozzles in use on an airbrush at any given time.  The compressor I carry in my tool box and use during my IPMS, NMRA, and AMPS seminars drops anywhere from 2-12% depending on whihc airbrush I have connected to at anytime. Please don't make more of this than is there.  The more important part of Herman's reply was his advise on how to set the air regaulator with the airbrush trigger depressed.  If anyone here doesn't know Badger cares more about quality and customer satisfaction than Badger - than they are not familiar with our company or our way of standing behind the products that bare our name.

I am glad that Michaels allowed the compressor exchange, if they had not and our further assistance was required in correcting the concern - I assure you we would have provided it.

Bick

The second sentence in Mr. Robisch's reply is technically correct - for the compressor -  but doesn't address the regulator issue. Look at the  specs on any industrial compressor and you'll find something like '2.7 CFM at 40PSI and 1.8 CFM at 90PSI' [numbers for illustration only]. It's a shame he didn't address regulator pressure drop.

Bick, you may have misunderstood the specification of a tools compressor, or any compressor. The compressor motor provides a certain amount of power (rated in horsepower, but havs nothing to do with a horse ). The numbers you quoted is typical of a no name brand one-horsepower compressor. It can compress 1.8 cubic feet of air up to 90 psi per minute, but can compress more, 2.7 cubic feet, of air to only 40 psi per minute. It is a simple conservation of energy equation. It takes work to compress air. The compressed air has higher density at higher pressure. The amount of power you can get from the compressor to drive your air tool is more less constant. For example, if you need 5 CFM at 90 psi, you better get a name brand 2-HP compressor.

There 2 reasons that pressure from an airbrush compressor drops:

1. The user tries to draw more air from the compressor than it is designed for. Cheap airbrush compressor may be so underpowered that the pressure drops with very little airflow. In the airbrush compressor survey published in the August 2008 issue of FSM, better model can keep steady airflow up to 45 psi and other cannot keep up steady flow at 20 psi. Not all compressors are created equal. Quality costs money.
2. Cheap compressor uses a simple adjustable orifice to control the airflow. The pressure at the outlet side of the orifice changes when airflow changes. It is simply a cheap design issue. Better airbrush compressor has a single stage diaphram regulator where the outlet pressure stays steady when airflow changes. (High flow rate high pressure equipment uses 2-stage diaphram regulator as you see in a welding setup.)

You just cannot beat the law of physics and the law of economics. Quality does not come cheap. Fortunately for modelers, you can find high quality, name brand airbrush compressor for under US$200 today. Not bad compared to the price of model kits we paid for.

I was hoping that the Badger TC910 is one of them when I read your posts, but then my hope was dashed when I read Mr. Robisch's reply. You cannot expect Badger to back you up if the pressure drops 7 psi in a 20 psi setting because it is normal. 

The second sentence in Mr. Robisch's reply is technically correct - for the compressor -  but doesn't address the regulator issue. Look at the  specs on any industrial compressor and you'll find something like '2.7 CFM at 40PSI and 1.8 CFM at 90PSI' [numbers for illustration only]. It's a shame he didn't address regulator pressure drop.

Griffin

I sent the following email to Badger CS:

I was using my Aztek air-brush with a .4mm nozzle and had the pressure gauge/regulator set to 20 psi. When I depressed the trigger for air flow, the pressure on the gauge dropped to 13 psi. Is this normal or do I have a flawed regulator?

This is the reply I got:

This is very normal because you set this initially with no flow of air and when the airbrush is turned on you now have air flow. Compressor's air flow  is inversely proportional to pressure, in other words more air flow and lower the air pressure. It is better to set pressure  when the airbrush is on.

Herman Robisch 
V.P. Engineering
Badger Air-Brush Co.

To hear a VP of Engineering to say that it is normal for the pressure gauge reading to drop 7 psi at a 20 psi setting is upsetting. It gets worse when he said that the reading changed with airflow. He probably does not know what a diaphram regulator is supposed to work.

Drop 10% when pulling the trigger. Not so good a design. Drop 35% and considered normal? That is defective design or defective equipment.

Did Mr. Robisch understand how much damage he just did to the reputation of Badger?

I sent the following email to Badger CS:

I purchased a TC910 Compressor from Michaels on Saturday. While testing the compressor this morning I noticed a large pressure drop through the regulator when air was flowing through my air-brush.

 

I was using my Aztek air-brush with a .4mm nozzle and had the pressure gauge/regulator set to 20 psi. When I depressed the trigger for air flow, the pressure on the gauge dropped to 13 psi. Is this normal or do I have a flawed regulator?

This is the reply I got:

Griffin

Thanks for all the input. I figured the regulator couldn't be any worse on another compressor so I exchanged the one I bought with another TC910. When I tested this one, I got a 1-2 psi drop when I pressed the trigger. I figure that's not too bad. As it turns out, I'll adjust the pressure with air flowing anyway.

Interestingly, the lady at Michaels said that they get a lot of returns on their compressors.

It sounds like that the Chinese supplier of Badger may have a quality control problem. (Yes, I said it may. Not sure how accurate was the Michaels store clerk's statement about "a lot of" returns.) I sure hope that Badger has a monitoring system in place on their rate of return on these new Chinese compressors.

Some how, I will not be surprised if the Michaels store clerk's statement about "a lot of" returns turns out to be true. The making of a small oilless compressor requires precision machining and very tight quality control. These processes do not come cheap no matter how low the labor is. Some Chinese factory can do it, but just not cheaply. US retailer wants a cheap Chinese source for higher quality airbrush compressor may find out the hard way when return piles up.

Thanks for all the input. I figured the regulator couldn't be any worse on another compressor so I exchanged the one I bought with another TC910. When I tested this one, I got a 1-2 psi drop when I pressed the trigger. I figure that's not too bad. As it turns out, I'll adjust the pressure with air flowing anyway.

Interestingly, the lady at Michaels said that they get a lot of returns on their compressors.

GreenThumb

Even if they are losing 3-5 psi with a lower quality regulator I say so what?

It makes no difference in the spray pattern of the airbrush at all. If the air is not pulsating as it does with diaphragm compressors then the actual pressure loss when the trigger is depressed is inconsequential. 

Set it at 15-20 psi or wherever you prefer, spray some paint, and adjust the gauge to where it sprays the way you like it. Pressure drop doesn't affect the outcome. 

I know, I know! Someone even believe there is no difference between an Iwata and a made-in-China knock-off airbrush.

Quality is something you pay for.

If I get a $80 airbrush compressor at Harbor Freight with the regulator everything, no, I will not be upset if the pressure reading drops a few psi when airbrushing. I just live with it.

If I get the $50 Badger regulator or the $80 Iwata one and the pressure reading is not accurate, I will return the item and demand a refund. I will expect a very smooth and linear action of the adjustment knob too.

Since I paid $12 for my regulator at TCPGlobal and the adjustment is precise and reading stable, I am very happy. I don't know if TCPGlobal sells the same regulator today. I hope that they do.

Even if they are losing 3-5 psi with a lower quality regulator I say so what?

It makes no difference in the spray pattern of the airbrush at all. If the air is not pulsating as it does with diaphragm compressors then the actual pressure loss when the trigger is depressed is inconsequential. 

Set it at 15-20 psi or wherever you prefer, spray some paint, and adjust the gauge to where it sprays the way you like it. Pressure drop doesn't affect the outcome. 

While what the two Don (Wheeler and Stauffer) said is true that the absolute pressure value of an airbrush setting is not critically importnat, just a convenience, but it is not true that an accurate measurement in an airbrush system is difficult or expensive. In general, the max pressure and working pressure should be about the same.

We have known how to design good pressure and airflow control equipments for a long time (hundred of years) and we can do it inexpensively today. An airbrush system is a very low pressure and low airflow equipment, which makes the task relatively easy. I am an engineer, but I am not going to bore your with engineering jargons or equations. A good compressor for airbruahing need 3 elements:

1. You need a powerful enough motor that can generate enough airflow for the airbrush. You don't need a BIG motor. A 1/8-1/6 horsepower motor that provides 0.7 CFM at 40 psi is plenty for a single airbrush. But the compressor must be rated honestly. With an underpowered motor, the pressure drops off quickly when you start airbrushing. It not only happens with no-name cheap compressor, even the big name company makes underpowered compressor models at the low price end, but they are more honest about it.
2. The regulator shoudl be a true diaphram type with a small air port connecting the pressure gauge. Some cheap regulator is a simple orifice which provide very coarse control of pressure. Others may try to copy, but completely miss the design of a diaphram regulator. (If you are curious, you can google to find out what a true diaphram regulator is.) For airbrush, a cheap single stage diaphram regulator will be very sufficient and cheap to make. Of course, it needs to be designed correctly.
3. If the connection to the pressure gauge is a gapping hole, it affects the measurement accuracy. When you remove the gauge from the regulator, you should see a small hole of 3/16" or smaller. The manufacturer can easily cast this into the regulator body instead of leaving a big hole there.

MikeV (greenthumb) mentioned that his Badger MillionAir compressor will drop pressure by 0.5 psi when airbrushing. But you do not need this type of expensive, oil lubricated compressor to get that. I have only a Paasche DA400 compressor with a TCPGlobal true diaphram regulator. They costed me $120 (2008) and $12 (2005) respectively. The pressure never drop more than 0.5 psi with any airbrush I have. If Paasche and TCPGlobal make similar quality equipment today, they should perform the same. The Paasche DA400 or Sparmax TC2000 is typical of today's mid price range compressors. Not superquiet like the Badger MillionAir or the Silentaire range, but very quiet for indoor use. Best yet, they run cool. The cylinder head of a good oilless compressor should stay cool to the touch after long session of airbrushing. Heat is the worst enemy of these little oilless compressors. 

You don't need to live with a noisy tools compressor to get stable pressure either. Many establshed brand airbrush compressor will do quite well.

I would like people who gets 2-3 psi pressure drop pushing the airbrush trigger to post the brand and model of the compressor they have so that we can compare. The 3 psi or so pressure drop seems to be typical of the pressure regulator from Chinese sources today. There are higher priced airbrush pressure regulators. Will they work better?

Good luck and feel free to share your experience with the rest of us.

Griffin,

Lots of good comments here! Is 2-3 PSI significant? That asked, it's easy to obsess over what pressure drop can be expected and I guess the answer is "it depends"! Hook up a spray GUN and you'll see a real pressure drop. I think the regulators on your and my TC-910 are not the best (nor are those on most small AB compressors from any mfr.) but they work OK! Same for the pressure gauges - I doubt they're even Class C. My suggestion: Turn your TC-910 on and when it shuts off (tank full and pressurized), depress the trigger on your AB and, while depressing the trigger, turn the regulator knob to adjust the pressure up and down. If you can go from zero to 35-40 PSI, I'd call it done. Use and enjoy the compressor and get on with painting.

Again, the pressure drop is probably the regulator, not the tank or compressor.  You can have the biggest tank and compressor, and if the flow through the airbrush is near the maximum flow rate of the regulator you will experience a big drop.

An analogy is resistance and current flow. If you have a high resistance and flow a high current through it you will get a big voltage drop.  Pressure in a pneumatic or hydraulic system is equivalent to voltage drop in an electrical circuit.  High flow and high resistance create a big drop in potential.  Because airbrushes are low flow devices, the little regulators frequently used in airbrush setups tend to be high resistance devices.  You could try a different regulator if your regulator is externally accessible, but it is easier to adjust the thinning of the paint and your working distance and speed of movement of the airbrush than to tinker with different regulators.

If it can be made to work, don't worry about the pressure drop.  My current setup has a much greater drop than my old setup with general purpose compressor and regulator but I was able to adapt and it works fine.

I really doubt that Michael's, or any other store, would let you hook your ab up to a compressor and test it.  Good luck!

I emailed badger cs yesterday but haven't received a response yet.

I'll connect the AB and soap-test the connections to see how they fair.

I may be going to Michaels on Wednesday, I wonder if they'd let me hook up my AB to one of the other stock compressors to see if it does the same.

I always adjust the pressure with the airbrush at rest. It is only a reference point really so it's not that important which way you do it if you have a compressor with a tank. 

A 7 lb drop is not right on a compressor with a tank. My Badger Million Air only drops 1/2 lb. of pressure when the trigger is pressed on the airbrush. Are you sure all your connections are tight and not leaking anywhere? 

Spray the connections with a little soapy water and see if bubble appear. 

The amount of pressure drop with flow is an indication of the quality and capacity of the regulator.  Any regulator will show a drop from no flow to flow, but 7 psi is a big drop. This seems to indicate your airbrush uses enough air it is near the maximum that regulator can handle.

Still, that is not that big a problem.  13 psi is a tad low for me, but not much.  My latest setup runs 15 psi and I am getting a good job on both glosses and flats.  Ordinarily I like a bit more for flats, but it seems to work okay.

It is normal for the pressure to drop when the air is flowing from the airbrush.  Adjust the pressure regulator while you have the trigger open, before painting.

As an experiment, I hooked up my Paasche F single-action AB. (I have no idea what the specs. are for this brush or how to set anything up on it.)

When I used depressed the button, the pressure dropped 2-3 psi depending on the starting pressure. Less but still significant if I understand correctly.

For all I know, I'm doing something incorrectly.

You adjust the pressure while pushing down on the trigger. The pressure drop is due to the air flowing through the nozzle and depends upon the size of the tip. Don't think its a faulty regulator unless the pressure fluctuates while airbrushing.

Thanks for the responses.

keilau - I'll contact Badger later this week and see what they say. The one benefit this one has over my other compressor is this one is much quieter.

Don - thanks for the review. I'll check it out. [Edit - I read the review and had read it previously as linked in another thread on the forums.]

Bick - I have an Aztek airbrush and I was testing with the grey nozzle which is a .4mm nozzle.

Hi Griffin,

To answer your question, Yes, adjust the pressure while your spraying since that is the use condition. I also have the Badger TC910 compressor and I get a pressure drop of about 2 PSI when using my Evolution AB (0.2mm nozzle); what size nozzle are you using? That 0-100 PSI gauge is difficult to read accurately in the pressure ranges we use.