Just a brief update on my issue with the air pressure regulator. I never did manage to find fittings for it so I moved forward without it. Turns out, I don't really need an air pressure regulator with this compressor. The compressor is small and only puts out a maxium 56 psi. With the airbrush attached and loaded, the pressure drops to around 18 to 20 psi. This setup does a beautiful job, no paint blobs, no spitting, just a nice coat of paint.
Rich
Alton Junction
jjdamnit richhotrain By the way, the air pressure regulator has a 1/4"-18-NPT female input and output port, requiring 1/4"-18-NPT male fittings for starters. YES!!! So why have you been trying to make a "-27" (dash twenty-seven distinction) threaded fitting work with an "-18" (dash eighteen distinction) "standard" fitting- -whether 1/8 inch or 1/4 inch or NPT or NPS?
richhotrain By the way, the air pressure regulator has a 1/4"-18-NPT female input and output port, requiring 1/4"-18-NPT male fittings for starters.
YES!!!
So why have you been trying to make a "-27" (dash twenty-seven distinction) threaded fitting work with an "-18" (dash eighteen distinction) "standard" fitting- -whether 1/8 inch or 1/4 inch or NPT or NPS?
For the connection between the compressor and the regulator, I have a fitting that works. It is a 1/4"-18-NPT male x 1/8"-27-NPT female that fits from the input side of the regulator onto the air outlet of the compressor.
The problem is on the connection between the airbrush and the regulator. The air hose included with the compresssor has a 1/8" female fitting that connects to the airbrush, but I cannot find a way to connect the other end of the hose, a 1/8" female fitting to the output side of the regulator. I can find fittings where the 1/4"-NPT male fits into the regulator, but I cannot connect the other end of the fitting to the hose.
That's why I was so intrigued by your solution of moving that compressor fitting to the other side of the regulator. Unfortunately, my compressor fitting is different than yours and it won't work.
Hello All,
richhotrainBy the way, the air pressure regulator has a 1/4"-18-NPT female input and output port, requiring 1/4"-18-NPT male fittings for starters.
Hope this helps.
"Uhh...I didn’t know it was 'impossible' I just made it work...sorry"
gmpullman Several replies ago I had mentioned that many, but not all, airbrush compressors and accessories use both 1/4 and 1/8 British Standard Pipe Parallel (BSPP) fittings. These are straight thread and require an O ring to seal any pressure. Apparently my reply fell on deaf ears.
Several replies ago I had mentioned that many, but not all, airbrush compressors and accessories use both 1/4 and 1/8 British Standard Pipe Parallel (BSPP) fittings. These are straight thread and require an O ring to seal any pressure. Apparently my reply fell on deaf ears.
gmpullmanIf your regulator has 1/8 NPT and your moisture trap has BSPP you'll need an adapter like this. https://www.augustindustries.com/product/bspp-adaptor-r-1-8-to-npt-1-8/ If you want to go from 1/8 BSPP to 1/4 NPT look here: https://www.paascheairbrush.com/HF-116 BSPP is 28 threads per inch and 1/8 NPT is 27. No go. M5 x 0.5 BSPP is quite small as this is usually the thread on the airbrush itself. 1/4 BSPP is probably more common at the compressor. Good Luck, Ed
https://www.augustindustries.com/product/bspp-adaptor-r-1-8-to-npt-1-8/
If you want to go from 1/8 BSPP to 1/4 NPT look here:
https://www.paascheairbrush.com/HF-116
BSPP is 28 threads per inch and 1/8 NPT is 27. No go.
M5 x 0.5 BSPP is quite small as this is usually the thread on the airbrush itself. 1/4 BSPP is probably more common at the compressor.
Good Luck, Ed
By the way, the air pressure regulator has a 1/4"-18-NPT female input and output port, requiring 1/4"-18-NPT male fittings for starters.
Let me begin this reply with a few somewhat relevant comments.
First, my apologies to Dunderhead, the OP, for hijacking his thread. When I first replied to this thread, I never expected the extensive exchange of posts trying to solve my problem. I am grateful to jjdamnit for all of his time and patience.
Second, I have used the W.W. Grainger local branch near my home to order and pick up various fittings in an attempt to find the correct parts to add an air pressure regulator to my airbrush/compressor kit. Grainger has an outstanding website that provides critical detail on the sizes and dimensions of fittings.
When I first tried to install the air pressure regulator, I realized that it required 1/4" fittings versus the airbrush and compressor with their 1/8" fittings. What I didn't realize was that various fittings differentiated between NPT (tapered threads) and NPS (straight threads). That took multiple trips back and forth to Grainger to obtain the correct fittings.
The Grainger website provides not only specific information on fitting types and sizes, but each fitting also provides a "dimensional drawing". From what I can determine, all 1/8"-NPT fittings and 1/8"-NPS fittings have 27 TPI (threads per inch). Supposedly, NPT and NPS fittings are not interchangeable. However, as I mentioned in an earlier post to this thread, I am able to connect 1/8"-NPT female fittings to the 1/8"-NPS male compressor fittting. That said, I am unable to connect a 1/8"-NPT male into the 1/8"-NPS opening on the compressor with its original fitting removed.
I mentioned in an earlier reply that there are inconsistencies among the Harbor Freight website, the Central Pneumatic owner's manual, and the packaging regarding the size of the fittings. I mention this again here because I am now considering the purchase of a Central Pneumatic air hose which may solve my problem since that air hose has a 1/4"-NPT female fitting on one end and a 1/8"-NPS female fitting on the other end. That said, however, the website indicates that the 1/8" fitting on the air hose is 1/8"-28-NPS. To my knowledge, there is no such thing as a 28 TPI NPS fitting. I believe that all 1/8"-NPS fittings are 27 TPI. Could Harbor Freight be wrong again in this instance?
One last thing. I removed that fitting once again from the air outlet side of the moisture trap that comes off of the compressor. Both sides of the fitting are 1/8", absolutely no doubt about it. Using an Optivisor, I can see that the threads are straight, not tapered, on both sides. NPS or otherwise, neither side is NPT.
I believe that Henry (Big Daddy) said it best.
BigDaddy As for hose to compressor fittings, it is a confusopoly like buying a new cell phone or life or health insurance. It is intentionally too complicated to understand.
As for hose to compressor fittings, it is a confusopoly like buying a new cell phone or life or health insurance. It is intentionally too complicated to understand.
Edit Note: I submitted this reply at nearly the same time as Ed's reply. Ed's reply does shed some light on the entire issue of NPS fittings and 27 TPI vs. 28 TPI.
Overmod⅛ in. 'standard' NPT is 27 tpi... by standard. (Think 'T' as 'taper' rather than straight.) He indicated that he recognized this before you found a need to post.
If your regulator has 1/8 NPT and your moisture trap has BSPP you'll need an adapter like this.
Perhaps explaining to him why a "dash-twenty-seven designation" means something other than nominal threads per inch might actually accomplish something meaningful from all that verbiage.
⅛ in. 'standard' NPT is 27 tpi... by standard. (Think 'T' as 'taper' rather than straight.) He indicated that he recognized this before you found a need to post.
You keep using the wrong fitting between the Female output of the moisture trap to the Female input of the pressure regulator you are trying to install.
richhotrainI removed the 1/8"-27-NPS x 1/8"-27-NPS MxM fitting from the air outlet on the compressor and tried to replace it with a 1/8"-27-NPT x 1/8"-27-NPT MxM fitting. No dice. That did not surprise me. Although both NPT and NPS have the same thread angle, shape, and pitch (threads per inch), NPT threads are tapered and NPS threads are straight (parallel).
The fitting you circled in your photo is not a 1/8"-27- x 1/8"-27 (dash twenty-seven designation)-NPS fitting as you keep erroneously presuming!
It is a 1/8 in-27 (dash twenty-seven designation) NPT on one end with either 1/8 in-NPT or 1/4 in- "standard" NPT on the other side, no "-27" (dash twenty-seven designation) on that end.
That's why it is an adapter from "-27" (dash twenty-seven designation) threads to "standard" NPT threads!
One side of the M/M fitting is 1/8-"27" (dash twenty-seven designation) NPT to fit the airbrush hose.
The other side of the same fitting is a "standard" 1/8 inch NPT! (Or "standard" 1/4 inch NPT as on my unit.)
Note there is no "-27" (dash twenty-seven) thread designation on the opposite end of the fitting.
Trying to use a M/M fitting with the "-27" (dash twenty-seven designation) on both ends won't fit the Female port on the moisture trap or the regulator whether it's an NPT or NPS.
You need a M/M fitting with the "standard" NPT designation on both ends. Not a "-27" (dash twenty-seven designation) on either end!
PLEASE READ THIS VERY CAREFULLY:
Any fitting you use with a "-27" (dash twenty-seven designation) WILL NEVER work between the output of the moisture trap and the regulator you are trying to install inline- -no matter the size; 1/8 inch or 1/4 inch, or pitch- -NPT (tapered) or NPS (straight).
The "-27" (dash twenty-seven designation) is for the airbrush hose fitting. That's why it's a 1/8 in-27 (dash twenty-seven designation) NPT M to a 1/4 in NPT M ADAPTER!
The fitting you need between the moisture trap and the regulator, whether 1/8-inch or 1/4-inch CANNOT have a "-27" (dash twenty-seven designation)- -whether an NPT or NPS fitting!
I tried my grand experiment this morning without success. I removed the 1/8"-27-NPS x 1/8"-27-NPS MxM fitting from the air outlet on the compressor and tried to replace it with a 1/8"-27-NPT x 1/8"-27-NPT MxM fitting. No dice. That did not surprise me. Although both NPT and NPS have the same thread angle, shape, and pitch (threads per inch), NPT threads are tapered and NPS threads are straight (parallel).
I think the fact that the Central Pneumatic compressor has three different SKUs on the Harbor Freight website indicates that the manufacturer has taken liberties with the compressor design, at least as it relates to the fittings.
If I am going to find a way to install an air pressure regulator on this compressor, I need a different solution.
Have faith!
jjdamnit From there, it's a matter of matching the output of the regulator to the fitting you first removed.
From there, it's a matter of matching the output of the regulator to the fitting you first removed.
Yes!
Remove that fitting you have circled.
That's the adapter fitting you will need later, on the output side of the newly installed regulator to the airbrush hose.
The M/M fitting threads into where that fitting you circled was removed from on the moisture trap.
As I posted earlier, using an "O" ring between the moisture trap and the new regulator was needed to completely seal my system.
richhotrain The owner's manual states that the air outlet on the compressor is 1/8"-27-NPT Male. It further states that the air inlet on the airbrush is 1/8"-27-NPS Male. That said, when I just went back to look at the compressor box, it states that the air outlet on the compressor is 1/8"-27-NPS Male. So, there is an inconsistency between the owner's manual and the label on the compressor box that I just noticed for the first time. My best guess is that the label on the box is correct. This would make sense since the air hose connects perfectly from the airbrush to the compressor. Therefore, the air hose fittings must both be 1/8"-27-NPS Female. Interestingly, I do have NPT fittings where the 1/8"-27 female end connects to the 1/8"-27-NPS males. However, I have tried without success to connect a 1/8"-27-NPT male to a 1/8"-27-NPS female. Rich
The owner's manual states that the air outlet on the compressor is 1/8"-27-NPT Male. It further states that the air inlet on the airbrush is 1/8"-27-NPS Male. That said, when I just went back to look at the compressor box, it states that the air outlet on the compressor is 1/8"-27-NPS Male. So, there is an inconsistency between the owner's manual and the label on the compressor box that I just noticed for the first time.
My best guess is that the label on the box is correct. This would make sense since the air hose connects perfectly from the airbrush to the compressor. Therefore, the air hose fittings must both be 1/8"-27-NPS Female.
Interestingly, I do have NPT fittings where the 1/8"-27 female end connects to the 1/8"-27-NPS males. However, I have tried without success to connect a 1/8"-27-NPT male to a 1/8"-27-NPS female.
jjdamnit Is that the 1/8 inch NPT/NPS to 1/8 inch-27 NPT M/M fitting? As I keep saying, remove the fitting on the output side of the moisture trap.
Is that the 1/8 inch NPT/NPS to 1/8 inch-27 NPT M/M fitting?
As I keep saying, remove the fitting on the output side of the moisture trap.
It is a 1/8"-NPS Male x 1/8"-NPS Male fitting. The included air hose fits on this fitting. The included air hose will not fit on a 1/8"-NPT Male fitting.
richhotrainI removed the air outlet fitting on my compressor. It is 1/8"x1/8" M/M.
OK, Great!
That is the 1/8 inch NPT/NPS to 1/8 inch-27 NPT M/M adapter fitting that allows the airbrush hose to attach to the output of the moisture trap.
Put it aside because you will need it later.
No matter the size of the output of the moisture trap; 1/8 or 1/4 inch, the threads should be NPT.
That's why the NTP to 27 NTP adapter fitting is used.
If the new air regulator is F/F 1/4 inch NPT on both the input and output sides, there is a reduction adapter that will go from 1/8 inch M NPT to 1/4 inch M NPT.
On the output side of the new regulator; 1/4 inch NPT, you will need a 1/4 inch M to 1/8 inch F NPT.
Then you can use the 1/8 inch NPT to 1/8 inch-27 NPT- -that you saved- -on the output of the newly installed regulator with the step-down 1/4 inch to 1/8 inch NPT adapter.
Your best option is to remove the current output fitting from the moisture trap, take the compressor and the new regulator to your local hardware/big box store, and "trial and error" the fittings you need.
In my experience with Ace Hardware stores, there is a section in the tool aisle that has air compressor-specific fittings.
The plumbing aisle has a more generic selection of fittings that offer a bigger selection, including step-up and step-down adapters.
You just need to find the correct fittings and adapters for your needs.
Yes, I see that reference in the Specs. There is a similar reference in the Overview as well as on the compressor box which reads,
But, I honestly don't know what that means. With the included hose, you can directly attach the airbrush to the compressor. No 1/4" adapter is needed.
When I first read how you replaced the air outlet fitting on the compressor, I removed the air outlet fitting on my compressor. It is 1/8"x1/8" M/M.
Hello Rich,
The SKU on my unit is indeed 95630.
However, if you look under the specifications for all three SKUs it lists, "Thread Size- -1/8 in-27 NPT with 1/4 in-NPT adapter."
I may have an explanation for why the M/M fittings are different on my and your compressor.
My compressor has an SKU 60328. However, the website shows three variations: 95630, 69434, and 60328. The link that you provided in an earlier reply shows SKU 95630. Check the actual number on your compressor if you get a chance.
JJ, therein lies the problem. Your compressor air outlet port holds a 1/4 x 1/8 M/M fitting. My compressor air outlet port holds a 1/8 x 1/8 M/M fitting. So, I cannot do what you did. Interestingly, your fitting is brass. Mine is nickel plated brass for whatever that is worth.
Remove that fitting on the output side of the moisture trap!
On mine, it's brass- -but no matter.
That's where the M/M 1/4 inch fitting will go on the output of the moisture trap to the new pressure regulator.
Don't forget the "O" ring to prevent leaking on the "upstream" (input) side of the pressure regulator.
Then attach the pressure regulator "inline" (output) from where you removed that fitting.
That same fitting will be the "output" of the pressure regulator so the airbrush hose will attach to that.
Leave the moisture trap and the regulator in place.
That should give you what you are seeking.
Post Script: Thank you for reaching out and never giving up on the solution you seek. HTH- -JJDI.
I took two photos of the compressor.
In this first photo, the M/M fitting is the silver colored one coming out of the upper portion of the moisture trap. It is 1/8" x 1/8". Is this the fitting that you are referring to?
In the second photo, this is a view from above.
jjdamnit Hello Rich, Thanks! OK, that's the exact same unit I have. As I advised, remove the M/M fitting on the moisture trap- -the glass unit. Don't worry about the other dial gauge on the moisture trap- -leave it in place- -more on that later. The 1/4 inch to 1/8 inch 27 NPS is what you will use to "adapt" from the newly installed regulator to the airbrush hose. That F fitting from the moisture trap is where you will use the 1/4 inch M/M fitting to attach the pressure regulator with the "O" ring to prevent leaking. The dial gauge on the moisture trap stays in place. In the end, you will have both the pressure gauge on the moisture trap AND the pressure regulator.
Thanks!
OK, that's the exact same unit I have.
As I advised, remove the M/M fitting on the moisture trap- -the glass unit.
Don't worry about the other dial gauge on the moisture trap- -leave it in place- -more on that later.
The 1/4 inch to 1/8 inch 27 NPS is what you will use to "adapt" from the newly installed regulator to the airbrush hose.
That F fitting from the moisture trap is where you will use the 1/4 inch M/M fitting to attach the pressure regulator with the "O" ring to prevent leaking.
The dial gauge on the moisture trap stays in place.
In the end, you will have both the pressure gauge on the moisture trap AND the pressure regulator.
I'm a "suspenders and belt" type of person so I also used Teflon tape on the threads of the fitting along with the "O" ring.
Apply Teflon tap to the other side of the M/M fitting.
Then thread on the pressure regulator.
On the output side of the pressure regulator apply Teflon tape to the M/M 1/4 inch NTP to 1/8 inch 27 fitting.
You have to remove the 1/4 inch NTP to 1/8 inch 27 NPS to plum between moisture trap to the pressure regulator.
In the end, you will have the dial gauge on the moisture trap along with the pressure regulator.
The pressure gauge on the moisture trap monitors the total output from the compressor.
By installing the pressure regulator you can control the pressure to the airbrush.
As you use the airbrush you will see a fluctuation in the pressure regulator gauge- -this is what you want.
Hi JJ,
The answers to your three questions are:
1) The compressor is from Harbor Freight, Central Pneumatic No. 60328. It is a 1/5 HP 58 PSI Oil-Free Airbrush Compressor.
2) The air outlet is 1/8" male. (More on this later)
3) The air pressure regulator is also from Harbor Freight, Central Pneumatic No. 68223. It is a 150 PSI Air Compressor Regulator. Both sides of the regulator are 1/4"-18-NPT Female. I can confirm that those fittings sizes are accurate - - 1/4"-18-NPT Female.
Hello Rich, Thank you for your kind words. Which specific compressor are you dealing with (make and model)? So if I'm understanding you correctly the output of your compressor body is 1/8 inch female?On the regulator you are installing what size is/are the females?
Welcome to the nomenclature/nightmare of plumbing!
NPT refers to "National Pipe Taper" or the pitch of the threads.
Although the fittings are 1/8 inch on the airbrush hose, that pesky number "27" refers to the TPI- -threads per inch- -even though it is still an NPT fitting.
A "regular" 1/8 inch won't mate with the 1/8 inch 27, NPT, as you have discovered.
"NPS"- -National Pipe Straight- -will mate with an NPT with the same TPI. In this case, they are both "27."
There are a multitude of adapters that you can use to plumb the regulator inline eventually ending with a M 1/8 inch 27, NPT.
If you can answer the three questions I posed this will help us solve your plumbing dilemma.
JJ, thank you so much for getting back to me and for the detailed reply.
I never gave a thought to moving the compressor output fitting to the other side of the regulator. That was pure genius on your part. That's the good news.
The bad news is that the fitting on my compressor is a 1/8" x1/8" fitting, not a 1/4" x 1/8" fitting. I do have a 1/8" x 1/8" fitting on hand, but I cannot thread it on the opening created on the compressor. So, I am right back where I started. Ugh.
The problem seems to come down to the threading. What is so baffling is that the air hose will connect the airbrush to the compressor, but the Central Pneumatic fittings seem incompatible with standard fittings.
The thing that is so weird about all of this is that the air hose supplied with the compressor fits both the airbrush input port (1/8"-27-NPS) and the compressor output port (1/8"-27-NPT). These are the stated fitting sizes in the owner's manual.
Rich, check your e-mail.
Sorry for the delay in responding.
Here's my reply:
Hello Rich, Sorry it's taken me so long to reply. Thank you for reaching out to me via e-mail. I just looked at the Harbor Freight website and it appears that the exact regulator I have is no longer in stock. This seems to be the one they now carry is: https://www.harborfreight.com/air-tools-compressors/air-compressor-accessories/filters-regulators/150-psi-air-compressor-regulator-kit-with-dial-gauge-68223.htmlIt has Female 1/4 inch NTP fittings on each side. What I did to plumb this was to remove the 1/4 inch NPT to 1/8 inch 27 NPT adapter (airbrush hose) on the stock moisture trap/pressure gauge. I then used a Male/Male 1/4 inch NPT fitting to connect the regulator to the moisture trap. I found this in-store at Harbor Freight, but they are available and hardware and big box stores. On the moisture trap side of the M/M fitting I added an "O" ring to prevent leaking. Then on the regulator side of the M/M fitting I used Teflon tape on the threads to seal that side. The stock 1/4 inch NPT to 1/8 inch 27 NPT fitting that I removed from the moisture trap threaded in to the other side of the regulator, again using Teflon tape to seal this side. Without the "O" ring I did experience a leak. Adding this stopped the leak. Let me know if you need more info. Hope this helps.
Well, those are certainly distressing comments from Henry and Ed. I guess that I have no choice but to use the airbrush and compressor without a pressure regulator since I cannot find fittings that will work. Either that or return the airbrush and compressor and buy a pair of items with better control.
BigDaddyAs for hose to compressor fittings, it is a confusopoly like buying a new cell phone or life or health insurance.
I recently treated myself to an Iwata airbrush and I bought a 'package' that included a ten foot hose. I have dozens upon dozens of various fittings around here being a former pipefitter, I thought certainly I had 'something' that would work.
Nope, I was wrong. The Iwata compressor end of the hose required a ¼" BSPP thread (British Standard Pipe Parallel). This fits the flat face of the male fitting to the O ring in the threaded nut of the hose. I believe the end that threads into the brush is 1/8 BSPP.
From what I gather the airbrush end is a 1/8 BSPP thread.
My other brushes are Paasche models and I have two 'throaway' double action ones I use for scenery and other 'non-critical' stuff.
This is the fitting I required to go from ¼ NPT to ¼ BSPP:
https://a.co/d/d9HXn5q
It is called ¼G here (originally for German Gas thread but the pitch is the same as the British Pipe) but it is the same pitch as the British thread and fit the nut perfectly.