Air Pressure
- Thread starter Joe in NY
- Start date
I think they say adjust at the wall ie the regulator in the booth. Always have you pressure at the compressor wide open . A lot of different opinions on this .
Chris_Hamilton
Trying to be the best me, I can be
Jim and others will probably disagree but the way that I prefer and has given me excellent results is full pressure coming into the wall regulator at the booth. Quality diaphragm style regulator. I adjust it there and don't have a regulator on the gun. Hi flow couplings on my hose and gun. Started doing that when a Sata rep suggested it years ago. It has worked well for me. If you think about it though it is essentially the same thing as full pressure to the gun regulator then adjust at the regulator. This way I don't have a bulky regulator on the gun though.
Also keep in mind the relationship between volume(CFM) and pressure. More pressure does not equal more volume. It is the opposite. As pressure increases, volume decreases. As volume increases, pressure decreases. They are inverse of each other. Setting it at the wall does not rob you of any volume whatsoever.
Also keep in mind the relationship between volume(CFM) and pressure. More pressure does not equal more volume. It is the opposite. As pressure increases, volume decreases. As volume increases, pressure decreases. They are inverse of each other. Setting it at the wall does not rob you of any volume whatsoever.
dhutton01
Backyard Hack
I did a little navel gazing on this subject and concluded that if you are using a true regulator at the gun then set it max at the wall. If you are using a cheater valve at the gun then it is better to set the wall lower and just use the cheater valve for fine trimming.
My reasoning is that max pressure varies as the compressor cycles and therefore the cheater valve gun pressure will vary also. A true gun regulator will hold steady.
Not a pro by the way...
Don
My reasoning is that max pressure varies as the compressor cycles and therefore the cheater valve gun pressure will vary also. A true gun regulator will hold steady.
Not a pro by the way...
Don
You may not be a pro, but I know lots of pros (person that makes a living painting cars) that I wouldn't let paint my lawnmower. If you painted my lawnmower, I would be the talk of the neighborhood
I would think the small gun regulator would restrict airflow just as much or more than a big, quality wall regulator and 35-50 foot of air hose, but I may be wrong. Is there a way of measuring cfm at the gun, as in a gauge? I've always used a gun regulator, but can see how just having a fitting at the gun would be nice in most situations.
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anotheridiot
Member
I never heard this. Barry always says adjust the air pressure at the wall and let that make it to the gun, not full compressor.
Actually I was the one that started this about 25 years ago, set air at wall high as you can and adjust at gun from there.
At home never changed since I plumbed the garage 23 years ago 157 Lbs, one compressor system at work is 152 and the other 155.
'68 Coronet R/T
Oldtimer
For what it's worth, I am now doing things differently than when I started.
My compress is set at the full 175 psi capability. From there the air goes through about 30' of 3/4" copper tubing, through a particulate filter, into a refrigerated air drier, through another 15' of 3/4" copper into the booth. I have a regulator/water separator and another particulate filter on the wall which BEFORE I set at 120 psi and then control the psi at the gun.
NOW I put an air gauge on the gun set full open and with the trigger pulled on the spray gun set the PSI with the regulator on the wall. (starting to get these settings written down to eliminate the need for the gauge at the gun).
I like this method better mainly because it eliminates the air gauge at the gun which can restrict access to some areas when spaying.
As for whether the gun operates better I am not sure - most of my problems are from the guy handling the equipment!
My compress is set at the full 175 psi capability. From there the air goes through about 30' of 3/4" copper tubing, through a particulate filter, into a refrigerated air drier, through another 15' of 3/4" copper into the booth. I have a regulator/water separator and another particulate filter on the wall which BEFORE I set at 120 psi and then control the psi at the gun.
NOW I put an air gauge on the gun set full open and with the trigger pulled on the spray gun set the PSI with the regulator on the wall. (starting to get these settings written down to eliminate the need for the gauge at the gun).
I like this method better mainly because it eliminates the air gauge at the gun which can restrict access to some areas when spaying.
As for whether the gun operates better I am not sure - most of my problems are from the guy handling the equipment!
crashtech
Combo Man & Mod
@Barry and @shine disagree on this. I do both, so maybe my way is double bad. I keep the booth air pressure at about 60 psi with a big regulator and adjust it the rest of the way down at the gun with a digital gauge/valve. Pressure seems very consistent this way and I'm happy with it. Since the "cheater valve" is downstream from a regulator, the air pressure in the line in between the regulator and the cheater valve can be maintained at a constant level by the cheater, which is in essence a simple orifice that can be varied in size. Cheater valves that are connected directly to a hose coming off the air compressor cannot maintain air pressure, because the pressure in the line behind them is rising and falling as the compressor cycles.
anotheridiot
Member
Its just not safe to have full 175 psi making it to the gun. Dont care how clean your shop or booth is, one fitting pops or hose lets go and you have a mess on your hands, let alone the welt on your body from you trying to catch the snake.
'68 Coronet R/T
Oldtimer
If this is meant for me, you misread my post. I have a wall regulator in my booth that is adjusted down accordingly.
The rest of the system as been like that for nearly 10 years.
I guess I just don't understand the relationship between psi and cfm. I have a 10hp hydrovane with a 120 gallon tank that never goes above 110psi, but I could open 3 or 4 hoses with a fitting and it would stay there all day. It ran my old shop with an extra 120 gallon tank in the body area, running 5-6 people at a time, and I never remember running out of air. I don't understand the need for 150-175psi if you have enough cfm to maintain the pressure required to run the tool, but it may be over my head.
Chris_Hamilton
Trying to be the best me, I can be
I don't think there is a need. I think it comes from a lack of understanding of pressure and volume.
Think about it this way folks. Flow (CFM) increases as pressure (PSI) decreases and vice versa. Try inhaling through a straw for a while. You can do it but it is very hard to get enough air. The velocity of the air going into the straw is very high(PSI) but the flow is very little(CFM). Now switch your straw for a 1" diameter pipe. You are able to breathe much easier through the pipe with much less effort. The velocity of the air going in is much lower (PSI) but you are getting more volume (CFM) for your lungs.
Now how does cranking up the pressure give you better performance with something that needs volume? It doesn't. Pressure is there for the storage of air in the tank.
And explain please someone how adjusting the pressure at the wall with a regulator is any different than adjusting it at the gun with a regulator. It isn't.
EddieF
Top Banana
Only reason i can think of for running high psi is if plumbing lines are undersized & mile long in which case yes, it'll increase volume out the final destination. Say if 1/4" copper was used, you'd need a ton of psi to get volume whereas 3/4" pipe likely at 1/2 the psi puts out same or more volume.