Adjustable Air Pressure Switch (1 Viewer)

[Lo2aY]

I'm considering adding an adjustable pressure switch to the onboard air compressor.

The goal is to have an adjustable air pressure switch so that I could change the cut-off pressure to suite the tires. Let's say it cuts the fronts at 35 and the rear at 40 or 45.

This means I can be free to do other things instead of being stuck next to the tire.

I know ARB has a system that works with their lynx system but for us DIY type, have you found a solution to this?

I'm considering mounting this switch in line with the compressor switch. So that it would trigger before the original switch triggers (150 to 170 PSI for ARB twin compressor).

This new adjustable switch would be near the compressor and could be easily adjusted to suit the targeted pressure you want to set it to. something that is mechanical would be my preference but being that it's a switch, it would require 12V to stop the compressor.

Maybe something like this?

Amazon product ASIN B08P28PTW4
Thoughts?

 

[Dharma Dude]

I bought a couple of these ($10 or less each)

25 - 50 PSI 1/4" MNPT Air Compressor Pressure Adjustable Relief Pop Off Valve

They're adjustable. The ones I have are from 25-50 psi.
I have two (set at different pressures) and I build a quick connect T that is in-line to the air hose to the tire.
Works great.

 

[ntsqd]

Consider instead putting a regulator on your inflator. On the fly adjustments are right there. I'll suggest one like this: McMaster-Carr - https://www.mcmaster.com/4964K23/ While we're there I was recently made aware of these inflators, so I ordered one to see what the hoopla was all about. FlowPro™ Tire Inflator with Pressure Gauge - 100 PSI - https://jacosuperiorproducts.com/collections/tire-pressure-gauges/products/flowpro-tire-inflator-gauge-100-psi They're definitely a step up from what I have been using.

FWIW I use these on my OBA systems: https://www.automationdirect.com/ad...sure_sensors/pressure_switches/mps25-1c-p200d which are adjustable, but I wouldn't want to be adjusting them as often as you plan on doing.

 

[Lo2aY]

I bought a couple of these ($10 or less each)
View attachment 3454273
25 - 50 PSI 1/4" MNPT Air Compressor Pressure Adjustable Relief Pop Off Valve

They're adjustable. The ones I have are from 25-50 psi.
I have two (set at different pressures) and I build a quick connect T that is in-line to the air hose to the tire.
Works great.

How accurate is it? and how long have you been using it? this is really interesting.

Consider instead putting a regulator on your inflator. On the fly adjustments are right there. I'll suggest one like this: McMaster-Carr - https://www.mcmaster.com/4964K23/ While we're there I was recently made aware of these inflators, so I ordered one to see what the hoopla was all about. FlowPro™ Tire Inflator with Pressure Gauge - 100 PSI - https://jacosuperiorproducts.com/collections/tire-pressure-gauges/products/flowpro-tire-inflator-gauge-100-psi They're definitely a step up from what I have been using.

FWIW I use these on my OBA systems: https://www.automationdirect.com/ad...sure_sensors/pressure_switches/mps25-1c-p200d which are adjustable, but I wouldn't want to be adjusting them as often as you plan on doing.

The regulator would limit the flow of air to the tire. And will not stop until you stop it.

Maybe a digital pressure switch would be good? Something like the ARB pressure switch?

 

[ntsqd]

Are you sure about that?

 

[gnob]

this thread wasted more time thinking about saving time when co2 is the answer to the time riddle.

 

[Lo2aY]

Are you sure about that?

Yes I tried it.

 

[ntsqd]

Then I question your regulator. It is true that they are a flow restriction, but if one with a high enough CV is chosen then it's not a concern because the restriction at these flow rates is low enough to not matter.

As to the 'doesn't stop until you do", that's true but its also misleading. The time to pressure curve for any such system is a decaying logarithmic curve. There needs to be some supply system pressure in excess of the tire's pressure in order to increase the tire pressure. The larger that difference, the faster the new pressure can be reached. However, even with only one psi difference it will eventually get there.

CO2, ugh. I know that many favor it. I am not one of those people. I see it being good for one thing. Re-seating beads, IF the rest of the system can flow enough gas to make that happen without freezing up its regulator.

 

[Lo2aY]

Then I question your regulator. It is true that they are a flow restriction, but if one with a high enough CV is chosen then it's not a concern because the restriction at these flow rates is low enough to not matter.

As to the 'doesn't stop until you do", that's true but its also misleading. The time to pressure curve for any such system is a decaying logarithmic curve. There needs to be some supply system pressure in excess of the tire's pressure in order to increase the tire pressure. The larger that difference, the faster the new pressure can be reached. However, even with only one psi difference it will eventually get there.

CO2, ugh. I know that many favor it. I am not one of those people. I see it being good for one thing. Re-seating beads, IF the rest of the system can flow enough gas to make that happen without freezing up its regulator.

CO2 is heavy and requires fill-ups. It's not suitable for where I use my truck. I do however use it on my rock crawlers. Its fast and with a monster valve, takes less than 10 seconds.

The regulator I tried was from Parker.

I tried this

Amazon product ASIN B007FXJH2W
and this

Amazon product ASIN B007FXJM2M
They both didn't stop at the targeted PSI (30). They kept going to 50 PSI and I had to stop the test.

The flow was limited when the regulator was used.

I learned that regulators can't be used to stop airflow. They just limit the amount of air going through the line.

But I do see your point, and that's the reason I ordered them, I had that logic as well. I assumed the the regulator will reach an equilibrium with tire pressure. But the test showed otherwise. The regulator was installed on the line going to the tire. Maybe the line going to the tire was holding more volume of air? Not really sure.

Even if the regulator works, it would be slower than an inflation system. I would assume an adjustable pressure switch would do the trick?

You would have max CFM from compressor and a pressure switch to switch the compressor off when reaching the desired pressure.


Another Idea I had, was to replace the pressure switch on the ARB twin compressor to 40PSI. This way, I can air-down the tire 5psi or up 5 psi more.

The pressure switch would not stop the compressor if you had the line open. So maybe this would be a good solution.

 

[ntsqd]

Either the wrong regulator or something wrong with it. They will over-shoot the set psi when dead-headed (e.g. the pressure down-stream is close to their set point and no significant airflow), but IME only by no more than 5 psi and usually less than 1/2 that. 70%+ of the production / R&D tools that I design and assemble are pneumatic. The regulator that I linked above is the regulator that we use on everything.

But, it really isn't that hard or time consuming to simple check the current air pressure by turning off the compressed air supply long enough for the gauge to stabilize. If you're re-inflating with a manifold I'd put one of these valves between the QD fitting on the manifold and the rest of it, including the gauge.

McMaster-Carr

McMaster-Carr is the complete source for your plant with over 595,000 products. 98% of products ordered ship from stock and deliver same or next day.

www.mcmaster.com

 

[Lo2aY]

Either the wrong regulator or something wrong with it. They will over-shoot the set psi when dead-headed (e.g. the pressure down-stream is close to their set point and no significant airflow), but IME only by no more than 5 psi and usually less than 1/2 that. 70%+ of the production / R&D tools that I design and assemble are pneumatic. The regulator that I linked above is the regulator that we use on everything.

If it should work, I might have been working with the wrong regulator for the application. This might be the case. But since you design and R&D in the pneumatic world, i'd love to see your setup for auto inflating. I know you've described it, but it would be nice to see pictures.

The way I understand regulators, is that they (regulate) the air passing through a line to a set pressure, usually lower than the what is coming in from the compressor.

From what you are saying, and correct me if I misunderstood, but the regulator will stop the air passing through if the end of the line (in this case a tire) is at or around the set pressure on the regulator. Is this true?

If that is indeed the case, you have a huge market ahead of you for an automatic inflation device with selectable pressures. That is quick release and adaptable to many types of gauges/air-systems.

But, it really isn't that hard or time consuming to simple check the current air pressure by turning off the compressed air supply long enough for the gauge to stabilize. If you're re-inflating with a manifold I'd put one of these valves between the QD fitting on the manifold and the rest of it, including the gauge.

McMaster-Carr

McMaster-Carr is the complete source for your plant with over 595,000 products. 98% of products ordered ship from stock and deliver same or next day.

www.mcmaster.com

I'm not sure I understood this part. The goal from the setup I'm trying to do is to not check the pressure while filling up. I could check once the compressor stops at the targeted pressure through a switch or the method of the regulator.



the device I want to add inline is a quick release (ideally) and can be mounted just before the tire using couplers and is easy to mechanically adjust for a set pressure.

The device needs to be accurate so that you don't need to verify air pressure after each fill-up.

I think a device with these specs would serve most of us and will free us to do other chores while getting ready to hit the road.

 

[ntsqd]

Some regulators vent externally, some vent internally. In this case I'd expect that an external venting regulator would be the better choice.

The problem with regulators is the decaying logarithmic curve of time vs. pressure. If you dead-head or have a low consumption rate compared to the supply rate the regulator will stop at the set pressure. Eventually. If time is not a concern then a regulator with the desired pressure setting will eventually inflate the tires to that pressure.

If time is a problem then you could set the regulator at some pressure slightly greater than the desired tire pressure, or even a lot greater but below the compressor's average output pressure, and set a timer relay to turn off the compressor at some specific time. You would need to experiment with both settings to find the consistently reliable pair of settings, but once you had that it would be set it and forget it. Might think that just the timer is all that is needed, and depending on the compressor that might be true. However their output can fluctuate depending on atmospheric conditions so a regulator with a setting below the lowest output will tend to stabilize that whole part of the system.

The point of the slide valve is that you can easily and quickly turn off the supply, read the manifold/tire pressure, and turn it back on. This is what I built, but the manifold only does one axle at a time because I did NOT want to be carrying around a huge coil of hoses and because of the OX locker and the Detroit (two different rigs) I only really care about the rear axle being exactly equal tire pressures. The Detroit is an absolute need IMO, the OX not as much.

I think we're now flogging the corpse of the dead horse.

 

[ducktapeguy]

I know ARB has a system that works with their lynx system but for us DIY type, have you found a solution to this?

Yes. Buy a cheap compressor off amazon that already has this feature built in and cannibalize the display/ control board. Cost less than buying that pressure sensor alone and you get a free (small) compressor with it as a backup. It's a fairly simple setup.

Maxi Trac OBA system - https://forum.ih8mud.com/threads/maxi-trac-oba-system.1305864/

The only minor issue is if you have a very high flow compressor and tap the pressure sensor too close, you need to compensate for the backpressure. In the setup linked above, I need to set the pressure about 5 psi higher than my desired pressure because when the compressor shuts off the pressure drops about 5 psi. I plan on moving the control board to the rear and tap the sensor off the bumper tank, which will eliminate that issue. But that only happens with the maxi trac, it puts out a lot of air. With a slower compressor it's not really a problem.

 

[alia176]

I didn't read the whole thread so that obviously makes me an expert to reply here .

I love complexity as much as the next guy, but man O man, fellas seriously? One of the reason why anyone, including the OP, doesn't want to kneel down next to his tire for those extra few minutes is because the OBA system is quite possibly underpowered, and/or under delivering the air given their expectations. I'm kneeling at MOST four min per tire or less, depending on how much I aired down to begin with. I can hear the air going into the valve stems on both SUVs.

The 80 has a York belt driven air comp, the 4runner uses Air Zenith elec air comp. The 80 uses both sliders plus a 1.5g air tank. The 4runner only uses both sliders for storage with the plans of installing two alum 1.5g air tanks that were salvaged from a Land Rover.

Might I suggest any or all of the following for increasing inflation performances?
- get a 100% duty cycle compressor with its own electric pancake cooling fan on top of the head(s)
-run large gauge wires directly from the battery to the air comp. Use quality crimps, not from Amazon! The alum crimps open up over time due to heating/cooling cycles.
-if a relay/solenoid is being used, use a 100amp relay that uses ring terminals (not spade) on the high voltage side.
-keep the air comp cool during inflation duties by popping the hood (if located inside the engine bay)
-install air tanks to help out the air compressor. I use sliders as air tanks on both of my SUVs. Some folks use 2gal air tanks under their vehicles as additional storage capacity.
-fyi both of my systems have 80/105 psi fixed pressure switches. This range is suited for operating ARB air lockers w/o the use of a second step down regulator. Been doing this for 20 years.
-i'm using 3/8" air brake DOT hoses to supply air from the air comp to all storage locations. a 1/4" hose is used for tire inflation duties.


Cheers and happy blowing.

 

[Lo2aY]

I didn't read the whole thread so that obviously makes me an expert to reply here .

I love complexity as much as the next guy, but man O man, fellas seriously? One of the reason why anyone, including the OP, doesn't want to kneel down next to his tire for those extra few minutes is because the OBA system is quite possibly underpowered, and/or under delivering the air given their expectations. I'm kneeling at MOST four min per tire or less, depending on how much I aired down to begin with. I can hear the air going into the valve stems on both SUVs.

The 80 has a York belt driven air comp, the 4runner uses Air Zenith elec air comp. The 80 uses both sliders plus a 1.5g air tank. The 4runner only uses both sliders for storage with the plans of installing two alum 1.5g air tanks that were salvaged from a Land Rover.

Might I suggest any or all of the following for increasing inflation performances?
- get a 100% duty cycle compressor with its own electric pancake cooling fan on top of the head(s)
-run large gauge wires directly from the battery to the air comp. Use quality crimps, not from Amazon! The alum crimps open up over time due to heating/cooling cycles.
-if a relay is being used, use a 100amp relay that uses ring terminals (not spade) on the high voltage side.
-keep the air comp cool during inflation duties by popping the hood (if located inside the engine bay)
-install air tanks to help out the air compressor. I use sliders as air tanks on both of my SUVs. Some folks use 2gal air tanks under their vehicles as additional storage capacity.
-fyi both of my systems have 80/105 psi fixed pressure switches. This range is suited for operating ARB air lockers w/o the use of a second step down regulator. Been doing this for 20 years.
-i'm using 3/8" air brake DOT hoses to supply air from the air comp to all storage locations. a 1/4" hose is used for tire inflation duties.


Cheers and happy blowing.

Hi Ali,

The application I intend to use this system for is probably not your average person's requirement. We have an annual trip where we are off-grid for 14 to 18 days and are airing up/down every day. Sometimes, 3 times a day for 6 tires (2 for trailer). It gets real old real fast. Like you, I love a simple way of doing things. So I have a velcro strap attached to the inflator and use a stop watch to stop each tire. This allows me to do a 360 on the car and trailer. Also allows me to get other things done while waiting for 6 tires to inflate. It really makes difference.

The issue is finding a solution that would be very simple and could be adapted to any system with couplers. I couldn't find anything that can be adapted for this application. Other members have suggested a few ways to tackle this. I will try it out when I have time.

Thank you for the suggestions Ali.


- Luai

 

[alia176]

Hi Ali,

The application I intend to use this system for is probably not your average person's requirement. We have an annual trip where we are off-grid for 14 to 18 days and are airing up/down every day. Sometimes, 3 times a day for 6 tires (2 for trailer). It gets real old real fast. Like you, I love a simple way of doing things. So I have a velcro strap attached to the inflator and use a stop watch to stop each tire. This allows me to do a 360 on the car and trailer. Also allows me to get other things done while waiting for 6 tires to inflate. It really makes difference.

The issue is finding a solution that would be very simple and could be adapted to any system with couplers. I couldn't find anything that can be adapted for this application. Other members have suggested a few ways to tackle this. I will try it out when I have time.

Thank you for the suggestions Ali.


- Luai

Hi Luai,

Thx for the background, and I agree, your inflations duties are extreme. To that end, has any of the items on my list been done do you know? If the foundation isn't solid, the performance of your OBA will be subpar at best.

 

[ntsqd]

For the high amp contactor I suggest one of these: L-Series - Blue Sea Systems - https://www.bluesea.com/products/category/20/77/Solenoids/L-Series as I happen to know quite a bit about how they are produced and tested. The flying leads are a little awkward, but the contactors are solid.

 

[Lo2aY]

Hi Luai,

Thx for the background, and I agree, your inflations duties are extreme. To that end, has any of the items on my list been done do you know? If the foundation isn't solid, the performance of your OBA will be subpar at best.

I'm running a York 210 I think on my FSJ Chief. It's amazing how fast it is when filling up the 41" tires. It's almost as fast as the power tank. I'm really amazed.

On most vehicles, I'm using the ARB twin compressor. I think today they are the standard when it comes to compressors. It is mounted near the battery to keep the cables short. And is well ventilated. Unfortunately, I don't have space for air tanks. But i'm really not trying to just solve my problem. I think most of us would appreciate a mechanical device that would be integrated into the air system, that you can use to set and forget. Bonus is to make it detachable and be able to use on any compressor.

ARB has this system in a form of electronic device that is used by their lynx system. It involves using a phone and software to make it work. Which I really don't want electronics in this application.

I think @ntsqd is on to a solution here. I just want to see how it works in a real world setting and hopefully we can all benefit from it. When I get around to buying and installing his suggested system, I will share my results here.

In a way, I'm surprised with how large the 4WD market is today, yet no one is tackling this. The market is offering all sorts of useful and non useful products. It's a matter of time where someone would offer an easy solution to regulate tire inflation.

 

[alia176]

Very cool and wow, 41s

 

[on the rocks]

I took a shot at this with an Accuair system and 3/8" feeds for quicker fills on the 80 thinking I could do 4 separate feeds to all 4 corners and set a pre determined PSI on each corner and let it do its thing both on air up and down. Turns out there is some sort of safety setting on the system to only allow a quick burst of air then the valve closes. I assume this is to avoid blowing out an airbag of the valve was to malfunction and stick on. It would have worked other than this feature.
If you could hack the brains of the ECU to get the valve to stay open until the desired PSI hits, I bet you could make it work. I can do several short bursts of air and have a readout of the PSI until I hit the desired target but unfortunately nothing more. Unfortunattly this takes forever since the volume of air in a tire is so much more on the tire vs. air bags.
I thought about doing a manual ARB switch and override the PSI triggers in the system but after talking to tech support I decided against it for now. They wont support replacement valves and if I was to fry one I would need to buy the entire tank and valves...
Anyway, I can tell you what won't work lol. If someone was ambitious they could use their system and tweak it to work for the tires as it would be the same concept. They now offer Jeep and Bronco air suspension systems and they would be able to pull this off but not too sure they are interested considering the cost to bring to market would be way more than anyone would be willing to pay.
As a thought you could look at a 12v Pneumatic normally closed solenoid valve with an adjustable pressure switch that should work. Good luck!!