On-board air project for my 4WD
Appreciate you expertise and the hard work you have done explaining all about the air on the web. It’s just amazing.
I would be grateful for your opinion about the following.
To benefit from instant compressed air I am about to use my portable compressor 150psi/1034 kPa, 12V, 45AMP max, 150 LPM, which is only used occasionally to top up tyre pressure from sometimes low 16psi to 44psi max. during our off road trips, to an air tank.
I’ve come across a 10.56 gallon (40liter) air tank rated to 150 psi, work pressure 8 bar, tested to 20 bar.
Do you think that the tank is too big for the compressor?
I also found the Pressure Switch with Built-in Relay bellow. Do you think this could be suitable for the task? I am a bit confused about the psi On and OFFs stated in the description.
Tolerance is 5± of specified pressures
For 12 Volt systems only, up to 40 amps
1/8" NPT Male port fitting
Moisture resistant and tested up to 10,000 cycles.
Leads are pre-fitted with insulated 1/4" male push-to-connect terminals that are clearly marked
Dimensions: 108mm L x 57mm W x 57mm H
Part Number Description
90110 85 psi ON, 105 psi OFF
90111 110 psi ON, 150 psi OFF
90113 90 psi ON, 125 psi OFF
90118 165 psi ON, 200 psi OFF
Also the power cable will eventually be longer than the current 2.4m one as it will need to be mounted at the back of the ute.
I know that the positive wire should be as short as possible to minimise the amp. draw. Also motor should run to maintain enough supply voltage.
Is that an issue for this application set up Bill?
Also considering using the following for the setup:
1/4" FILTER REGULATOR which has:
•Maximum working pressure 150 p.s.i.
•Automatic water drain
•Polycarbonate bowl with metal bowl guard
•Robust metal construction
POLYURETHANE RECOIL HOSE
•Self retracting hose fitted with Jamec Pem 1/4" BSP male swivel fittings
•Recommended maximum working length: 90% of total hose length
•Compact diameter of coil
•Intended for compressed air applications only
•Excellent coil "memory"
Hose Length Hose Size O.D. Hose Size I.D. Max Working Pressure Fitting Material
6 m 12 mm 8 mm 860 kPa (125 psi) Brass
DIGITAL PRO TYRE INFLATOR
Do you think that could work?
Using a 12 VDC air compressor that is designed for sporadic, short duration use (such a refilling a tyre) to provide air to a tank may exceed the duty cycle of that compressor.
You need to contact the compressor manufacturer to determine if it can handle the long run time necessary, or, simply flip it on for a 5 minute run, then off for 10-15 minutes, then back on for 5 minutes and so on until the tank is full.
My compressor, which sounds similar to yours, cost me nothing, as I got it as a promo for service work done on my vehicle at the dealership. Retail, they typically sell here for under $20 so, if you use one up in your application, and it takes a while to completely wear it out, does it really matter?
You don't indicate what the air tank will be supplying - at least I didn't see that - so I don't know the frequency of filling it. That might be an issue.
The specs for your system, in terms of pressure rating, seem OK.
It were me, I wouldn't have the compressor running with a pressure switch, but a manual ON/OFF switch so that I could control the run time.
air tank size
(China, MI, USA)
I am building a machine that will have 6 pneumatic Rock-drills requiring 80CFM each at 90psi.
I have a compressor that is rated At 375 CFM at 90 psi and they need to run for about 30-60 seconds at a time but, lets say 40 seconds to limit variables.
1. How big of an air tank would I need?
2. I have about 35' of 2" hose between the rig and compressor. the tank will be mounted in this air line about half way. Do I need a larger hose diameter?
Harold, this is more a question for an engineer than a compressed air circuit designer and tool user, but let's have a look at it. And, anyone else have any comments for Harold, please chime in.
To run your rock drills you will need 480 CFM of compressed air at 90 PSI. Your compressor will discharge 375 CFM at 90 PSI, a shortfall of 105 CF for every minute your drills run.
The page Gallons to Cubic Feet conversion, linked from the tank section on the site map, will give you info about how big a tank you might need.
Yet, what is the tank size on the compressor now? You may have enough, given that you want to run the drills for 40 seconds, meaning that your supply shortfall is really only 68 CFM.
By the way, in my opinion, the production figures for air compressors are akin to those mileage figures that car companies give us! Theoretical, unless you are in laboratory conditions. But, the numbers they give is a place to start.
As to the flow through a hose, also linked from the site map page, in section Plumbing Compressed Air, follow the link to the Pressure Drop pages for info.
Hope this helps. Any engineer with hard data is welcome to add to this post.