I previously asked about the [safety of connecting my 150 PSI air compressor to my auxiliary 120 PSI tank](https://engineering.stackexchange.com/questions/36833/is-it-safe-to-use-a-125psi-rated-auxiliary-air-tank-with-a-150psi-air-compressor). I was warned of possible compromise of the tank which can lead to injuries and even death. It was strongly recommended that I use a pressure regulator between the two tanks.

[![Porter Cable Pancake Compressor](https://i.stack.imgur.com/zyLhQm.jpg)](https://i.stack.imgur.com/zyLhQm.jpg)

* Maximum pressure (PSI) 150PSI
* Air Delivery 3.5 SCFM @ 40PSI
* Air Delivery 2.6 SCFM @ 90PSI
* Compressor Tank Capacity 6 Gallons
* Decibel Rating (Outdoor) 78dBA (one of the reasons for this setup)

[![Auxiliary Air Tank](https://i.stack.imgur.com/3rpVhm.jpg)](https://i.stack.imgur.com/3rpVhm.jpg)

* Maximum pressure (PSI) 125 PSI
* Tank Capacity 11 Gallons

My main problem with using an adjustable pressure regulator is that the user can inadvertently exceed 120 PSI using the knob. The innocent user shouldn't be pelted with shrapnel for going past 120PSI. Most regulators available well exceed this maximum.

I was unsuccessful in finding a fixed pressure regulator, at least not for a small air compressor. Perhaps it has a different name? Would a double stage regulator serve the same purpose?