How a Regulator Works (detailed video)

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Ezana4CE

Ezana4CE

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Jan 15, 2021
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As one of the least mechanically inclined AGN members, I ask a lot of questions and sometimes need to read and re-read posts before realizing how lost I am. I am just beginning to get into minor repairs and more involved PCP maintenance. After replacing a regulator and attempting to rebuild an older regulator I realized that I did not totally understand how these devices function. So I began searching for static diagrams and cross sectional photos of regulator builds, but didn’t find much. I did find the above video and I think it explains the basics pretty well. Considering that I don’t know much about them, if you spot any errors in this presentation please point them out.



I’ve only seen this video posted in one other AGN thread regarding a regulator’s break-in period and I thought the video would be best suited in this forum so it can be easily referenced. If interested, here’s the original reg break-in thread started by @igolfat8 - https://www.airgunnation.com/topic/help-me-understand-regulator-break-in/

A couple of the respondents in the thread directly above have proven to be reliable members that have assisted me in gaining a better understanding on the topic.
 
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He did a very good job on that presentation. Clear, concise, and with good illustrations.

I did not spot any errors per se. If I could just add one thing...early in the video he pointed out the vent (breather hole) but did not make reference to it again when working through the operation of the regulator. The significance of the vent is that it provides the regulator a reference (atmospheric pressure) against which the output pressure operates, pushing the piston and compressing the spring. Potentially confusing matters is the illustration of the tube having no corresponding vent to the outside world. As shown, the small volume between the body O-rings will soon become pressurized by way of gas diffusion through the O-rings, and the regulator will cease to operate correctly.
 
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Greetings,

Spending quite a bit of time learning about PCP before I buy... in the springer world for quite a while.

Question: If the stem of the piston is hollow, why doesn't the air pressure in the regulator and reservoir stay the same? What air pushes the piston?
As a 30-year engineer I know there is a simple answer and I appreciate the input.

PSI.jpg
 
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At the opposite end--opposite the portion shown zoomed in--is a gold colored grub screw. As the output pressure climbs toward the setpoint, the piston moves to the right toward the grub screw. Eventually the piston meets the grub screw and seals off against it, preventing any further air from entering into the hollow piston.

BTW the end of the grub screw is typically fitted with a hard plastic seal so the piston can develop a gas-tight seal. This junction is the valve seat.
 
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Yes... and when I got into work this morning (I thought about it all through shower and drive in) I searched some sources. I believe it is Boyle's law.
The left side of the pic above is a smaller reservoir and as such will have higher pressure (closing the piston against the seal) than the larger right side reservoir.

Thank you for the reply.

boyles law.PNG

Question: Why would someone not want a regulated PCP?
 
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