# Acetal disc o-ring upgrade

**URL:** https://forum.bulletcentral.com/t/acetal-disc-o-ring-upgrade/319
**Category:** Hyperbloc
**Created:** [July 8, 2026, 1:49pm UTC](https://forum.bulletcentral.com/t/acetal-disc-o-ring-upgrade/319 "2026-07-08T13:49:44Z")
**Posts on this page:** 1
**Page:** 1

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### Author: ![stuart.graham](https://forum.bulletcentral.com/user_avatar/forum.bulletcentral.com/stuart.graham/32/27_2.png) [@stuart.graham](https://forum.bulletcentral.com/u/stuart.graham)
#### Post date: [July 8, 2026, 1:49pm UTC](https://forum.bulletcentral.com/t/acetal-disc-o-ring-upgrade/319/1 "2026-07-08T13:49:45Z")

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We have made an improvement to the pressure cap seal which utilizes an acetal disc to keep the o-ring in place. We are providing this, free of charge, to all customers who have purchased a Hyperbloc100 from previous batches. All Hyperbloc100’s from batch #3 (batch numbers are now being laser engraved on the plenum body) already have one of these discs installed.

Note: If you are experiencing a leak from the pressure cap, you should also inspect the o-rings in the valve housing chamber (3). If air is getting past one of those, it can result in air escaping through the 10mm set screw hole which leads to a false impression that the pressure cap seal is failing. You must carefully remove the o-rings without scratching the Hyperbloc100 (use a plastic or brass pick) and then use a borescope if you have one to ensure there is no debris inside of the o-ring grooves.