The Neon Bender's BBS!

The Archive no longer allows posting but search of hundreds of previous posts are available
If you have any questions please contact us.

[Please Read]

[ View Thread ] [ Return to Search ] [ Read Prev Msg ] [ Read Next Msg ]

Re: FLASHBACKS! not the groovy 60's!

Posted By: John Anderson
Date: Thursday, 30 October 2008, at 11:45 p.m.

In Response To: FLASHBACKS! not the groovy 60's! (Darryl Thompson)


I realize there are differing views on metal vs. non-metal, grounding vs. ungrounded, etc. Here is my view:

Every neon pumping system has conductive material in it at some point. To my knowledge, no-one has made an all-glass, non-conductive mechanical pump, or even a belt that doesn't become conductive once it absorbs crud and oil. If your pump plugs into the AC outlet, it's got substantial potential to ground, even if you leave off that "green" wire, and mount the belt-driven pump on insulators. Neutrals (white) almost always go back to the electrical panel ground in residential systems. In short, you cannot build a completely isolated system. If you have a direct drive pump, then you basically have a system ground - and you as the manifold operator are right in the middle where a flashback must pass through. Maybe you'll be lucky and remain isolated enough to avoid a discharge - but in my opinion you're taking a risk.

Most neon manifolds are a hybrid of conductive and non-conductive materials. Glass manifolds, metal vacuum gauge heads, Robbin's metal filling valves, cylinders, turbo pumps, etc. At some point EVERY neon pumping system has conductive material a flashback can seek. If your bombarder is running off AC power from the line, you can't eliminate all potential to ground... even with a completely floating secondary. True, an HV discharge may bounce around to many points. But it's looking for a place to discharge its mother load. Take steps to ensure it's not you. As a human body contains mostly salty water, you can inadvertently become this path yourself unless you're suspended in air off the floor. And even then, there is substantial capacitive coupling to ground I would never take a chance on.

Yes, an ungrounded metal manifold would be VERY dangerous. So would ungrounded metal filling valves. Should the bomber button accidentally engage, you could be toast! No conductive parts a human is likely to touch during bombarding should be ungrounded. Further, a well-grounded electrode placed between the manifold and the tube being pumped provides a path to ground should a flashback occur. Does it encourage flashbacks? That's not been my experience, except on pole-pigs wired as mid-point grounded units (a poor choice for neon use). Unless you can isolate every conductive object (including yourself) from potential to ground, you cannot guarantee YOU won't be the ground-return. Everyone makes mistakes - a simple mishap of touching a conductive part of your manifold while bombing shouldn't put you in a life-threatening position.

Many neon pumping systems around the worlds operate safely with conductive metal components - even with all-metal valves (just to be clear, I'm a big fan of glass manifolds). At some point (of course) you have to make the transition to glass. Where this occurs should dictate your plan for safety grounding. Semiconductor manufacturers safely use high-current, high-frequency, high-voltage discharges all the time with metal systems during processes like vacuum deposition, and many others. How? They ground the metal systems well, and provide a conductive path before it passes by components humans touch.


Messages In This Thread

[ View Thread ] [ Return to Search ] [ Read Prev Msg ] [ Read Next Msg ]

Neon Bender's BBS! is maintained by Kenny with WebBBS 5.12.

This page Copyright © 1996-2005 Krypton Neon