Gas Handling

Updated by Janet 9/17/2014

Summary

We use many compressed gas cylinders in our labs: KrF/Ne premix for the excimer laser, high purity He to purge the excimer laser and to refill the CCR compressor, regular grade He for leak detections, N2 to vent the vacuum chambers, high purity O2 as a deposition gas, Ar or Ar/O2 mix as a sputter or PLD gas, and high pressure nitrogen to run the MMR cryostat. And others! You should understand the safety issues associated with the gases themselves (toxicity, reactivity) and with the fact that they are at high pressure. Understand how to identify and use regulators, gas lines. Know where to order them.

Supply and Ordering

A gas cylinder should ALWAYS carry an accurate label that specifies FULL, IN USE (with pressure and date if possible) or EMPTY. This saves an enormous amount of time. Use masking tape to label if you can't find the official label, and remove old labels.

All gas cylinder MUST be secured with a strap to a bench or a wall at all times. Do not strap more than about 5 cylinders together. This is extremely important. Gas cylinders are basically torpedoes. NEVER let them drop. Strap cylinders to the gas cart to wheel them around.

Gas cylinders obtained from vendors are subject to monthly rental, so send them back promptly to the vendor who supplied them. Usually the vendor name is stamped on the cylinder neck. A few gas cylinders belong to us (no stamp on the neck and supposedly labeled as ours) and we do not pay rental on them, and we can get them refilled by Industrial Welding Supply. As of 2014, we have one standard compressed N2, one standard compressed He and one standard compressed O2 cylinder.

Most gases come from Industrial Welding Supply, 880 NE Circle Blvd, Corvallis, OR 97330; (541) 752-8686 - Christine. (Christine is in Albany office. Salem office is HQ)

Call the Corvallis office to order or to schedule pickup. IWS delivers to OSU on Tuesdays. The delivery person comes to the lab BUT MUST BE LET IN because he/she MUST secure the new cylinders and the pickup cylinders must also be secured. Someone must sign for the cylinders upon delivery. (IWS cylinders are stamped with the IWS name, but because IWS was at one time the distributor for BOC specialty gases, sometimes BOC sylinders come from IWS.)

We also buy the KrF premix for the PLD laser from Airgas in Corvallis (since 2014). Previously from Linde (formerly Spectra gas). Airgas also has other specialty gases, e.g. high pressure (10,000 psi) N2 cylinders for the MMR cryostat, 5N He for the closed-cycle fridge compressor and the PLD laser. Call the company to schedule order and pickup.

Airgas contact person is Scott Cannoy (Scott.Cannoy@airgas.com). He will dispatch someone to collect. Airgas has cheaper high-purity gases.

We can obtain some gases from the OSU Chemistry Department (helium, oxygen).

Other vendors: PRAXAIR (Eugene and Salem); BOC specialty gases

Useful Info

Connecting gas bottles

Here is a good resource about how to connect gas bottles and the safety issues associated with cylinders. (JT - this was a great site, but now it's gone and I have yet to find an equivalent …) It also has information about different types of connectors: all gas bottles and regulators have standardized fittings that are particular to particular gases. Regulator fittings are labeled by CGA-number (CGA = Compressed Gas Association). CGA-580 is used for inert gases (Argon, Nitrogen, Helium etc.). Oxygen fittings are different and labelled as CGA-540 (puts a high barrier to your accidentally venting highly reactive gas). A list of CGA fittings can be found at this CONCOA site. Ted Pella also has information about standard fitting types in non-US labs.

YouTube video (5:31) on safety basics and how to move a cylinder and attach a regulator. Good for beginners.

YouTube video (1:46) on moving cylinders and how to move a cylinder and attaching a regulator. Good for beginners.

YouTube video (1:56) on how to operate a pressure regulator - very good for everyone!

YouTube video (9:10) about the markings on gas cylinders. How to identify contents, serial number, who owns it, maximum pressure, testing etc. Very useful.

This Beswick website has a description of how a pressure regulation valve works. The Matheson page has more detail and lots of information about different types of pressure regulators.

Most of our gas cylinders operate at about 2000 - 3000 psi on the high pressure side (regulator gauges are usually 2000 psi max or 4000 psi max) and are then regulated to a few psi or so on the low pressure side (regulator gauges usually 400 psi max). We had one cylinder that that operate at higher pressure (10,000 psi) and it requires a special regulator (very expensive, but I can't find it in the lab .. we need to look). Always check the regulator to make sure it matches the pressure marked on the bottle.

Watch the video about how to connect regulators. You need an adjustable wrench (12“ at least) and don't over-tighten. You should not need teflon tape on a cylinder connection, but teflon tape can be useful when connecting a gas gauge to a regulator body.