can make. Calibration gas cylinders are always identified with an expiration date. Your expiration date may pass before your cylinder is completely used. Always have a procedure in place to ensure you check and replace your Dry Gas before it expires and you are leſt without a calibration gas. Checking the date just as you confirm the standard every time you use the cylinder is a best practice.
I found a good deal on 34-Liter calibration gas on EBay. Should I buy it?
Most likely not. All calibration gas manu-
facturers atach an expiration date to their cylinders. Your eBay Dry Gas cylinder may have never been used but it may also be expired or well along the path to expiration. Always check expiration dates when using and receiving a calibration gas cylinder. Always get your calibration gas from a reputable supplier who you know to have Hazmat certified shipping personnel.
Can I carry Dry Gas onto a plane or transport it with checked luggage?
No. Dry Gas falls under Hazmat rules
and regulations which require any employee who is physically responsible for packaging and shipping Dry Gas to be Hazmat certi- fied. Companies are not Hazmat certified,
Figure 3: A Dry Gas cylinder recycling tool. Safely and easily remove the cylinder valve stem and open the cylinder contents to the atmosphere allowing the empty cylinder to be recycled.
individuals are. Hazmat rules and regula- tions are another good reason to purchase your Dry Gas from a reputable supplier who complies with Hazmat regulations (for more information on Hazmat regulations see htp://
www.phmsa.dot.gov/hazmat/regs).
Is it Damaging or Dangerous if a Dry Gas cylinder is left in the car overnight during the summer or winter?
Dry Gas is safe to handle and use with
proper care. Te DOT does not provide for Calibration Technician review and study of Te Material Safety Data Sheet (MSDS) for Dry Gas. Te MSDS covers a broad range of important safety information and procedures including “Hazard Identifica- tion”, “Handling and Use” and “First-Aid Measures.” Te MSDS should be included with every canister of gas received. A best practice is to retain MSDS sheets in all locations where Dry Gas is used including in instrument travel cases. Anyone in your business who is responsible for Dry Gas handling and use, should ensure they have have reviewed the MSDS. Dry Gas cylinders are pressurized and should always be handled with respect. Use safety glasses when handling cylinders under pressure. Always let your Dry Gas adjust to room temperature before use and use in a well-ventilated area. Extreme cold or hot will modify the alcohol level in the vapor exiting a Dry Gas cylinder. For this reason, cylinders should be allowed to come to room temperature prior to use. In extreme cold situations it is possible for
ethanol in a Dry Gas cylinder to condense inside the tank. While not dangerous this could cause lower than expected BAC readings on the instrument. High heat will raise the pressure inside the cylinder causing the tank to automatically vent gas. A rule of thumb is that you can expect a 1 psi increase per 10°F in temperature increase. So a stan- dard 500 psi 34L Dry Gas tank leſt in a car at 130°F will experience about a 6 psi increase
22 datia focus
in pressure. In order to prevent extreme pressure build-up, Dry Gas cylinders are manufactured to automatically vent gas at pressures well below that needed to raise cylinder pressure to dangerous levels. Te risk of storing Dry Gas cylinders in
a hot car is not that the tank will burst, it is that the cylinder will have a shorter life as it is likely to automatically vent gas at elevated temperatures. Most cylinder labels will state the following: “Do not use or store near heat or open flame. Exposure to temperatures above 125 o F (51.6 o C) may cause contents to vent or cause bursting.”
What exactly does NIST traceable mean and is it important?
Te National Institute of Standards
(NIST) is a U.S. government organization that is the official keeper of calibration. Tey hold the highest level of measurement accuracy in the United States. “Traceabil- ity” can be defined as an unbroken record of documentation or an unbroken chain of measurement from the user through the supply chain back to NIST. Te elements comprising NIST traceability are: 1. An unbroken chain. Te instrument’s calibrated indications must be able to be traced along an unbroken chain to NIST.
2. Measurement uncertainty. Te measure- ment uncertainty for each step in the traceability chain must be calculated or estimated. Terefore, the overall uncertainty for the whole chain can be calculated or estimated.
3. Documentation. Each link in the chain must be performed according to previ- ously documented and agreed upon procedures.
4. Te intervals of calibration. Calibrations must occur at regularly repeated intervals. Traceability is implemented via date and
lot codes on your gas cylinder. Tis trace- ability has proven its worth in past recall situations where each level of the supply chain can help its customers identify and
spring 2013
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