In the map below, the blue pins represent non-Roberts Oxygen places (other gas companies, fire services providers, a homebrew shop, and a paintball shop), while the pink/purple pins represent the plentiful Roberts Oxygen places. Not all Roberts Oxygen locations were contacted, but there appears to be a range of prices ($17-22 for a 5# fill), with different policies for out of test tanks. Call your local one for details if interested.
NOTE: Gas providers all seem to be open M-F, business hours only.
Refill vs. Exchange
One way in which the locations differ is whether they will refill the same tank you bring in, or want to exchange your empty bottle for a full, ready to go tank. Some places will refill while you wait, but others may be busy and require you to return in a few days to pick it up. So generally the exchange process is more streamlined, but if you have a nice shiny tank you might not want to swap it for one with a bit more mileage on it. The information in the map above tries to highlight the policy of the individual location. One (almost?) universal rule is that the tank you bring into an establishment for refill or exchange must be “in test”. The next section describes the hydrostatic testing done on tanks for safety, and how to figure out when the test certification on a particular tank expires.
DoT regulations and Compressed Gas Assocation standards state that all tanks which are: 1) made of steel or aluminum, 2) used for the storage of CO2, and 3) which measure over 2″ in diameter must be hydrostatically tested every five years.
Hydrostatic testing consists of inserting the tank into a water-filled containment vessel and increasing the pressure to five-thirds (5/3) of its rated pressure. If the tank fails, as in the picture to the right, it does so in the water-filled container designed to confine and contain the blast. To determine the next test expiration date, look for the manufacturing date or the last test date on your tank. The date information is contained in a set of information stamped into the metal up near the valve of the tank. Here is an example:
DOT-3AL 1800 X16022 LUXFER 02A06 – 5# C02 TW7.6
- DOT-3AL = DOT class 3, Aluminum
- 1800 = 1800 psi rated pressure
- X16022 = lot number
- LUXFER = mfg name
- 02A06 = mgf date (Feb 2006)
- 5#CO2 = 5 lb max fill weight of CO2
- TW7.6 = 7.6 lb empty tank weight
The above tank would be due for a new hydrostatic test in February 2011. When tested, the date of the new test is stamped into the tank. Prices for hydrostatic testing vary a bit, but generally ranged from $14-22 as of April 2010.