The TW10.3 is the tare weight, the weight of the tank empty, 10.3 lbs. My
guess is that the 7X56 is the original hydro date (July, 1956) based on its
position under the other numbers, and the 10M80 is from a retest in October,
1975.

-----
Regards,
Carl Ijames
"Danny D." wrote in message ...

Which of the myriad numbers on my tank is the hydro date?

I have this 5 pound carbon dioxide tank for making soda:
https://c4.staticflickr.com/4/3913/1...032661cb_b.jpg

I bought the original from Praxair, who replaced my brand new C02
tank with a cruddy one, and then swapped it out continually:
https://c4.staticflickr.com/4/3930/1...93defdba_b.jpg

I've been swapping out the tank for years, but lately, they don't
have the 5-pound C02 tanks size in stock. They say their supplier
doesn't have the "steel" (which is their nickname for empty tanks
to fill).

This lack of "steel" has been going on for weeks.

So, today, I called up the other two local suppliers:
1. Praxair 408-588-2035 $29.49 for a swap of steel for steel
2. Airgas 408-998-63.90 $33 for a swap of steel for steel
3. Carbonic 408-727-8835 $20 for a refill of steel

For the first two, I can swap out the Praxair tank and they will
take it, even if it is past its 5-year hydro test point (which
is how Praxair talked me into swapping out my brand new tank
for their beat up ones all the time in the first place).

But, Carbonic (naturally) won't fill it if it's past its
five year hydro date.

Question is:
hhhhhhhhhhh

TW10.3V
https://c4.staticflickr.com/4/3887/1...0f19b386_b.jpg

10M80
https://c3.staticflickr.com/3/2943/1...264ae186_b.jpg

7X56
https://c4.staticflickr.com/4/3837/1...b078f911_b.jpg