distinguishing between fire bricks

[nefiwashere]

is there any way to tell the difference between low medium and high duty fire bricks?

thinking about buying some bricks from a local guy that has a bunch but he does not know what type he has. selling them at .90 a brick, only place in town sells them for 2.50 a brick

thanks for any help

[RTflorida]

Re: distinguishing between fire bricks

weight is one way. Typically, insulating (white) fire bricks are about 1.5 - 2 lbs
Lite duty in the 5 1/2 - 7 lb range, Medium around 8-8 1/2, Heavy duty are usually over 9 lbs. The weights can vary by several ounces per brick. My light duty had a rather odd size 2.25 x 4 .25 x 8 .75. all 215 varried by abount 1/8"in one or all measurements. My brick would naturally weigh less than a true 2.5 x 4.5 x 9.
If memory serves me, mine ranged from 6 lb 4 oz to about 6 lb 8 oz

RT

[nefiwashere]

Re: distinguishing between fire bricks

thanks, i figured that would be my best bet