Expansion Tank Type There are two basic expansion tank types: Plain steel and bladder-type. Both are intended to control the high end pressure of your boiler system and keep the relief valve from opening due to increased system pressure caused by the expansion of water. Plain steel tanks have no moving parts, and require a separate pressure reducing valve to maintain initial fill pressure of 12 psi (or higher depending upon the requirements of your system). This type of tank looses its air cushion over the years and will need to be drained periodically. Bladder-type tanks contain a moving bladder, and requires either a separate pressure reducing valve (as mentioned above) or a fill-trol valve to maintain initial fill pressure of 12 psi (or higher depending upon the requirements of your system). This tank will not lose its air cushion unless the bladder becomes detached, at which point the tank would need to be replaced.	Bladder

Max Temp	200 °F

Tank Volume	4.4 Gallons

Max Accept Volume	2.42 gallons

Max Water Pressure	150 PSI

Weight	4 lbs

Depth	11 Inches

Height	15 Inches