Bladder Surge Tank – The pre-set pressure (Ps) is the initial pressure in the bladder prior to opening the valve connecting the tank to the pipeline. At any pipe pressure lower than the Pre-set pressure the bladder fills the tank and there is no flow into or out of the pipeline. This is an undesirable condition. The initial gas volume (Vi) is determined by InfoSurge using the initial line pressure (Pi) at the location of the bladder tank. This gas volume is calculated assuming isothermal compression (PiVi = PsVb). For example, for the data displayed above if the initial line pressure at the 50 cubic foot Bladder Tank is 80 psi, the initial gas volume is Vi = (Pa + Ps) x 50/(80 + Pa) = 13 cubic feet. Here, Pa is atmospheric pressure (14.7 psi).

Disable This Surge Protection Device

If this box is checked, then the selected SPD will not be modeled in the Surge analysis.

Device Type

Type of Surge Protection Device to be used.

Bladder Surge Tank Input Data

  • Inflow Resistance - This specifies the amount of resistance to flow into the system (pipe).

  • Outflow Resistance - This specifies the amount of resistance to flow out of the system (pipe).

  • Diameter - This is the diameter of the surge tank.

  • Preset Pressure - This is the value that the pressure in the connecting pipe must exceed in order for this device to operate. Pressure units are determined by the units selected in the Simulation Options. 

  • Initial Level - The initial level of water in the surge tank. The default is zero.

  • Tank Volume - This is the volume (m3 in SI/ ft3 in English) of the bladder for the tank.

  • Expansion Constant - This is the expansion constant for the gas that is used to fill the bladder. This value should be between 1 and 1.4. A value of 1 is used for isothermal compression (no temperature change) and 1.4 is used for adiabatic (temperature change present). In general, if you do not know this value, use 1.2. This data can be obtained from the tank manufacturer.

  • Variable Area Tank - When the option is checked off, the surge tank is cylindrical; otherwise, the surge tank has a variable area cross section and a Variable Area Tank Curve is required. Note that Diameter is not required for the Variable Area Tank.

  • Variable Area Tank Curve - Enter the ID of a curve that represents the Variable Area Tank.

Purge - Use the Purge button to remove existing Data.

Create/Update - Enter new or changed data and exit the dialog box.

Cancel - Cancels any new or changed data and closes the dialog box.