Supported Elements and Devices for Surge

Pipe2016: Surge node elements include open surge tanks, closed surge tanks, hybrid tanks with compressors, hybrid tanks with dipping tubes, one-way open tanks, bladder surge tanks, 1, 2, or 3-stage air vacuum valves, pressure relief valves, surge anticipation valves, and rupture disks.  Surge also supports most of the steady-state devices available within KYPipe.

 Surge Device Inputs and Graphical Description

Surge Device Text Description

Check Valve – Inserted into a pipe, this device allows flow only in the specified direction. If conditions exist for flow reversal, the valve closes and the line carries no flow. Active valves and pumps may also incorporate check valves. Note: the directional arrow should be in the normal direction of flow.

Pump – Pumps are connected to one or more pipes. Surge pumps may be defined by head-flow data or a pump file.

Single-Stage Air Vacuum Valve – This device takes in air when the pipeline pressure drops below atmospheric and releases air when the pipeline pressure exceeds atmospheric. The single-stage air valve has the same sized orifices for inflow and outflow (usually the same orifice). Also an initial volume of air can be specified to model startup.

Two-Stage Air Vacuum Valve – This valve has different-sized orifices for inflow and outflow. The outflow orifice is smaller to reduce the rate of air expulsion and the “air slam” which occurs when all the air is expelled and the liquid columns rejoin. See single-stage air vacuum valves.

Three-Stage Air Vacuum Valve – This valve has a second outflow orifice (smaller) to release the air more slowly and reduce “air slam.” The transition from the primary outflow orifice (diameter D1) to the second orifice (diameter D2) usually occurs at a specified pressure (psi or kpa) but can be modeled to switch based on flow (cfs or cms) or volume (ft^3 or m^3). See two-stage air vacuum valves.

Closed Surge Tank – This tank has a volume of gas, usually air, in the space above the liquid. The gas expands and compresses as flow leaves and enters the tank.

Bladder Surge Tank – This is a closed surge tank with a gas-filled bladder. This tank activates at the set pressure for the bladder, and acts as a closed surge tank for pressures above the set pressure. For pressures below the set pressure, the tank has no effect.

Dynamic Air Valve – After activation, dynamic air valves continue to allow water (not just air) to flow out after all air is vented. The valve is gradually closed to reduce water column velocity in a highly controlled manner eliminating air slam pressures.

Electronically Actuated Surge Anticipation Valve – This is a combination of a Surge Anticipation Valve and an Hydraulically Actuated Surge Anticipation Valve. It opens at a specified pressure at a sensing node.

Hydraulically Actuated Surge Anticipation Valve – This is a surge anticipating valve that is controlled by the pressure at a sensing node rather than time. It can model both low- and high-pressure pilots. The Low Pressure Pilot (LPP) opens the surge anticipation valve during a downsurge when pressure at the sensing node drops below its setting and keeps the valve open until the pressure rises above this setting. The High Pressure Pilot (HPP) opens the Surge Anticipation Valve during an upsurge when pressure at the sensing node rises above its setting and keeps the valve open until the pressure drops below this setting.

The hydraulically actuated surge anticipation valve can utilize the closure characteristics of standard valves (butterfly, gate, globe, etc.) or can employ user-defined valve closure characteristics.

Open Surge Tank – This tank connects to a pipeline and is open to the atmosphere. The user inputs the  maximum (Max) water level; if the water level exceeds the maximum, the tank is modeled as a spilling tank. See Variable-Area Open Surge Tank if the tank is not a vertical cylinder.

One-Way Open Surge Tanks (Feed Tank) – This open surge tank is equipped with a check valve at the entrance which prevents flow from entering the tank. This is useful for controlling downsurges at a point where the static head is large and a normal open surge tank would not be practical.

Variable-Area Open Surge Tanks – This open surge tank allows the user to specify a height/volume relationship.

Pressure Relief Valve – This valve opens at a designated pressure (psi or kpa) or head (ft or m) and closes at a second (lower) pressure or head. The user specifies the  opening and closing times.

Horizontal Cylinder – For closed surge tanks and bladder tanks. When specified in the surge tank data, the horizontal tank is automatically handled as a variable area tank accounting for the volume/depth relationship for this tank alignment.

Rupture Disk – This device opens quickly (ruptures) at a specified pressure (or head).

Side Discharge Orifice – This node represents a simple orifice in the pipeline where flow enters and/or exits. It may also represent a pair of orifices: an inflow resistance is defined for the orifice through which flow enters the pipeline and an outflow resistance for the orifice through which flow exits the pipeline (the two can be equal to represent a single orifice). An external head may also be defined.

Siphon Breaker – Uses the concept that a submerged discharge located at a lower elevation than the required discharge creates a siphon which lowers the total head required by a pump. A siphon breaker valve is placed at the top of the siphoning section of a pipe. This valve is open when the pump is not operating or is beginning to close, breaking the siphon. It allows air to discharge during pump start-up. When the pipeline is full, the valve closes and maintains the siphon.

Surge Anticipation Valve – This valve is normally located at a pump discharge which opens on a downsurge at a specified pressure (or head) to provide protection for a subsequent upsurge. Once activated this device works on a timed cycle. The valve opens fully (Open Time) and stays fully open for a designated period (Full Time) and then closes (Closing Time). A sensing node can be designated if the opening is to be activated by the pressure at a different location.

Zero Velocity Valve – Also known as a reflux valve, this prevents flow reversal on rising mains. The user specifies the opening/closing time; the valve begins closing upon flow reversal.