From Haestad Methods web site:

HAMMER from Haestad Methods demystifies the complex science of water hammer and transient analysis and puts the power to perform this critical work in your hands. With HAMMER, you can build your network from scratch using simple drag-and-drop layout tools. You can also interface seamlessly with EPANet, WaterCAD, WaterGEMS, and other hydraulic models to streamline the model-building process.

Model Any Transient Event
HAMMER allows you to quickly set up and model any transient initiator. Simulate pump trips or emergency shutdowns, pump restarts, sudden valve operations, rapid operation of wicket gates, turbine load shedding, rapid changes in demand, pipe bursts, and cyclic/periodic changes in head or flow.

Surge Protection Equipment
HAMMER contains the most comprehensive suite of surge control devices. The user can select from over 20 devices and perform an unlimited number of operating scenarios to develop the most appropriate strategy for surge mitigation.

Protective devices
Surge tank (open, spilling, one-way, orifice, bladder, variable area, differential)
Gas vessel (air chamber)
Check valve—mechanical or electrical control
Pressure-relief valve
Station-bypass line with check valve
Inline bypass with check valve
Air-inlet (vacuum breaker) valve
Air valve single, double, and triple acting
Air valve slow closing
Combined air valve
Hydraulically controlled slow-closing air valve
Surge-anticipator valve
Rupture disk

Control Strategies
Increased pump/turbine inertia
Realignment of pipe route and profile
Pump/turbine operating schedules
Valve operation strategy

Surge Hydraulic Elements
HAMMER contains all the commonly used hydraulic elements found in pipeline systems. And for the uncommon ones the user can easily develop a user-defined element.

Reservoir
Pumps (4 quadrant)
Pump shut down after delay
Variable speed pump
Turbine
Pressure regulating valve
Flow sustaining valve
Pressure supplier
Sprinkler
Check valve
Gate valve
Globe valve
Butterfly valve
Needle Valve
Ball Valve
User Defined Valve
Air valve single, double, and triple acting
Air valve slow closing
Discharge to Atmosphere
Dead end
Constant Flow Draw-Off
Periodic Head/Flow

For more information see HAMMER web page.