Pulsation Dampers that do; flow goes through but pressure pulsation does not. PulseGuard Ltd. designs and manufactures in-line, flow through pulsation dampers, hydro pneumatic accumulators, single connection accumulators for flow fluctuations, surge arrestors, and other related pressure vessels / fluid flow control equipment. Some specialties include bladderless dampers, thermal expansion and contraction (volumetric) compensators, surge alleviators, shock alleviators, piston type hydraulic accumulators, indicating accumulators, bladder type accumulators, water hammer arrestors, as well as other pressure control and safety equipment. Computer aided vibration and pulsation analysis or diagnostics (measurement and diagnostics of piping systems by pressure, amplitude and frequency) and computer modeling for pump start up surge, rundown vacuum impulsion, and valve closure time based water hammer or shock analysis are also available. Pulseguard Ltd. Guarding Against Pressure Pulsation ( http://www.pulseguard.co.uk/ ) Shockguard Ltd. Guarding Against Shock, Surge and Water Hammer ( http://www.shockguard.co.uk/ ) HydroTrole Ltd. Offshore Oil and Gas Hydro Pneumatic Accumulators ( http://www.hydrotrole.co.uk/ ) Liquid Dynamics Pulsation Analysis, Diagnostics, and Prediction by Software ( http://www.ldi.co.uk/ )