Vertical surge tank is an H2S service vessel designed to store liquid hydrocarbons after separation. The surge tank is used to measure liquid flow rates, as well as the combined shrinkage and meter factor. It can also be used as a second stage separator and hold a constant backpressure by using its automatic pressure control valve on the gas outlet.
 
The surge tank usually consists of a single or double compartment vessel and a level measuring system with sight glasses or magnetic levels. To prevent overpressure and overfilling, the surge tank is fitted with a pressure-relief valve and a high- and lowlevel alarm system.

Surge tanks are designed with a diverter, a vortex breaker, and stiffening rings capable of withstanding a vacuum in the vessel. They are fitted with sampling, pressure, and temperature ports. A bypass manifold is also included.

All surge tanks are shock-protected by a frame, and operate in the vertical position, even they are transported in a horizontal position.

Applications
Onshore and offshore exploration and development oil and gas well testing
Production wells

Features
Single or dual compartment
Dual-compartment surge tank provide a means to empty one tank compartment while filling another
Sight glasses or magnetic level indicators
High- and low-level alarm on each compartment
Automatic pressure-control valve normally open on gas outlets
Diverter, vortex breaker, and stiffening rings
Bypass manifold allows isolating surge tank from flow process
Fitted with sampling points and pressure and temperature ports
Protected against overpressure by relief valves
Shock-protected by a frame
Compliant with ASME VIII, Div. 1 and NACE MR0175