What is in a Vapour Recovery Unit (VRU) Package?

Beyond the core components, a vapour recovery unit package is only as reliable as the integration of those components. Piping design, elevation data, and liquid handling theories all influence long-term performance. Poorly sloped piping or insufficient drain points can allow liquids to accumulate upstream of the compressor, increasing the risk of slugging and mechanical damage. For that reason, VRU packages are often designed with deliberate piping geometry and dedicated liquid-return paths to safely manage condensate. 

Control systems are another critical but often underestimated part of a VRU package. Effective VRUs rely on stable inlet pressure control to prevent tank overpressure while avoiding excessive suction that can pull liquids into the system. This typically involves pressure control valves, variable speed drives, or automated bypass strategies that respond smoothly to changing vapour generation rates. Inconsistent control logic is a common cause of cycling and nuisance shutdowns in the field. 

Discharge conditions also deserve attention. Depending on destination pressure and gas composition, discharge cooling and temperature monitoring may be required to protect downstream piping and ensure the recovered vapour remains within acceptable operating limits. Overheating at discharge can shorten compressor life and limit the routing of recovered vapour. 

Taken together, these details explain why VRU performance is driven less by compressor size and more by package design. A well-engineered VRU treats vapour variability, liquids, and controls as design inputs rather than afterthoughts, resulting in a system that remains stable across seasons and operating conditions. 

What Are the Main Components of a Vapour Recovery Unit? 

Most VRU packages include an inlet separator or suction scrubber, a compressor, discharge cooling (if required), controls and protection instrumentation, and the piping and valving needed to integrate the package safely. 

Why Do VRU Inlet Conditions Matter So Much? 

Tank vapours can be saturated, and conditions can change quickly. If inlet pressure control is unstable or restrictions are too high, you can see tank pressure swings, compressor surging, increased carryover risk, and nuisance shutdowns. When the inlet is designed properly, the VRU becomes almost invisible to operations; it simply does its work.

Eagle’s vapour recovery systems are designed with operational features such as low-pressure inlet control, reduced inlet restriction, and enhanced liquid control, specifically to improve stability in heavy oil tank vapour recovery applications. 

How Do VRUs Support Environmental Compliance? 

Capturing vapours reduces venting and helps meet emissions requirements and internal ESG targets. In practical terms, a VRU helps you convert “lost gas” into a managed stream that can be used, sold or routed to a controlled system. The exact requirements vary by jurisdiction and facility, but the engineering purpose is consistent: keep vapours out of the atmosphere while maintaining safe tank pressures. 

If you are planning a VRU project or troubleshooting one that is not meeting expectations, start with our Vapour Recovery solutions and reach out to Eagle Pump & Compressor for a design review.