Retrofit vapor recovery projects are decided by what the survey finds, not what the brochure promises. Existing stations carry their history in their layouts, their tank schedules and their electrical panels, and every surprise the survey misses becomes a variation order later. Walking the site with the right checklist is the cheapest phase of the whole project.
Tank and Manway Conditions
Record tank counts, sizes and fill points, and inspect manway interiors while the chance exists: bung conditions, existing risers, anything that a recovery connection will have to work around. Photograph everything, because six months later the installation crew will ask questions these photos answer in seconds.
Vapor Path and Grade Survey
Map the existing vent piping: routes, diameters, materials, slopes and every low point. Grade that worked for venting may not work for a recovery line with condensate in it, and a sag nobody flagged becomes a liquid trap nobody wanted. Include the vent stack locations and termination heights in the survey record.
Electrical and Control Survey
Confirm panel capacity, spare breakers, conduit routes and the distance from the proposed unit location to power. Existing stations accumulate loads over decades, and the panel that was generous in the drawings may be full in the field. Note the communication path for any monitoring the design expects.
Space, Access and Traffic
Where would the unit actually sit, and can it be serviced there? Measure the candidate locations against delivery truck routes, car wash queues and the daily rhythm of the forecourt. A unit installed where the tanker parks is a unit that gets moved eventually, at a cost the survey would have avoided.
| Survey area | Missed item becomes |
|---|---|
| Tank and manway detail | Connection rework |
| Vent grade and low points | Liquid traps in service |
| Electrical capacity | Panel upgrade mid-project |
| Unit siting and access | Relocation costs |
Common Questions
Can the survey happen while the station operates?
Largely yes, with manway inspections scheduled in a delivery gap. Plan the disruptive items deliberately rather than discovering them.
How long should a retrofit survey take?
For a typical station, a thorough day with the right checklist. The return on that day appears as variation orders that never happen.
Does VOHON support retrofit surveys for Stage III vapor recovery?
Yes. VOHON assists retrofit projects with survey checklists and equipment guidance for existing stations, reachable at lixiang@vohon.cn.