Every winter, vapor recovery units fail in the same few ways: condensate freezes where it collected, trace heating quietly stopped working in autumn, and someone started a stiff vacuum pump too hard. A pre-winter service pass plus a small set of habits keeps the unit running until spring.
Draining Before the Freeze
Condensate collects at separator bodies, collection pots and low-point drains, and every one of those becomes an ice plug below zero. Drain the system fully before first frost, then keep a daily drain habit through the cold months; a drain valve cracked slightly open with a catch container beats an ice block discovered by a pressure alarm. Transfer recovered liquid out of collection tanks on schedule rather than letting it sit through a cold snap.
Trace Heating and Insulation
Electric trace heating keeps vapor lines above freezing, but only when it works. Walk the runs and check for damage, verify connections are sealed against water, and confirm the controller settings suit the lines it protects. Wet insulation is worse than none: it freezes into a jacket that hides the problem while blocking the heat. Repair insulation before the weather that tests it.
Gentle Starts in Cold Oil
Vacuum pump oil thickens as it cools, and a cold start at full load runs high current through stiff clearances. Hand-turn the pump to confirm it moves freely, allow any pre-heat provision, then run unloaded for a few minutes before the unit takes on duty. Change oil before winter per running hours, using the cold-grade oil the pump manufacturer specifies, and record the change.
The Pre-Winter Service Pass
In late autumn, one planned session covers the season: drain, test trace heating, service the pump oil, exercise drain valves, verify gauge accuracy and run a start-stop cycle on the controls. File the record, and repeat the walk after the first real cold snap to catch what the first freeze revealed. Spring brings the mirror-image check when the thaw refills lines with meltwater.
| Task | When | Point |
|---|---|---|
| System drain | Before first frost, then daily | Every low point |
| Trace heating | Pre-winter and monthly | Damage, wet insulation |
| Pump oil | Pre-winter | Cold-grade, hours logged |
| Controls check | Pre-winter | Start-stop cycle verified |
Frequently Asked Questions
Is lower recovery in winter a fault?
Vapor generation drops with temperature, so recovered volume falls too; compare with the same month last year before diagnosing equipment.
How should a frozen line be thawed?
Isolate it and thaw slowly with heat tracing or warm water; never with an open flame anywhere near fuel vapor.
What about the collection tank over winter?
Keep it transferred down; a tank of liquid through a hard freeze risks ice expansion and a spring of repairs.
Does VOHON support winter operation of its units?
Yes. VOHON provides vapor recovery units with seasonal operation guidance; reach the team at lixiang@vohon.cn.