to API Publication 2517 identifies the Guide Pole/Stillwell of a
floating roof tank to be a major source of evaporation loss and
the Guide Pole Cover is a relatively inexpensive device which Motherwell
Nayler Petroseals have developed to reduce these losses.
the Guide Pole Cover prevents wind blowing through the slots/holes
in the tank Guide Pole, eliminating the venturi effect and dramatically
reducing vapour emissions to the atmosphere.