SAMPLING UNDER RESTRICTED OR CLOSED CONDITIONS

International standards recommend that a number of samples are required to prepare a “representative”
sample suitable for the determination of quality. Current API standards recommend Flow Proportional Inline
sampling equipment as the preferred method for obtaining samples. However, such equipment is
not widely available at the majority of locations and most samples are drawn manually from vessels and
shore tanks.
As more environmental and safety regulations are introduced, the ability to draw samples through open
tank lids is being prevented, resulting in samples being drawn through vapour lock systems. This
requires specialised equipment which can restrict the types of sample that may be drawn and may not
allow samples to be drawn in accordance with current manual sampling standards.
Gauging and sampling under restricted or closed conditions is to be the subject of a new API/EI (IP)
standard, which should be published in 2008. Development of equipment is ongoing and some already
exists which can be effective but is subject to operational constraints.
The problems experienced by our members in working with this equipment are already impacting on
operations, particularly where the cargo is non-homogeneous, or is of variable quality and/or viscosity,
such as residual fuels. Some of the more commonly experienced problems are:
1. Significant additional time is required for sampling, particularly of ships’ tanks, to allow repeated
fitting, operation and removal of the equipment.
2. The diameter of most vapour lock systems dictates that samples can only be of a limited
volume, normally less than 400 ml.
3. The design of most sample containers is such that the level of the sample inside the container
cannot be determined. This limits the ability to draw “All Level” or “Running” samples in
accordance with the standards.
4. The design of the equipment often allows only zone or spot sampling. Additionally, most
systems are limited to one sample container which must be used repeatedly, leading to potential
contamination during the sampling process.
5. The cleanliness of the vapour lock system is usually unknown and it cannot be cleaned while in
use. This can result in contamination of the sample.
6. Though the majority of restricted or closed equipment originates from two manufacturers, the
absence of an international standard regarding the type of vapour lock fitting has resulted in
many different types and sizes in operation on vessels, sometimes preventing the use of the
inspection company’s own equipment. Where vessel equipment has to be used it may not be
clean or in a serviceable condition.