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6.4.11 Static
Static can be generated in any circulating fluid system. This is not a fault with the equipment, but an
unfortunate and accepted occasional side effect of the methodology. The following is provided for your
information only and is not intended to be a definitive guide as to what action to take in the case of
static build up.
Possible causes of static
Generally, oil-based thermofluids (heat-transfer fluids) are not good conductors of electricity and can
therefore produce static charge. This is because, whilst in use, they are creating constant friction with
the tubing, reaction vessel jacket and the inside of the thermoregulator. This is similar to what happens
when rubbing a balloon on a nylon jumper to make it stick to a wall. Some thermofluids are better than
others, and not all will create static.
In some cases, the friction generated from the stirrer shaft turning in the reactor contents can also
cause static, though this clearly depends on the makeup of the contents. It is also possible that site and
environmental factors can have an effect on static. However, there are numerous reaction systems in
the field that are pumping oil around a reactor, and only a small percentage have static issues.
Possible solutions
There are two popular methods for reducing or eliminating the risk of static build up in a system, and in
most cases it would be prudent to adopt both:
1 The use of earthing lines to connect all of the system components (reactor, framework,
thermoregulator, etc.) to an earth line. This is often the accepted practice in process and plant
installations.
2 Adding an anti-static additive/oil to the thermofluid, which helps make the thermofluid a better
electrical conductor. It is important to ensure that the additive is compatible with the
thermofluid in use and that its concentration is maintained (even after thermofluid changes).
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