Selecting an independent consultant in a specialist field.

[Fishy]

I take most consultants' websites with a pinch of salt! 

Water mist systems are particularly problematic to validate technically, partly because of the lack of agreed testing/design standards.  Not so difficult if you're designing for a particular, well-defined protection needs, but much more difficult to support more general applications.  Established manufacturers tend to have done a lot of testing and built up a technical library of design guidance. 

You'd be best advised to find someone who knows the technology well - probably an ex-employee of one of the established manufacturers or the test/certification bodies (for suppression in the UK this really means Warrington/Exova or BRE).