175. Section 174 does not apply to an operator of a metallic surface treatment process that reduces surface tension of a solution containing hexavalent chromium so that the tension does not exceed
(1) 35 dynes per centimetre when the tension is measured with a tensiometer;
(2) 45 dynes per centimetre when the tension is measured with a stalagmometer.
The operator must measure that tension once a day for each vat used, and take 2 successive measurements at least 16 hours apart.