You must be registered with TDA before you can receive payment of any kind for:
    - placing a device into service, 
    - removing an out-of-order tag or 
    - performing inspections of LPG meters or ranch scales.

TDA may issue a registration to each person who submits an application and passes a written examination for each class of license desired.
Registrations are valid for five years.

Exams

        Convenience Testing for Service Technicians
        Licensing and Examination Process

Classes  
  

	Class 1:	Scales 0 to 300 pounds capacity
	Class 2:	Scales 301 to 3000 pounds capacity
	Class 3:	Scales 3001 to 40,000 pounds capacity
	Class 4:	Scales more than 40,000 pounds capacity
	Class 7:	LPG measuring devices

NIST Handbook 44

Download the current version of Handbook 44