The equipment on each truck is certified (thermometers, hydrometers and gauges). Certifications on the gauges and thermometers are renewed each year. Hydrometers are replaced and certified, when needed. Copies of each certification are available on each truck, as well as in a PDF file that can be provided at the customer’s request. As certifications are updated/changed, copies are replaced both on the truck and PDF.
The proving truck itself also has a water draw certificate and is valid for three years. (Except for Unit 1101, which is re-certified every two years to satisfy requirements to operate in Arkansas and Tennessee.) Again, copies are available on each truck and here in PDF.