(a)  Secondary Standards. - Each utility shall own or have access to a dead weight tester. This instrument must be maintained in an accurate condition.

(b)  Working Standards. - Each utility must have water manometers, mercury manometers, laboratory quality indicating pressure gauges and field type dead weight pressure gauges as necessary for the proper testing of the indicating and recording pressure gauges used in determining the pressure on the utility's system.

(c)  Periodic Checks. - Working standards must be checked periodically (see Rule R6‑25(5)) by comparison with a secondary standard.

(d)  Handling of Standards. - Extreme care must be exercised in the handling of standards to assure that their accuracy is not disturbed.

(e)  Certificates or Calibration Cards. - Each standard shall be accompanied at all times by a certificate or calibration card, duly signed, and dated, on which are recorded the corrections required to compensate for errors found at the customary test points at the time of the last previous test.